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Navid Saleh

Research Vision

Sustainable Nano-Engineering for Water Treatment Lab focuses on design and development of novel and human-centered water treatment technologies. The primary goal is to enhance economically challenged communities' access to potable water via innovative nanomaterial-enabled treatment processes. By integrating state-of-the-art experimentation and modeling under...

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Latest News


July 20, 2017
SusNWaTr group has published a book chapter, titled: “Dimensional Variations in Nanohybrids: Property Alterations, Applications, and Considerations for Toxicological Implications”. [more..]


July 7, 2017
Dr. Jaime Plazas-Tuttle, who graduated with a Ph.D. degree from the SusNWaTr group on May 2017, will be joining as an Assistant Professor in the Civil and Environmental Engineering Department at Universidad de los Andes, Bogota, Colombia. [more..]


July 1, 2017
Dr. Dipesh Das, who graduated with a Ph.D. degree from the SusNWaTr group on May 2017, will be joining as a research scientist of the nano-fabrication group in Intel Corporation at Portland, OR. Dr. Das established a unique nano-synthesis setup. [more..]


June 30, 2017
SusNWaTr group has co-authored a journal article in BioTechniques, titled: “Overcoming qRT-PCR interference by select carbon nanotubes in assessments of gene expression”. This study develops a novel protocol to overcome interference in qRT-PCR. [more..]


May 23, 2017
Dr. A. R. M. Nabiul Afrooz, a graduate from SusNWaTr in May 2015, recently left his postdoctoral scholar position at Stanford University to join as a research scientist in Southern California Coastal Water Research Project, Coasta Mesa, CA. [more..]


May 21, 2017
Five graduate students have graduated from SusNWaTr group this Spring. Dr. Jaime Plazas-Tuttle and Dr. Dipesh Das have done novel research on nano-enabled disinfection technology development and on emerging nanohybrids, respectively. [more..]


March 24, 2017
Saleh group has co-authored a journal article in NanoImpact, titled: “Importance and challenges of environmental ligand binding and exchange: Introducing single molecule imaging as a model characterization technique”. [more..]

SusNWaTr group has published a book chapter, titled: “Dimensional Variations in Nanohybrids: Property Alterations, Applications, and Considerations for Toxicological Implications”. This chapter reviews size/shape/dimensionality variations of nanomaterials due to hybridization and discusses property alteration of these NHs, relevant to applications and nanotoxicology. Former graduate students Nirupam Aich and Jaime Plazas-Tuttle are co-authors in this chapter.

Abstract: Hybridization of nano-scale entities lead to higher dimensional ensemble materials with multifunctionality. Such hierarchical complex materials though are engineered with output properties in mind, these evolved nanostructures possess unique shapes and physico-chemical attributes. Nanotoxicological considerations hinge on physical size and shape factors; thus, dramatic alterations to shape and dimensionality of ensemble nanohybrids (NHs) necessitate careful evaluation of this ‘horizon’ material class. This chapter reviews size/shape/dimensionality variations of nanomaterials due to hybridization and discusses property alteration of these NHs, relevant to applications and nanotoxicology. The chapter also discusses nano-bio interactions of novel nanohybrids in relation to their size, shape, and dimensionality, and outlines future research needs and strategies.



Dr. Jaime Plazas-Tuttle, who graduated with a Ph.D. degree from the SusNWaTr group on May 2017, will be joining as an Assistant Professor in the Civil and Environmental Engineering Department at Universidad de los Andes, Bogota, Colombia. He has carried out breakthrough research to enable microwave radiation for microbial inactivation in water. We wish him success in his future career.



Dr. Dipesh Das, who graduated with a Ph.D. degree from the SusNWaTr group on May 2017, will be joining as a research scientist of the nano-fabrication group in Intel Corporation at Portland, OR. Dr. Das has been instrumental in establishing a unique nano-synthesis setup at the SusNWaTr group. We wish him success in his future career.



SusNWaTr group has co-authored a journal article in BioTechniques, titled: “Overcoming qRT-PCR interference by select carbon nanotubes in assessments of gene expression”. This study develops a novel protocol to overcome interference in qRT-PCR analysis for carbon nanotube induced gene expression.

Abstract: Nanomaterials of various types, including carbon nanotubes (CNTs), can interfere with standard quantitative real-time polymerase chain reaction (qRT-PCR) assays resulting in inaccurate gene expression. Although such observations have been noted, the precise step in the qRT-PCR pipeline where interference occurs has not been well described. Here we investigated where in the process surface-oxidized multi-walled carbon nanotubes (oxMWNTs) inhibited the expression of the housekeeping gene, GAPDH, and explored several strategies to minimize such inhibition. We determined that the interference occurred during the reverse transcription (RT) step and found that doubling reaction reagents or adding bovine serum albumin (BSA) successfully mitigated the inhibition. Finally, we show that assay interference was observed for CNTs that were surface-oxidized but pristine CNTs did not cause the same level of interference. These results highlight the importance of monitoring qRT-PCR assays for interference by CNTs that differ by surface chemistry, as these nanomaterials are commonly used in gene expression assessments at concentrations that we have shown to be inhibitory.



Dr. A. R. M. Nabiul Afrooz, who graduated with a Ph.D. degree from the SusNWaTr group on May 2015, recently left his postdoctoral scholar position at Stanford University to join as a research scientist in Southern California Coastal Water Research Project, Coasta Mesa, CA. Dr. Afrooz worked on fate and transport of rod-shaped nanomaterials during his tenure at UT Austin. We wish him success in his future career.



Five graduate students have graduated from SusNWaTr group this Spring. Dr. Jaime Plazas-Tuttle and Dr. Dipesh Das have done novel research on nano-enabled disinfection technology development and on emerging nanohybrids, respectively. Three students, Christine Ngan, Anna Merryman, and Allison Hornstra, have also graduated with M.S. degrees this Spring.



Saleh group has co-authored a journal article in NanoImpact, titled: “Importance and challenges of environmental ligand binding and exchange: Introducing single molecule imaging as a model characterization technique”, led by Markita Landry’s group at UC Berkeley. This is one of the first studies that presents single-molecule imaging as a novel tool to assess soft corona morphology on carbon nanotube surfaces.

Abstract: Highly surface active nano-scale materials, when released into the natural environment, tend to adsorb geo- and biomacromolecules and end up presenting a modified interface to biological species. Capped nanocrystals and polymer/surfactant modified nanomaterials also are known to undergo ligand exchange when exposed to natural systems. Thus, nano-bio interactions will primarily be governed by the adsorbed or exchanged natural macromolecules. To-date there has been no established technique determining the kinetics of ligand exchange or characterizing the bound geobiomacromolecular corona in an environmental setting. Single-molecule imaging utilizing near-infra red spectrometry, and single-molecule imaging of fluorophore-tagged polymeric ligands can enable detailed characterization of biopolymeric corona. This perspective aims to highlight the importance of ligand exchange, identify roles of surface ligands on nano-bio interaction, and present initial evidence of macromolecular characterization on nanotube surfaces using single-molecule techniques. This commentary also aims to outline the challenges facing nano-environmental health and safety community on assessing biological interaction with complex nano-scale heterostructures in a realistic environmental matrix.



Dr. Saleh has co-authored a journal article in Langmuir, titled: “Sulfate Mediated End-to-End Assembly of Gold Nanorods”, led by Peter Vikesland’s group at Virginia Tech. This is one of the first studies that shows end-to-end assembly of gold nanorods by merely adjusting the sulfate counterions. Dr. Saleh has had a significant contribution in conceptualization and analysis of this novel work.

Abstract: There is interest in the controlled aggregation of gold nanorods (GNRs) for the production of extended nanoassemblies. Prior studies have relied upon chemical modification of the GNR surface to achieve a desired final aggregate structure. Herein, we illustrate that control of electrolyte composition can facilitate end-to-end assembly of cetyltrimethylammonium bromide (CTAB) coated GNRs. By adjusting either the sulfate anion concentration or the exposure time it is possible to connect GNRs in chain-like assemblies. In contrast, end-to-end assembly was not observed in control experiments using monovalent chloride salts. We attribute the end-to-end assembly to the localized association of sulfate with exposed quaternary ammonium head groups of CTAB at the nanorod tip. To quantify the assembly kinetics, visible-near infrared extinction spectra were collected over a pre-determined time period and the colloidal behavior of the GNR suspensions was interpreted using plasmon band analysis. Transmission electron microscopy and atomic force microscopy results support the conclusions reached via plasmon band analysis and the colloidal behavior is consistent with Derjaguin-Landau-Verwey-Overbeek (DLVO) theory.



SusNWaTr group has co-authored a journal article in Environ Sci Technol, titled: “Influence of the gastrointestinal environment on the bioavailability of ethinyl estradiol sorbed to single-walled carbon nanotubes”, led by Sabo-Attwood group at University of Florida. This is one of the first studies that systematically evaluates bioavailability of an endocrine disrupting compound (ethinyl estradiol), facilitated by single-walled carbon nanotubes. Senior Ph.D. students Dipesh Das and Jaime Plazas-Tuttle are co-authors in this paper as well.

Abstract: Recent evidence suggests that if single-walled carbon nanotubes (SWCNTs) make their way into aquatic environments, they may reduce the toxicity of other waterborne contaminants due to their sorptive nature. However, few studies have examined whether contaminants remain adsorbed following ingestion by aquatic organisms. The objective of this study was to examine the bioavailability and bioactivity of ethinyl estradiol (EE2) sorbed onto SWCNTs in a fish gastrointestinal (GI) tract. Sorption experiments indicated that SWCNTs effectively adsorbed EE2, but, the chemical was still able to bind and activate soluble estrogen receptors (ER) in vitro. However, centrifugation to remove SWCNTs and adsorbed EE2 significantly reduced ER activity compared to EE2 alone. Additionally, the presence of SWCNTs did not reduce the EE2 driven induction of vitellogenin 1 in vivo compared to organisms exposed to EE2 alone. These results suggest that while SWCNTs adsorb EE2 from aqueous solutions, under biological conditions EE2 can desorb and retain bioactivity. Additional results indicate that interactions with gastrointestinal proteins may decrease estrogen adsorption to SWCNTs by 5%. The current study presents valuable data to elucidate how SWCNTs interact with chemicals that are already present in our aquatic environments which is essential for determining their potential health risk.



Erica Mason, a ChemE sophomore working in SusNWaTr group has received Fall 2016 Undergraduate Research Fellowship. Erica has been working on an exciting water treatment project with functional nanohybrids. Congratulations Erica!



SusNWaTr group has published a journal article in ES:Nano, titled: "An Elegant Method for Large Scale Synthesis of Metal Oxide-Carbon Nanotube Nanohybrids for Nano-environmental Application and Implication Studies". This study presents a facile method for synthesis of carbonaceous-metal oxide nanohybrids. Dipesh Das, a 4th year Ph.D. student is the lead author of this paper. Senior Ph.D. student Jaime Plazas-Tuttle, 2nd year Ph.D. student Indu V, Sabaraya, and an undergraduate student Sneha Jain are co-authors in this paper. Dr. Sabo-Attwood of University of Florida has also co-authored this article with Dr. Saleh; this is Dr. Saleh's career's 51st peer reviewed journal article.

Abstract: Nanohybrids (NHs) with synergistic and emergent properties are used as electrocatalysts, photocatalysts, and antimicrobial agents in numerous applications. Carbon nanotube (CNT)-metal oxide NHs are one of the most commercialized heterostructures because of their advantages as catalyst supports in the fuel cell industry. To-date, there has been little understanding of their environmental behavior, primarily due to the lack of a robust yet facile synthesis technique. This study presents an elegant synthesis method, which varies reagent composition and ratio to grow metal oxides of choice onto multiwalled carbon nanotube (MWNT) surfaces. This technique can synthesize heterostructures with elements ranging from transition (Ti and Zn) to lanthanide series (Er and Pr) metals. This modified sol-gel method can provide large material yield (100s of mg) with high degree of overall homogeneity between synthesized batches. Such a method for preparing complex NHs from component materials can be extremely useful to perform systematic environmental analyses.



Dr. Saleh will be publishing the first textbook on environmental implications of nanotechnology with John Wiley & Sons Inc. Professor Vicki Grassian, chief editor of ES:Nano is the co-author with Dr. Saleh in this book. The goal of this text is to build and enhance student knowledge on a wide range of topics: synthesis, crystal structure, chemical and electronic (band gap) properties, surface properties (surface tension, surface pressure, adsorption of surfactants/polymers, etc.), environmental or occupational health implications (aggregation, deposition, transformation, toxicity), exposure and risk. It will also include discussions on nanotoxicity and risk assessment. The book is expected to be published by 2019.



Craig Ayres have joined SusNWaTr group. Craig has earned a B.S. degree in Civil and Environmental Engineering from Ohio State University. Craig has also worked at AECOM as a water/wastewater engineer prior to joining as a graduate student at UT Austin. He brings in expertise in nanomaterial characterization, fate and transport research, and treatment plant design and operational knowhow. SusNWaTr group welcomes Craig and wishes him the best in his graduate education.



Dr. Saleh has been selected as one of the top 10 reviewers for Environmental Science: Nano. The top reviewers are selected by the editor for their significant contribution to the journal in 2016. In celebration of 'Peer Review Week', RSC will be publishing the names of the top 10 reviewers on their blog during the week of the 19th September, to recognize the reviewers.



SusNWaTr group has published a book chapter, titled: "Aggregation Kinetics and Fractal Dimension of Nanomaterials in Environmental Systems". This chapter discusses aggregation processes of nanomaterials in the environment. Former graduate students A. R.M. Nabiul Afrooz and Nirupam Aich and current senior graduate student Jaime Plazas-Tuttle are co-authors in this chapter. The book will be formally published by John Wiley and Sons, Inc. by October of 2016.

Abstract: Understanding aggregation behavior of engineered nanomaterials (ENM) is key to predict their fate in aquatic environment and evaluate their interaction with biological entities. Although Derjaguin-Landau-Verwey-Overbeak (DLVO) colloidal theory provides the basic framework of nanoparticle aggregation process, unique surface properties of ENMs, i.e., functionality, surface heterogeneity, size, shape, atomic structure, etc. and extrinsic environmental conditions, i.e., pH, ionic strength, natural organic matter (NOM), and other particulate entities, complicate the mechanistic understanding of their aggregation kinetics. Moreover, non-DLVO type interactions, i.e., hydrophobic, magnetic, and interaction from emergent ENM properties present further challenges in evaluation of their aggregation behavior. Uncertainty in ENM aggregation not only makes their fate and transport determination difficult but also convolutes mechanistic understanding of nanotoxicity. This chapter discusses theoretical development and experimental techniques of ENM aggregation, reviews state-of-the-art aggregation literature, identifies key challenges, and proposes potential future research strategies to address these complexities.apeutics.



Jaime Plazas-Tuttle, a final year PhD student in the SusNWaTr group, has been awarded the "Kolodzey Travel Grant" from the CAEE department at UT. He will be presenting her research in the upcoming American Chemical Society National Meeting and Exposition, Philadelphia, PA. Jaime's presentation title is "The Power of Novel Metal Oxide-Carbon Nanotube Heterostructures: Enabling Microwave to Disinfect Water for Aquaculture".

Abstract: Over the past half a century, global food consumption has increased significantly, rising by nearly 400 kcal/person/day. Such growth has put tremendous stress on the food chain and access to high calorie diet should be at the forefront in ensuring global food security. Fishes (global aquaculture production of 50M metric tons of $100B per annum value) are effective protein sources for humans with the highest edible yield (~70% of the body mass utilized) and protein retention (31%) compared red meat (18%). Since water is the life-blood of aquaculture industry, ensuring suitable water quality is essential to the success of this industry. The Norwegian virus attack of 1984 as well as recent reports from FAO demonstrated the ability of pathogens to have severe consequences on aquaculture production. The current best practices in aquaculture involve ultraviolent (UV) disinfection to ensure biological quality of water. UV radiation is mutagenic to pathogens by breaking molecular bonds within micro-organismal DNA and producing thymine dimers. While this technique is largely successfully it suffers from three key limitations: (i) efficiency drops precipitously in turbid water; (ii) required irradiation time can be prolonged to inactivate certain pathogens, rendering this technology to be cost-prohibitive; and (iii) some pathogens are resistant to UV irradiation, e.g., viruses. Since chemical disinfection is not an option for aquaculture (due to the bioaccumulation risks of carcinogenic disinfection byproducts and other chemicals) development of a more effective irradiation-based technology is desired. This study presents a novel nano-enabled disinfection system, which utilizes low intensity energy waves, i.e., microwaves (MWs), to effectively disinfect water. Metal oxide-carbon nanotube heterostructures have shown to establish a synergy between adsorptive ability of microwave with the upconverting ability of the metal oxides to successfully generate reactive oxygen species and disinfect water. The synthesized heterostructures have inactivated pseudomonas aeruginosa, when irradiated with MW for 10 s. F. columnare inactivation is currently being studied under water quality composition, relevant to aquaculture.



SusNWaTr group has published a journal article in Sci Tot Environ, titled: "Importance of Doping, Dopant Distribution, and Nano-Scale Defects on Electronic Band Structure Alteration of Metal Oxide Nanoparticles: Implications for Reactive Oxygen Species Generation". This perspective discusses the role of dopants and defects on metal oxide nanoparticles' ability to generate ROS and introduce toxicity.



SusNWaTr group has has received funding from the National Science Foundation (NSF). The project titled: "Collaborative Research: EAGER: Interaction of Carbon-Metal Nanohybrids at Environmental Interfaces" is a collaborative effort between Drs. Saleh and Sabo-Attwood (University of Florida). This study will synthesize and complex nanohybrids and assess the role of metal crystals on nano-EHS behavior of carbon nanotube-metal oxide nanohybrids.



Erica Mason, a ChemE sophomore has won 1st place in Women in Engineering poster competition and 3rd place at the annual Poster Exhibition on Engineering Research (PEER) contest at Cockrell School of Engineering. Erica has been recognized at the Cockrell Distinguished Awards Banquet on April 20th. Indu V. Sabaraya has been closely mentoring Erica for the past semester. SusNWaTr group congratulates Erica on her achievement.



SusNWaTr group has published a journal article in Water Res, titled: "Co-transport of gold nanospheres with single-walled carbon nanotubes in saturated porous media".This study systematically assesses the transport of gold nanospheres in presence of a secondary particulate single-walled carbon nanotube. State-of-the-art characterization and saturated packed-bed column studies have been utilized to decipher underlying filtration mechanisms. Dr. A. R. M. Nabiul Afrooz, currently serving as postdoctoral scholar at the Civil and Environmental Engineering department of Stanford University, is the lead author of this paper. Senior Ph.D. student Dipesh Das is a co-author in this paper.

Abstract:Engineered nanomaterial (ENM) transport through porous media is typically assessed in a controlled single-particulate environment. Presence of a secondary particle (either natural or engineered) in the natural environment though likely, is rarely taken into consideration in assessing their transport behavior. This study systematically assesses the role of a secondary ENM (i.e., pluronic acid modified single-walled carbon nanotubes, PA-SWNTs) on a primary particle (i.e., gold nanospheres, AuNSs) transport through saturated porous media under a wide range of aquatic conditions (1-100 mM NaCl). AuNS hetero-dispersions (i.e., with PA-SWNTs) are transported through saturated sand columns and the transport behavior is compared to AuNS-only homo-dispersion cases, which display classical ionic strength-dependent behavior. AuNS hetero-dispersion, however, is highly mobile with little to no ionic strength-dependent effects. This study also assesses the role of pre-coating of the collectors with PA-SWNTs on AuNSs' mobility thus assesses the role of order of introduction of the secondary particles. Pre-existence of the secondary particles in the porous media shows enhanced filtration of primary AuNSs. However, presence of natural organic matter (NOM) slightly increases AuNS mobility through PA-SWNT coated sand at 10 mM ionic strength. The study results demonstrate that the presence and order of addition of the secondary particles strongly influence primary particles' mobility. Thus ENMs can demonstrate facilitated transport or enhanced removal, depending on the presence of the secondary particulate matter and background solution chemistry.



SusNWaTr group has published a journal article in Environ Sci Technol, titled: "Aggregation Kinetics of Higher Order Fullerene Clusters in Aquatic Systems".This is one of the first studies to systematically assesses aggregation behavior of higher order fullerene (HOF) clusters in aqueous environment. State-of-the-art characterization, dynamic light scattering, and ab initio calculations have been utilized to decipher underlying aggregation mechanisms. Dr. Nirupam Aich, currently serving as Assistant Professor at the Civil and Environmental Engineering department of SUNY Buffalo is the lead author of this paper. Senior Ph.D. student Dipesh Das and first year Ph.D. student Indu Venu Sabaraya are co-authors of this paper.

Abstract:Aggregation kinetics of nC60 and higher order fullerene (HOFs) clusters, i.e., nC70, nC76, and nC84, was systematically studied under a wide range of mono- (NaCl) and di-valent (CaCl2) electrolytes, and using time-resolved dynamic light scattering. Suwanee River Humic Acid (SRHA) was also used to determine the effect of natural macromolecule on nHOF aggregation. Increase in electrolyte concentration resulted in electrical double layer compression of the negatively charged fullerene clusters, and the nC60s and nHOFs alike displayed classical Derjaguin-Landau-Verwey-Overbeek (DLVO) type interaction. The critical coagulation concentration (CCC) displayed a strong negative correlation with the carbon number in fullerenes, and was estimated as 220, 150, 100, and 70 mM NaCl, and 10, 12, 6, and 7.5 mM CaCl2 for nC60, nC70, nC76, and nC84, respectively. The aggregation mechanism, i.e., van der Waals interaction domination, was enumerated via molecular dynamics simulation and modified DLVO model. The presence of SRHA (2.5 mg TOC/L) profoundly influenced the aggregation behavior by stabilizing all fullerene clusters, even at 100 mM NaCl concentration. The results from this study can be utilized to predict aggregation kinetics of nHOF clusters other than the ones studied here. The scaling factor for van der Waals interaction can also be used to model nHOF cluster interaction.



Nirupam Aich has successfully defended his Ph.D. dissertation titled "Environmental Implications of Higher Order Fullerenes and Conjugated Nanostructures". SusNWaTr group congratulates Dr. Nirupam Aich! Dr. Aich will be joining as a tenure-track Assistant Professor to the Department of Civil and Environmental Engineering, State University of New York, Buffalo.

Dr. Saleh has been awarded the Emerging Investigator Award of 2015, jointly sponsored by the Royal Society of Chemistry and Sustainable Nanotechnology Organization. The award was handed our at the Sustainable Nanotechnology Organization banquet dinner at the Benson Hotel, Portland, OR. The award was handed out at the Sustainable Nanotechnology Organization banquet dinner at the Benson Hotel, Portland, OR. SusNWaTr group is thankful to RSC and SNO.

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SusNWaTr group has published a journal article at Environ Sci: Nano, titled: "Defining Fundamental Science Needs: No Easy Feat when the Simple itself is Complex". This article is a in collaboration with multiple institutions. This paper discusses fundamental science needs of nanomaterial EHS.

Abstract:Nanotechnology is no longer in its infancy and has made significant advances since the implementation of the National Nanotechnology Initiative (NNI) in 2000. Incorporation of nanotechnology in many fields including information technology, medicine, materials, energy, catalysis and cosmetics has led to an increase in engineered nanomaterial (ENM) production, and consequently, increased nanomaterial use. In comparison, the generation of concrete and consistent evidence related to the environmental health and safety of nanomaterials (NanoEHS) is lacking. The main factors contributing to the slower progress in NanoEHS versus conventional EHS are related to the complexity, property transformations, life cycles and behavior of nanomaterials even in carefully controlled environments. Therefore, new systematic, integrated research approaches in NanoEHS are needed for overcoming this complexity and bridging current knowledge gaps. A workshop on "NanoEHS: Fundamental Science Needs" brought together scientists and engineers to identify current fundamental science challenges and opportunities within NanoEHS. Detailed discussions were conducted on identifying the fundamental properties that are critical in NanoEHS, differentiating between conventional and NanoEHS studies, the effect of dynamic transformations on nanometrology, role of dosimetry and mechanistic data gaps in nanotoxicology. An important realization that even simple nanoscale materials can be complex when considering NanoEHS implications was noted several times during the workshop. Despite this fact, a number of fundamental research areas to further the scientific foundation to address NanoEHS needs are suggested.



Final year PhD student, Nirupam Aich will be joining as an Assistant Professor in the Civil, Structural and Environmental Engineering Department of State University of New York at Buffalo, upon completion of his PhD dissertation from UT Austin. He has been one of the lead researchers at SusNWaTr group, publishing seven peer reviewed journal articles as the primary author (1st/2nd) and six other as co-author in high impact journals (Environ Sci Technol, Nanotechnol, ES Nano, Environ Chem, etc.). We wish him success in his future career.



SusNWaTr group has received funding from Texas Hazardous Waste Research Center (THWRC). The project titled: " Development of nanomaterial use, transport, and disposal guidelines for laboratories at the UT Austin and other THWRC consortium universities" is a collaborative effort between Drs. Saleh and Kirisits at UT Austin. This study will develop a detailed, NM-specific EHS guidelines document and safety-training module with the support of the UT-Austin EHS office.



Navajo Times, the weekly newspaper distributed throughout the Navajo reservation has recently published a story on Dr. Saleh and 2nd year graduate student Stetson Rowles III's research on nanomaterial-enhanced pottery. SusNWaTr group is developing an effective disinfection technology for the Navajo communities, where fundamental material science is integrated with the Navajo 'lifestyle knowledge' of pottery in achieving social embeddedness for the technology. This research has also been profiled in 'Alcade', the magazine of the Texas Exes.Alcade Magazine Link

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Dipesh Das, a third year PhD student of the SusNWaTr group, has been awarded the "Kolodzey Travel Grant" from the CAEE department and the "Professional Development Award" from UT Graduate School. He will be presenting his research in the upcoming 250th American Chemical Society National Meeting and Exposition, Boston, MA. Dipesh will be presenting two research projects in the conference. The titles of his presentations are- "Effect of Synthesis Chemistry on Aggregation Kinetics of CNT-Metal and CNT-Metal Oxide Nanohybrids in Environmentally Relevant Conditions" and "Co-transport of Virus Like Nanoparticles with Single-walled Carbon Nanotubes in Saturated Porous Media"



SusNWaTr group has received funding from the National Science Foundation (NSF). The project titled: "UNS: Role of dopant concentration and distribution in the environmental behavior of indium tin oxide nanoparticles" is a collaborative effort between Drs. Saleh, Kirisits, Milliron and Katz at UT Austin. This study will systematically assess the role of crystal defects and dopants on nano-EHS of indium tin oxide. The defects and dopants will be atomistically controlled.



SusNWaTr group has co-authored a journal article in a special issue (edited by Dr. Robert Tanguay) at Nanomaterials, titled: "Dynamism of Stimuli-Responsive Nanohybrids: Environmental Implications" Jaime Plazas-Tuttle, a third year PhD student, is the lead author of this article. This paper introduces novel adaptive nanohybrids and discusses the dynamism of this new class of materials during environmental interaction.

Abstract: Nanomaterial science and design have shifted from generating single passive nanoparticles to more complex and adaptive multi-component nanohybrids. These adaptive nanohybrids (ANHs) are designed to simultaneously perform multiple functions, while actively responding to the surrounding environment. ANHs are engineered for use as drug delivery carriers, in tissue-engineered templates and scaffolds, adaptive clothing, smart surface coatings, electrical switches, and in platforms for diversified functional applications. Such ANHs are composed of carbonaceous, metallic, or polymeric materials with stimuli-responsive soft-layer coatings that enable them to perform such switchable functions. Since ANHs are engineered to dynamically transform under different exposure environments, evaluating their environmental behavior will likely require new approaches. Literature on polymer science has established a knowledge core on stimuli-responsive materials. However, translation of such knowledge to environmental health and safety (EHS) of these ANHs are not yet realized. It is critical to investigate and categorize the potential hazards of ANHs because exposure in an unintended or shifting environment could present uncertainty in EHS. This article presents a perspective on EHS evaluation of ANHs, proposes a principle to facilitate their identification for environmental evaluation, outlines a stimuli-based classification for ANHs, and discusses emerging properties and dynamic aspects for systematic EHS evaluation.



SusNWaTr group has published a journal article in a special issue (edited by Dr. Boris Lau) at Frontiers in Microbiology, titled: "Mechanistic Lessons Learned from Antimicrobial Studies of Metallic Nanomaterials: Implications for Nano-Biofilm Interaction" This article is a perspective written jointly by Saleh Group and Kirisits Group at UT's EWRE program. This paper discusses unique mechanisms of nanoparticle interaction with attached microbiological systems.

Abstract: Metal and metal oxide nanoparticles (NPs) are used in numerous applications and have high likelihood of entering engineered and natural environmental systems. Careful assessment of the interaction of these NPs with bacteria, particularly biofilm bacteria, is necessary. This perspective discusses mechanisms of NP interaction with bacteria and identifies challenges in understanding NP-biofilm interaction, considering fundamental material attributes and inherent complexities of biofilm structure. The current literature is reviewed, both for planktonic bacteria and biofilms; future challenges and complexities are identified, both in light of the literature and a dataset on the toxicity of silver NPs toward planktonic and biofilm bacteria. This perspective aims to highlight the complexities in such studies and emphasizes the needs for systematic evaluation of NP-biofilm interaction.



SusNWaTr group has co-authored a journal article in a special issue (edited by Dr. Robert Tanguay) at Nanomaterials, titled: "Examination of single-walled carbon nanotubes uptake and toxicity from dietary exposure: Tracking movement and impacts in the gastrointestinal system" This article resulted from the collaborative research of Sabo-Attwood (University of Florida) and Saleh groups. The paper presents novel experimental results on nutrient sorption to single-walled carbon nanotubes via analysis of gene expressions and studying histology of fathead minnows (Pimephales promelas ), and performing detailed physiochemical characterization of the materials.

Abstract: Previous studies indicate that exposure of fish to pristine single-walled carbon nanotubes (SWCNTs) by oral gavage causes no overt toxicity and no appreciable absorption has been observed. However, in the environment, SWCNTs are likely to be present in dietary sources, which may result in differential impacts on uptake and biological effects. Additionally, the potential of these materials to sorb nutrients (proteins, carbohydrates, and lipids) while present in the gastrointestinal (GI) tract may lead to nutrient depletion conditions that impact processes such as growth and reproduction. To test this phenomenon, fathead minnows were fed a commercial diet either with or without SWCNTs for 96 hours. Tracking and quantification of SWCNTs using near-infrared fluorescence (NIRF) imaging during feeding studies showed the presence of food does not facilitate transport of SWCNTs across the intestinal epithelia. Targeting genes shown to be responsive to nutrient depletion (peptide transporters, peptide hormones, and lipases) indicated that pept2 , a peptide transporter, and cck , a peptide hormone, showed differential mRNA expression by 96 hours, a response that may be indicative of nutrient limitation. The results of the current study increase our understanding of the movement of SWCNTs through the GI tract, while the changes in nutrient processing genes highlight a novel mechanism of sublethal toxicity in aquatic organisms.



Dr. A.R.M. Nabiul Afrooz has successfully defended his doctoral dissertation titled: "Aggregation and Deposition of Gold Nanoparticles (AuNP) in Singular and Binary Systems: Role of Size, Shape, and Environmental Characteristics". Dr. Afrooz has already published 16 journal articles and 2 book chapters with 2 more journal articles under review. He will be joining as a post-doctoral scholar in Professor Alexandria Boehm's research group at Stanford University. Congratulations Dr. Afrooz!.

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Dr. Saleh will be presenting an invited lecture to the Department of Environmental and Global Health at University of Florida on March 13, 2015 at 9:00 am (Emerging Pathogens Institute, Room 150). His Talk is titled: "Environmental behavior of nanomaterials: Implications of material and environmental complexities". SusNWaTr Group thanks the gracious host, Dr. Tara Sabo-Attwood.



Final year PhD student, A.R.M. Nabiul Afrooz will be joining Professor Alexandria Boehm's research group at Stanford University, upon completion of his PhD dissertation from UT Austin. He has been one of the lead researchers at SusNWaTr group, publishing six primary authored (1st/2nd) and ten other co-authored peer reviewed articles in high impact journals (Environ Sci Technol, Chemosphere, J Nanopart Res, etc.). We wish him success in his future career.



SusNWaTr group's recently accepted paper in ES Nano, titled: "Research Strategy to Determine When Novel Nanohybrids Pose Unique Environmental Risks" has been featured in the journal's cover; Issue 1, Volume 2, pp 11-18.

Abstract: The production and use of increasingly complex hierarchical multifunctional ensembles of nanomaterials introduces emergent properties that will likely lead to uncertainty in the environmental health and safety (EHS) evaluation of nanohybrids (NHs). This perspective proposes principles to identify NHs with novel properties relevant to nano EHS research, and discusses specific challenges for EHS research on these materials. We propose a strategy for focusing nano EHS research efforts on relevant NH systems.



SusNWaTr Group has published a journal article in Environ Chem, titled: "Change in Chirality of Semiconducting Single-Walled Carbon Nanotubes Can Overcome Anionic Surfactant Stabilization: A Systematic Study of Aggregation Kinetics". The article assesses the interplay between anionic surfactant structure and chirality of single-walled carbon nanotubes on their aggregation behavior. Time-resolved state-of-the-art characterization, dynamic light scattering, and ab initio calculations have been utilized to decipher underlying aggregation mechanisms.

Abstract: Single-walled carbon nanotubes' (SWNT) effectiveness in applications is enhanced by debundling or stabilization. Anionic surfactants are known to effectively stabilize SWNTs. However, the role of specific chirality on surfactant-stabilized SWNT aggregation has not been studied to date. The aggregation behavior of chirally enriched (6,5) and (7,6) semiconducting SWNTs, functionalized with three anionic surfactants-sodium dodecyl sulfate (SDS), sodium dodecyl benzene sulfonate (SDBS), and sodium deoxycholate (SDOCO)-was evaluated with time-resolved dynamic light scattering. A wide range of mono- (NaCl) and di-valent (CaCl2) electrolytes as well as a 2.5 mg TOC/L Suwannee River humic acid (SRHA) were used as background chemistry. Overall, SDBS showed the most effectiveness in SWNT stability, followed by SDOCO and SDS. However, the relatively larger diameter (7,6) chiral tubes compromised the surfactant stability, compared to (6,5) chiral enrichment, due to enhanced van der Waals interaction. The presence of di-valent electrolytes overshadowed the chirality effects and resulted in similar aggregation behavior for both the SWNT samples. Molecular modeling results enumerated key differences in surfactant conformation on SWNT surfaces and identified interaction energy changes between the two chiralities to delineate aggregation mechanisms. The stability of SWNTs increased in the presence of SRHA under 10 mM monovalent and mixed electrolyte conditions. The results suggest that change in chirality can overcome surfactant stabilization of semiconducting SWNTs. SWNT stability can also be strongly influenced by the anionic surfactant structure.



SusNWaTr group's recently accepted paper in Environ Chem, "A Critical Review of Nanohybrids: Synthesis, Applications, and Environmental Implications" has been featured in the journal's cover; Issue 6, Volume 11, pp 609-623. This review presents a critical discussion on synthesis, applications, and altered physicochemical properties of nanohybrids and highlights the potential environmental implications of these 'horizon materials'.

Abstract: Nanomaterial synthesis and modification for applications have progressed to a great extent in last decades. Manipulation of physicochemical properties of a material at the nano-scale has been extensively performed to produce materials in novel applications. Controlling size, shape, surface functionality, etc. have been key to successful implementation of nanomaterials in multidimensional usage for electronics, optics, biomedical, drug delivery, and green fuel technology. Recently, focus has been on the conjugation of two or more nanomaterials to achieve increased multifunctionality as well as creating opportunities for next generation materials with enhanced performance. With incremental production and potential usage of such nanohybrids come the concerns about their ecological and environmental impact which will be dictated by their not-yet-understood physicochemical properties. While environmental implication studies concerning the single materials are yet to give an integrated mechanistic understanding and predictability in their environmental fate and transport, the importance of studying the novel nanohybrids with their multi-dimensional and complex behavior in environmental and biological exposure systems are immense. This article critically reviews nanohybrids literature and identifies potential environmental uncertainties of these emerging 'horizon materials'.



Saleh Group has published a journal article in Environ Sci: Nano, titled: "Research Strategy to Determine When Novel Nanohybrids Pose Unique Environmental Risks". Dr. Saleh is the lead author of this article. The article identifies principles to discern environmentally relevant conjugated nanomaterial or nahohybrid identity and presents new insights and strategies into nanohybrid EHS.

Abstract: The production and use of increasingly complex hierarchical multifunctional ensembles of nanomaterials introduces emergent properties that will likely lead to uncertainty in the environmental health and safety (EHS) evaluation of nanohybrids (NHs). This perspective proposes principles to identify NHs with novel properties relevant to nano EHS research, and discusses specific challenges for EHS research on these materials. We propose a strategy for focusing nano EHS research efforts on relevant NH systems.



Saleh Lab has received funding from Texas Department of Transportation (TxDOT). The project is titled: "Effectively Dispersed Carbon Nanotube Enhanced Asphalt: Novel Foamed Delivery and Traditional Mixing Techniques". Dr. Saleh is the PI of the project with co-PI Dr. Amit Bhasin (CAEE). The Saleh Lab will perform nanotube functionalization and evaluate dispersion quality in asphalt.



Saleh Group has published a journal article in J Nanopart Res, titled: "Aggregate size and structure determination of nanomaterials in physiological media: Importance of dynamic evolution". 5th year PhD student A. R, M. Nabiul Afrooz is the lead author of this article. The article presents new insight into nanomaterial aggregate size and structure formation under biologically relevant media via continuous time-dependent measurements. The findings of this article may have profound implications on effective dosimetry and on time of in vitro nanotoxicity assays.

Abstract: Most in vitro nanotoxicological assays are performed after 24 h exposure. However, in determining size and shape effect of nanoparticles in toxicity assays, initial characterization data is generally used to describe experimental outcome. The dynamic size and structure of aggregates are typically ignored in these studies. This brief communication reports dynamic evolution of aggregation characteristics of gold nanoparticles. The study finds that gradual increase in aggregate size of gold nanospheres (AuNS) occurs up to 6 h duration; beyond this time period, the aggregation process deviates from gradual to a more abrupt behaviour as large networks are formed. Results of the study also show that aggregated clusters possess unique structural conformation depending on nominal diameter of the nanoparticles. The differences in fractal dimensions of the AuNS samples likely occurred due to geometric differences, causing larger packing propensities for smaller sized particles. Both such observations can have profound influence on dosimetry for in vitro nanotoxicity analyses.



Dr. Saleh will be presenting an invited lecture to Civil and Environmental Engineering of University of Illinois at Urbana Champaign on October 16, 2014 at 12:00 pm (1518 Hydro). His Talk is titled: "Environmental behavior of nanomaterials: Implications of material and environmental complexities". Saleh Group thanks the gracious host, Dr. Helen Nguyen.



Saleh Group has published a journal article in Part Fibre Toxicol, titled: "Single-walled carbon nanotubes increase pandemic influenza A H1N1 virus infectivity of lung epithelial cells". 5th year PhD student A. R, M. Nabiul Afrooz is a co-author of this article; which presents new insight into nanomaterial-virus interaction and its implication on virus infectability.

Abstract: The extraordinary physico-chemical properties that make nanomaterials promising for product enhancement applications may lead to adverse health effects from unintended occupational or environmental exposures. We have investigated the ability of pristine single-walled carbon nanotubes (SWCNTs) of diverse electronic structure to increase the susceptibility of small airway epithelial cells (SAEC) to influenza A H1N1 infection. For the first time, we report that pre-treatment of SAEC with SWCNTs significantly enhances viral infectivity that is not dependent on SWCNT electronic structure and aggregate size within the average range of 106 nm-243 nm. We further provide evidence to support that this altered infectivity in not likely due to direct interaction of the virus and nanoparticles, but rather a suppression of pro-inflammatory (RANTES) and anti-viral (ITIF2, ITIF3) gene expression by SWCNT. Overall results of this work reveal the potential for SWCNT to increase susceptibility to viral infections as a mechanism of adverse effect.



Dr. Saleh will be presenting an invited lecture to Civil and Environmental Engineering of Cornell University on October 02, 2014 at 4:30 pm (110 Hollister Hall). His Talk is titled: "Environmental behavior of nanomaterials: Implications of material and environmental complexities". Saleh Group thanks the gracious host, Dr. Damian Helbling.

Dr. Saleh will be presenting an invited lecture to Civil and Environmental Engineering of Rice University on September 19, 2014 at 2:00 pm (Ryon Lab, 201). His Talk is titled: "Environmental behavior of nanomaterials: Implications of material and environmental complexities". Saleh Group thanks the gracious hosts, Drs. Alvarez and Li.

Saleh Lab has received funding from the National Science Foundation (NSF). The project titled: "NUE: Sustainable Nanotechnology Education for Undergraduate Engineering Students" will establish two new courses on nanotechnology at UT Austin. Drs. Mary Jo Kirisits and Hillary Hart of EWRE and Brian Korgel from Chemical Engineering are co-PIs in this project.

Saleh Group has published a journal article in Environmental Chemistry, titled: "A Critical Review of Nanohybrids: Synthesis, Applications, and Environmental Implications". 5th year PhD student Nirupam Aich is the lead author of this review, which presents a critical discussion on synthesis, applications, and altered physicochemical properties of nanohybrids and highlights the potential environmental implications of these 'horizon materials'.

Abstract: Nanomaterial synthesis and modification for applications have progressed to a great extent in last decades. Manipulation of physicochemical properties of a material at the nano-scale has been extensively performed to produce materials in novel applications. Controlling size, shape, surface functionality, etc. have been key to successful implementation of nanomaterials in multidimensional usage for electronics, optics, biomedical, drug delivery, and green fuel technology. Recently, focus has been on the conjugation of two or more nanomaterials to achieve increased multifunctionality as well as creating opportunities for next generation materials with enhanced performance. With incremental production and potential usage of such nanohybrids come the concerns about their ecological and environmental impact which will be dictated by their not-yet-understood physicochemical properties. While environmental implication studies concerning the single materials are yet to give an integrated mechanistic understanding and predictability in their environmental fate and transport, the importance of studying the novel nanohybrids with their multi-dimensional and complex behavior in environmental and biological exposure systems are immense. This article critically reviews nanohybrids literature and identifies potential environmental uncertainties of these emerging 'horizon materials'.

Saleh Group has published a journal article in Nanomaterials for its special issue on "Nanotoxicology" (Editor: Robert Tanguay), titled: "Emergent Properties and Toxicological Considerations for Nanohybrid Materials in Aquatic Systems". This review article has been written jointly with Dr. Tara Sabo-Attwood's group at University of Florida. The article presents a critical discussion on altered physicochemical properties of nanohybrids and analyzes the validity of existing nanotoxicology paradigms against these unique properties.

Abstract: Conjugation of multiple nanomaterials has become the focus of recent materials development. This new material class is commonly known as nanohybrids or 'horizon nanomaterials'. Conjugation of metal/metal oxides with carbonaceous nanomaterials and overcoating or doping of one metal with another, have been pursued to enhance material performance and/or incorporate multifunctionality into nano-enabled devices and processes. Nanohybrids are already at use in commercialized energy, electronics, and medical products, which warrant immediate attention for their safety evaluation. These conjugated ensembles likely present a new set of physicochemical properties that are unique to their individual component attributes, hence increasing uncertainty in their risk evaluation. Established toxicological testing strategies and enumerated underlying mechanisms will thus need to be re-evaluated for assessment of these horizon materials. This review will present a critical discussion on altered physicochemical properties of nanohybrids and analyze the validity of existing nanotoxicology paradigms against these unique properties. The article will also propose strategies to evaluate the conjugate materials safety to help undertake future toxicological research on the nanohybrid material class.

Saleh Group has published a book chapter titled: "Roles of Geo- and Bio-Macromolecules on Environmental Interactions of Nanomaterials" in Bio-inspired Nanotechnology-From Surface Analysis to Applications. This chapter discusses nanomaterial interaction with geo- and bio-macromolecules in the environment.

Abstract: Engineered nanomaterials (ENMs) are mostly synthesized with modified surfaces using various surfactants, polymeric, or biomolecule coatings to achieve desired functionality. When exposed to the environment, coatings on the ENMs will undergo the first set of interactions with natural geo- and bio-macromolecules, pre-existing in aqueous and/or soil matrices. Such interfacial interaction will likely alter the conformation and extent of coverage of the synthetic ENM surface coatings via exchange, displacement, and/or overcoating by environmental macromolecules. The exchange kinetics and extent of replacement of the synthetic coatings will profoundly impact environmental fate, transport, transformation, and toxicity of the ENMs. This chapter discusses the state of the art literature to identify key synthetic coating types, their interaction with the environmental and biological macromolecules, and illustrate the existing challenges to determine coating exchange kinetics and its environmental implications on ENMs.

Saleh Group has published a journal article in Journal of Intelligent Material Systems and Structures titled: "Detection of Crack Formation and Stress Distribution for Carbon Fiber Reinforced Polymer Specimens through Triboluminescent-Based Imaging". Fifth year PhD student, Nirupam Aich is the lead author in this paper. The article presents a simple and novel method to detect time evolution and stress distribution during compressive loading on CFRP matrices using a triboluminescent material.

Abstract: This article demonstrates the ability of surface coated triboluminescent (TL) materials to detect damage in carbon fiber reinforced polymer (CFRP) specimens. An experimental protocol was developed to test the efficiency of the TL-based diagnostic method using CFRP coupons under combined bending-compression conditions. Luminescence, emitted from the TL coatings under quasi-static loading, was detected by capturing digital images. We employed image processing software to quantify change in luminescence as a function of TL concentration. We observed that 10, 20, and 30% TL coating resulted in 25.3, 27.9, and 40.4 (arbitrary units) total luminescence, respectively; which shows a positive correlation of TL concentration with luminescence. Finite element simulation was also performed to understand the stress and strain distribution and to aid in understanding and correlating light emission regions on the CFRP coupons under bending deformation. The current work represents a step toward the development of a robust technology that employs TL material for early damage detection, consistent with theoretical predictions of damage occurrence.

Full Paper

The article titled "Triboluminescence for distributed damage assessment in cement-based materials" published by Saleh group has been featured as one of 2013's top 5 most read papers in J Intell Mater Syst Struct. Fifth year PhD student, Nirupam Aich is the lead author of this paper. The article presents a simple and novel imaging technique for distributed crack sensing in cementitious matrices using a triboluminescent material.

Full Paper



Nirupam Aich, a 5th year PhD student in the Saleh Group has been awarded the prestigious American Chemical Society (ACS) Environmental Chemistry Graduate Student Award 2014. Nirupam competed nationally with the top environmental engineering graduate students to win this award. Award was based upon students' records in course work, evidence of research productivity and recommendations from graduate faculty advisor. Primary emphasis is given to Nirupam's potential for future contributions as professionals in environmental chemistry. Nirupam will receive a check from ACS Environmental Chemistry Division and his Institution's, and advisor's names will be posted on the ACS website for one full year. Congratulations Nirupam!

Saleh Group has co-authored a journal article in Environmental Science and Technology titled: "Tracking and Quantification of Single-walled Carbon Nanotubes in Fish Using Near Infrared Fluorescence". ARM Nabiul Afrooz, a fourth year PhD student also co-authored this paper. The article tracks SWCNTs in fathead minnows using near infrared fluorescence spectroscopy; toxicity from SWCNTs was also evaluated. The work is funded by the CBET program of NSF.

Abstract: Detection of SWCNTs in complex matrices presents a unique challenge as common techniques lack spatial resolution and specificity. Near infrared fluorescence (NIRF) has emerged as a valuable tool for detecting and quantifying SWCNTs in environmental samples by exploiting their innate fluorescent properties. The objective of this study was to optimize NIRF-based imaging and quantitation methods for tracking and quantifying SWCNTs in an aquatic vertebrate model in conjunction with assessing toxicological endpoints. Fathead minnows (Pimephales promelas) were exposed by single gavage to SWCNTs and their distribution was tracked using a custom NIRF imaging system for 7 days. No overt toxicity was observed in any of the SWCNT treated fish; however, histopathology observations from gastrointestinal (GI) tissue revealed edema within the submucosa and altered mucous cell morphology. NIRF images showed strong SWCNT-derived fluorescence signals in whole fish and excised intestinal tissues. Fluorescence was not detected in other tissues examined, indicating that no appreciable intestinal absorption occurred. SWCNTs were quantified in intestinal tissues using a NIRF spectroscopic method revealing values that were consistent with the pattern of fluorescence observed with NIRF imaging. Results of this work demonstrate the utility of NIRF imaging as a valuable tool for examining uptake and distribution of SWCNTs in aquatic vertebrates.

Saleh Group has co-authored a journal article in Environmental Science and Technology titled: "Effects of Chloride and Ionic Strength on Physical Morphology, Dissolution, and Bacterial Toxicity of Silver Nanoparticles". ARM Nabiul Afrooz and Nirupam Aich also co-authored this paper. This work is a result of successful collaboration with Dr. Mary J Kirisits' group at UT Austin. The article studies role of chloride at controlled ionic strength conditions on toxicity of silver nanoparticles (AgNPs). The paper elucidates mechanisms of toxicity using aggregation state, fractal dimension, morphology, and dissolution properties of AgNPs.

Abstract: In this study, we comprehensively evaluate chloride- and ionic-strength-mediated changes in the physical morphology, dissolution, and bacterial toxicity of silver nanoparticles (AgNPs), which are one of the most-used nanomaterials. The findings isolate the impact of ionic strength from that of chloride concentration. As ionic strength increases, AgNP aggregation likewise increases (such that the hydrodynamic radius [HR] increases), fractal dimension (Df) strongly decreases (providing increased available surface relative to suspensions with higher Df), and the release of Ag(aq) increases. With increased Ag+ in solution, Escherichia coli demonstrates reduced tolerance to AgNP exposure (i.e., toxicity increases) under higher ionic strength conditions. As chloride concentration increases, aggregates are formed (HR increases) but are dominated by AgCl0(s) bridging of AgNPs; relatedly, Df increases. Furthermore, AgNP dissolution strongly increases under increased chloride conditions, but the dominant, theoretical, equilibrium aqueous silver species shift to negatively charged AgClx(x-1)- species, which appear to be less toxic to E. coli. Thus, E. coli demonstrates increased tolerance to AgNP exposure under higher chloride conditions (i.e., toxicity decreases). Expression measurements of katE, a gene involved in catalase production to alleviate oxidative stress, support oxidative stress in E. coli as a result of Ag+ exposure. Overall, our work indicates that the environmental impacts of AgNPs must be evaluated under relevant water chemistry conditions.



A workshop on problem-based learning for nanotechnology has successfully been arranged by Drs. Saleh, Caicedo, and Pierce at USC. Eminent scholars in the fields of nanotechnology, society and technology, and education attended the workshop. The workshop is an outcome of the NSF grant, funded by Dr. Mary Poats' NUE program. This workshop had been extremely exciting and resulted in stimulating discussions at the interface of nanotechnology and society. Saleh Lab sincerely thanks the participants and expects to continue to contribute in the field of nano-education with the support of Drs. Caicedo and Pierce and the respected participants.

Saleh Group has published a journal article in Nanotechnology titled: "Preparation of Non-Aggregating Aqueous Fullerenes in Highly Saline Solutions with A Biocompatible Non-Ionic Polymer". Nirupam Aich, fourth year PhD student is the lead author in this paper. The article prepares non-aggregating nC60s and nC70s using a bio-compatible polymeric coating.

Abstract: Size-tunable stable aqueous fullerenes were prepared with different concentrations of biocompatible block-copolymer pluronic (PA) F-127, ranging from 0.001% to 1% (w/v). Size uniformity increased with the increase in PA concentration, yielding optimum 58.8+/-5.6 and 61.8+/-5.6 nm nC60s and nC70s, respectively (0.10 %w/v PA), as observed using dynamic light scattering technique. Fullerene aqueous suspensions also manifested enhanced stability in saline solution, Dulbecco's Modified Eagle Medium (DMEM), and Roswell Park Memorial Institute (RPMI) culture medium. Transmission electron microscopy was performed to elaborate on the morphology and size specificity of fullerene clusters. Physicochemical characterizations of the suspended fullerenes were performed through UV-Vis spectroscopy and electrophoretic mobility measurements. PA molecules showed size restriction by encasement, as observed via molecular dynamic simulation. Such solubilization with controllable size and non-aggregating behavior can facilitate application-enhancement and mechanistic environmental and toxicological studies of size-specific fullerenes.

Saleh Lab has been awarded a grant by Nano Environmental Health and Safety Program at the National Science Foundation (NSF). The project is titled: "Collaborative Research: Fate, Transport, and Organismal Uptake of Rod-Shaped Nanomaterials". It is a three-way collaborative effort between Dr. Saleh, Dr. Vikesland of Virginia Tech, and Dr. Murphy of University of Illinois-Urbana Champaign. The Saleh Lab will evaluate the role of aspect ratio on aggregation and deposition behavior of nanomaterials.

Saleh Group has published a journal article in Chemosphere titled: "Fractal Structures of Single-Walled Carbon Nanotubes in Biologically Relevant Conditions: Role of Chirality vs. Media Conditions". Recently graduated PhD student, Iftheker A Khan is the lead author in this paper. The article evaluates fractal dimension of single-walled carbon nanotubes in biological media conditions and studies the role of chirality on fractal structure formation.

Abstract: Aggregate structure of covalently functionalized chiral specific semiconducting single-walled carbon nanotubes (SWNTs) was systematically studied employing static light scattering (SLS). Fractal dimensions (Df) of two specific chirality SWNTs- SG65 and SG76 SWNTs with (6, 5) and (7, 6) chiral enrichments - were measured under four biological exposure media conditions, namely: Dulbecco's modified eagle medium (DMEM), minimum essential medium (MEM), Roswell Park Memorial Institute (RPMI) 1640 medium, and 0.9% saline solution. The SWNTs exhibited chiral dependence on Df with SG65 showing more fractal or loosely bound aggregate structures, i.e., lower Df values (range of 2.24+/-0.03 to 2.64+/-0.05), compared to the SG76 sample (range of 2.58+/-0.13 to 2.90+/-0.08). All the Df values reported are highly reproducible, measured from multiple SLS runs and estimated with 'random block-effects' statistical analysis that yielded all p values to be <0.001. The key mechanism for such difference in Df between the SWNT samples was identified as the difference in van der Waals (VDW) interaction energies of these samples, where higher VDW of SG76 resulted in tighter packing density. Effect of medium type showed lower sensitivity; however, presence of di-valent cations (Ca2+) in DMEM and MEM media resulted in relatively loose or more fractal aggregates. Moreover, presence of fetal bovine serum (FBS) and bovine serum albumin (BSA), used to mimic the in-vitro cell culture condition, reduced the Df values, i.e., created more fractal structures. Steric hindrance to aggregation was identified as the key mechanism for creating the fractal structures. Also, increase in FBS concentration from 1% to 10% resulted in increasingly lower Df values.

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Saleh Group has published a journal article in Environmental Science and Technology titled: "Single-Walled Carbon Nanotube Transport in Representative Municipal Solid Waste Landfill Conditions". Recently graduated PhD student, Iftheker A Khan is the lead author in this paper. The article studies transport of single-walled carbon nanotubes in complex landfill conditions. This study is a result of a successful collaboration of the Saleh Lab with Dr. Berge's municipal solid waste research.

Abstract: Single-walled carbon nanotubes (SWNTs) are being used in many consumer products and devices. It is likely that as some of these products reach the end of their useful life, they will be discarded in municipal solid waste landfills. However, there has been little work evaluating the fate of nanomaterials in solid waste environments. The purpose of this study is to systematically evaluate the influence of organic matter type and concentration in landfill-relevant conditions on SWNT transport through a packed-bed of mixed municipal solid waste (MSW) collectors. The influence of individual waste materials on SWNT deposition is also evaluated. Transport experiments were conducted through saturated waste-containing columns over a range of simulated leachate conditions representing both mature and young leachates. Results indicate that SWNT transport may be significant in mature waste environments, with mobility decreasing with decreasing humic acid concentration. SWNT mobility in the presence of acetic acid was inhibited, suggesting their mobility in young waste environments may be small. SWNTs also exhibited collector media-dependent transport, with greatest transport in glass and least in paper. These results represent the first study evaluating how leachate age and changes in waste composition influence potential SWNT mobility in landfills.

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Saleh Group has published an article on nanotechnology education in the Journal of Nano Education. The title of the article is: "Nano in a Global Context: Modular Course Design with Integrated Ethics Improves Core Knowledge in Nanotechnology". Dr. Saleh is the lead author in this article. USC's Drs. Juan Caicedo (Civil and Environmental Engineering) and Ann Johnson (History and Philosophy) are the other lead authors in this article. This article is the first in a series of education based papers that resulted from Saleh Group's NSF grant on nanotechnology edcaution.

Abstract: A problem-based learning (PBL) course was designed to teach the principles and application of nanotechnology through a real-world problem of global significance: water decontamination. The novel course design also attempted a close integration of social and ethical component of nanotechnology through a weekly lecture on these aspects, in parallel to the technical component. Overall the course pursued three principal goals: introduce nanotechnology to engineering students who otherwise have no formal exposure to this emerging technology; integrate the approaches pertaining to nanotechnology offered by different engineering disciplines; and fully incorporate discussions about the practical ethical implications of implementing nano in a real, developing world context. In this endeavor, the course structure was based on introductory modules discussing fundamental principles of nanotechnology as well as key issues related to water contamination in developing countries. Four inquiry-based modules followed the introductory segment engaged students in learning nanotechnology principles to solve water contamination issues, namely: arsenic removal, virus detection, mechanical sensing, and detection of arsenic. Assessment conducted via pre- and post-tests and a survey using a nanotechnology concept inventory show substantial gain in core knowledge. It is believed that the PBL based course design alongside with the integrated social and ethical component encouraged the students to learn and apply the principles of nanotechnology toward a real-life social problem. The ethical perspective has likely reinforced the purpose of learning and thus has resulted in an enhanced learning experience.



Dr. Saleh has officially accepted a faculty position at the department of Civil, Architectural and Environmental Engineering (CAEE), Cockrell School of Engineering, University of Texas at Austin. He will join there in January 2014. Saleh Lab will continue the ongoing research at USC and ensure a seamless transition to UT Austin. We thank the support of all the funding agencies (NSF, NIH, USAF, SCDOT, GSE&C), and collaborators for enabling to establish a successful research program.

Saleh Group has co-authored an article published in Il Nuovo Cimento C, a journal published by Italian Physical Society. The title of the paper is: "Nanoparticle dynamics in the presence and absence of a cellular uptake altering chemical". Fourth year PhD student, A. R. M. Nabiul Afrooz is a co-author in this paper. The article is a result of the collaboration between the Saleh Lab and Dr. Saber Hussain of AFRL.

Abstract: The far-reaching applications of nanoparticles (NPs) in drug delivery, medical imaging, diagnostics, and therapeutics have led to an increased potential for interfacing with a diverse range of biological environments. While metallic NPs such as copper NPs have been explored for their antimicrobial and catalytic properties, they have been shown to induce undesirable toxic effects. Nonetheless, biomodulators may be employed to control this cytotoxicity. Dynasore is a dynamin GTPase inhibitor that has been shown to rapidly and reversibly block clathrindependent endocytic traffic within minutes of application. Here, we demonstrate that Dynasore can chemically bio-modulate the toxic effects of copper nanoparticles (Cu NPs), but not through reducing Cu NP internalization. In fact, Dynasore seems to possess secondary effects that have been unreported to date. We propose and test three potential mechanisms of cytotoxicity modulation: 1) through changes in agglomeration pattern, 2) through potential quenching of reactive oxygen species (ROS), and 3) through Cu+2 ion chelation. These results have far-reaching implications for understanding the complex interactions that occur at the interface of NPs in biological environments, especially during mechanistic chemical modification strategies.


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Saleh Group has published a journal article in Environmental Science and Technology titled: "Mechanistic Hetero-aggregation of Gold Nanoparticles in a Wide Range of Solution Chemistry". Third year PhD student, ARM Nabiul Afrooz is the lead author in this paper. The article studies aggregation of gold nanospheres in presence of non-ionic polymeric surfactant coated single-walled carbon nanotubes in a wide range of solution chemistry.

Saleh Group has published a journal article in Environmental Science and Technology titled: "Chirality Affects Aggregation Kinetics of Single-Walled Carbon Nanotubes". Recently graduated PhD student, Iftheker A Khan is the lead author in this paper. The article studies the role of chirality on aggregation of single-walled carbon nanotubes.

ARM Nabiul Afrooz, a 3rd year PhD student in the Saleh Group has been awarded the prestigious American Chemical Society (ACS) Environmental Chemistry Graduate Student Award 2013. Nabiul competed nationally with the top environmental engineering graduate students to win this award. Award was based upon students' records in course work, evidence of research productivity and recommendations from graduate faculty advisor. Primary emphasis is given to Nabiul's potential for future contributions as professionals in environmental chemistry. Nabiul will receive a check from ACS Environmental Chemistry Division and his Institution's, and advisor's names will be posted on the ACS website for one full year. Congratulations Nabiul!

A R M Nabiul Afrooz, a third year PhD student in the Saleh Group has been awarded the Bert Storey Fellowship, 2012-2013. This fellowship is awarded by Civil and Engineering Department of the College of Engineering and Computing in USC to the top civil and environmental graduate student. The fellowship is named after Mr. Bert Storey, a long time patron of the University. Nabiul will receive an honorarium to support his research activities. Congratulations Nabiul!

Nirupam Aich, a 4th year PhD student in the Saleh Group, has been awarded the Support to Promote Research and Creativity (SPARC) Graduate Research Fellowship. He is one of the first recipients of this fellowship and the only environmental engineering graduate student awardee, to receive this prestigious fellowship awarded by the Office of the Vice President for Research. The $5000 SPARC fellowship, which rewards excellence in graduate student grant writing and creativity in research, will benefit Nirupam's dissertation and other academic activities.

Saleh Group has published a journal article in Journal of Intelligent Material Systems and Structures titled: "Triboluminescence for Distributed Damage Assessmentin Cement Based Materials". Third year PhD student, NirupamAich is the lead author in this paper. The article presents a simple and novel method to detect crack on cementitious matrices using a triboluminescent material.

Abstract: Triboluminescent (TL) materials are promising in the field of Structural Health Monitoring (SHM) for real time crack detection and related damage assessment. This study presents a simple, however novel, image processing protocol to detect and quantify luminescence from crack-formation in cement based matrices. 2" × 2" (5.1 cm x 5.1 cm)mortar cubes were loaded in compression with an external coating of manganese doped zinc sulfide (ZnS:Mn) TL material. The concentration of TL material and rate of loading were varied to evaluate luminescence response. A DSLR camera was employed to capture luminescence from the resulting cracks which formed and propagated during failure. The images were then analyzed with an image processor and total luminescence/pixel along the cracks was quantified. Results show that overall luminescence increase with the increase in TL concentration as well as with the rate of loading. This article presents a novel method that can be applied to monitor crack formation in cement based materials, providing reliable accuracy in luminescence quantification.

Dr Saleh's poster titled "Mechanistic hetero-aggregation of gold nanoparticles for a Wide Range of Solution chemistries" has been awarded Honorable Mention at the 1st Sustainable Nanotechnology Conference, Arlington, VA. The award was announced on Nov 6, 2012 and has recently been listed in Sustainable Nanotechnology's February newsletter. This poster presented the results of a recently published paper in ES&T. Please refer to the published article here.

Dr. Saleh has held an outreach effort at the Dutch Fork High School, Irmo, SC. The outreach involved a seminar on nanotechnology, followed by an activity on 'surface area to volume ratio' using fullerene models. Dr. Saleh extended this outreach through Dutch Fork High School's Physical Sciences Honors course (Course No.: 3211STHW) with 48 freshmen. This activity will be repeated at the end of this month. A more extensive outreach effort involving a three class series with lectures, hands on activities, and EM via Skype program will be executed over Spring 2013.

Society of Toxicology (SOT) has inducted Dr. Saleh as a full member. Dr. Saleh is honored with the induction and will be deeply involved in the SOT activities. The first of such activities is a professional course offering by Dr Saleh titled: 'Aggregation Behavior of Nanomaterials Under Biological Exposure Conditions' at the 52nd SOT Annual Meeting from March 10-14, 2013 at San Antonio, TX.

Saleh Group has published a journal article in J Res Updates in Poly Sci titled: "Applied TEM Approach for Micro/Nanostructural Characterization of Carbon Nanotube Reinforced Cementitious Composites". 3rd year graduate student Nirupam Aich is the lead author in this paper. The article presents a novel approach to perform electron microscopy on complex cementitious composite matrices to characterize carbonaceous nanomaterial and cement matrix compatibility. This article is the first in the series of articles in the making on Saleh Group's collaborative effort with Drs. Ziehl and Matta at USC.

Dr. Iftheker A Khan has successfully defended his doctoral dissertation work titled: "Aggregation Behavior of Chiral Single-Walled Carbon Nanotubes and Their Transport in Landfill Conditions". Dr. Khan has already published 5 journal articles with 4 more under review. His achievements has earned him a post-doctoral position at the National Center for Toxicological Research (NCTR) at Little Rock, AR. Congratulations Dr. Khan!

NCTR

Saleh Lab has received an R01 funding from the National Institute of Health (NIH). The project titled: "Contribution of Toll-like Receptors in the Pulmonary Response to Nanoparticles and Pathogens" is a collaborative effort with Dr. Tara Sabo-Attwood at the University of Florida. The Saleh Lab will evaluate nanotube-virus interfacial interaction to study the mechanisms of immune signals of lung epithelial cells triggered by the pathogenic and particulate entities.

Iftheker A khan, a final year PhD student in the Saleh Group has been chosen as the 2012 USC Graduate School Summer Dissertation Fellow. This fellowship is awarded by the University of South Carolina Graduate School and only four students in the entire university is bestowed with such an honor. Iftheker's excellent academic record and exemplary research performance has earned him this honor. As part of this fellowship, Iftheker will receive a $2,500 financial award toward his graduation and dissertation completion. Congratulations Iftheker!

Samuel P. Rollings, a senior at USC and a Magellan Scholar working in Saleh Lab has won the 1st prize at Discovery Day. The title of his poster was "Modular Nano-enabled Sorption Cartridge for Water Treatment". This work is focused on developing a simply yet novel technique to coat filter surfaces with advanced nanomaterials. Congratulations Sam!

Saleh Group has published a journal article in Applied Biochemistry and Biotechnology titled, "Effect of Gold Nanosphere Surface Chemistry on Protein Adsorption and Cell Uptake in Vitro". 3rd year graduate student ARM Nabiul Afrooz and Dr. Saleh are co-authors in this paper with the nanotoxicology research group at Wright Patterson Air Force Base.

Saleh Group has recently received a competitive internal grant from the USC's VP of Research, Dr. Nagarkatii's office, under ASPIRE-I program. The title of the proposals is: "Heteroaggregation and deposition of chirally separated single-walled carbon nanotubes in heterogeneous aquatic systems". This project will deal with development of novel techniques for analyzing fate and transport of nanomaterials in complex natural systems.

A journal article entitled "Ultrasonication Study for Suspending Single-Walled Carbon Nanotubes in Water" has recently been accepted for publication in the Journal of Nanoscience and Nanotechnology where Dr. Saleh and Iftheker Khan are co-authors. This paper focuses on development of ultrasonication based standardized protocol for single walled carbon nanotube dispersion.

Iftheker Khan, a fourth year PhD student in Saleh Group has received 2nd prize in poster presentation on the Graduate Student Day 2012 at the University of South Carolina. The topic of his poster was 'Fractal Structures of Single-Walled Carbon Nanotubes in Environmental and Biologically Relevant Conditions: Role of Chirality.' Congratulations Iftheker!

A journal article entitled "Does Shape Matter? Bioeffects of Gold Nanomaterials in a Human Skin Cell Model" has recently been published in Langmuir where Dr. Saleh and Nabiul Afrooz are co-authors. This paper focuses on the shape dependent cellular response to gold nanoparticles.

A recent journal article from Saleh group titled "Preparation and Characterization of Stable Aqueous Higher Order Fullerenes" has been accepted in Nanotechnology. 2nd year graduate student Nirupam Aich is the lead author of this paper. The paper discussed aqueous solubilization of higher fullerenes and presents their interaction energies at molecular level and physicochemical properties. This paper has been highlighted by the journal as an 'article of particular interest'.

Saleh Group has recently received the Magellan Scholar Program grant from the University of South Carolina titled "MGS Modular Nano-Enabled Sorption Cartridge Design for Water Treatment". This grant will also help Sam Rollings, an undergraduate student from this group to perform innovative research as a prestigious Magellan scholar to remediate water pollution issues. Potential application of carbonaceous nanoparticles to perform in advanced water treatmet processes will be the focus of this research.

Saleh Group has presented two posters at the first Gordon Research Conference on Environmental Nanotechnology. The posters were titled as: "Aggregation Kinetics and Fractal Structures of Chirally Separated Single-Walled Carbon Nanotubes in Environmental and Biologically Relevant Systems" and "Removal of Micropollutants from Landfill Leachate, Seawater, and Brackish Water Using Single-Walled Carbon Nanotubes". These studies were funded by NSF and GSEC, respectively.

Dr. Saleh has recently presented an invited lecture at Wright Patterson Air Force Base (WPAFB), Dayton, OH. Dr. Saleh's talk titled, "Aggregation and Surface Interaction of Carbonaceous and Metallic Nanomaterials: Environmental and Biologically Relevant Conditions". Saleh Lab has established a successful collaboration with WPAFB and will continue to work closely with the scientists there in nano-toxicological studies.

In the most recent ACS National Meeting held at Anaheim, CA from March 27-31, 2011, three members from Saleh Group, ARM Nabiul Afrooz, Nirupam Aich, and Iftheker A. Khan, presented five papers in the area of environmental fate, transport, and effects of engineered nanomaterials. These papers were presented in the environmental chemistry division that included topics of aggregation kinetics and aggregate structure studies of chiral single-walled carbon nanotubes (Khan et al.) aggregation behaviour of higher fullerenes and hybrid nanomaterials (Aich and Saleh), and aggregation kinetics of rod-like gold nanomaterials(Afrooz et al).

Saleh Group has recently received a US Air Force (USAF) grant from the Wright Patterson Air Force Base titled, "Developing Predicting Capability for Nanoparticle Aggregation and Aggregate Structure Evolution in Biologically Relevant Systems". The project will focus on mechanistic understanding of nano-toxicity of metallic nanoparticles. This project is a result of a successful collaboration between Dr. Saleh and an eminent toxicologist and scientist Dr. Saber Hussain of USAF.

Saleh Group has published three journal papers in Toxicology and Applied Pharmacology, Reprod Toxicol and Water Res titled, "The effects of TiO2 and Ag nanoparticles on reproduction and development of Drosophila melanogaster and CD-1", "Investigating the effects of functionalized carbon nanotubes on reproduction and development in Drosophila melanogaster and CD-1 mice", and "Removal of bisphenol A and 17a-ethinyl estradiol from landfill leachate using single-walled carbon nanotubes", respectively. 2nd year graduate student ARM Nabiul Afrooz, 3rd year graduate student Iftheker A Khan, and Dr. Saleh are co-authors in these papers. The toxicology papers are a result of successful collaboration between the Saleh Group at USC and the Walker Group of Queens University, Canada. The third paper is published as an outcome of Dr. Saleh's research work on SWNT membranes with Dr. Yoon of USC.

Iftheker A Khan, a 3rd year PhD student in the Saleh Group has been awarded the prestigious American Chemical Society (ACS) Environmental Chemistry Graduate Student Award 2011. Iftheker competed nationally with the top environmental engineering graduate students to win this award. Award was based upon students' records in course work, evidence of research productivity and recommendations from graduate faculty advisor. Primary emphasis is given to Iftheker's potential for future contributions as professionals in environmental chemistry. The number of applications from qualified recipients exceeded previous years, which makes this award for 2011 highly competitive. Iftheker will receive a check from ACS Environmental Chemistry Division and Iftheker's, his Institution's, and advisor’s names will be posted on the ACS website for one full year. Congratulations Iftheker!

Dr. Saleh is co-organizing an Environmental Chemistry (ENVR) conference session at the 243rd ACS National Meeting-San Diego next March with Drs. John Fortner (University of Washington-St. Louis) and Saber Hussain (Wright Patterson Airforce Base and Wright State University). The title of session is "Nanomaterial Interaction on Biological Interfaces". All the organizers encourage authors to submit abstracts to this session. The abstract submission to PACS is now open thru October 17, 2011.

Nirupam Aich, a second year PhD student in the Saleh Group has been awarded the M. Bert Storey Endowed Graduate Fellowship, 2011-2012. This fellowship is awarded by Civil and Engineering Department of the College of Engineering and Computing in USC to the top Civil and Environmental graduate student. The fellowship is named after Mr. Bert Storey, a long time patron of the University. Nirupam will receive a $1,250 award as acknowledgement of his outstanding performance in study and research. Congratulations Nirupam! Iftheker A. Khan, another senior PhD student in the Saleh Group was awarded the same fellowship last year.