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.Full Paper
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.Full Paper
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.
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!
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.