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.


Abstract:

Gold nanoparticles exhibit unique spectral properties that make them ideal for biosensing, imaging, drug delivery, and other therapeutic applications. Interaction of gold nanoparticles within biological environments is dependent on surface characteristics, which may rely on particular capping agents. In this study, gold nanospheres (GNS) synthesized with different capping agents-specifically citric acid (CA) and tannic acid (TA)- were compared for serum protein adsorption and cellular uptake into a lung epithelial cell-line (A549). Both GNS samples exhibited noticeable protein adsorption based on surface charge data after exposure to serum proteins. Light scattering measurements revealed that GNS-CA-protein composites were smaller and less dense compared to GNS-TA-protein composites. The cell uptake characteristics of these NPs were also different. GNS-CA formed large clusters and elicited high uptake, while GNS-TA were taken up as discrete particles, possibly through non-endosomal mechanisms. These results indicate that the capping agents used for GNS synthesis result in unique biological interactions.

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. .

Abstract:

A systematic calorimetry-based technique was developed to standardize single-walled carbon nanotube (SWNT) dispersion protocol. Simple calorimetric experiments were performed to benchmark the performance of the ultra-dismembrator. Temperature profiles for the sonication period were utilized to estimate energy input to the system. Energy loss profile was generated for the ultra-dismembrator in use and a calibration relationship was formulated that could standardize the sonication process. The standardized protocol was used to prepare aqueous SWNT suspensions-sonicating SWNTs in a varied range of input energy (18-100 kJ) in water. SWNT mass fractions suspended for each energy input was accurately measured and the suspended SWNT samples were characterized for morphology, surface potential, cluster size and structure, and chemical functionality using high resolution transmission electron microscopy (HRTEM), electrophoresis, dynamic and static light scattering (DLS/SLS), and Raman spectroscopy. The study demonstrated that suspended mass of SWNTs increased up to 18 kJ of energy input with no further increase upon continued energy input. The physicochemical properties showed similar trend for energy input. The aggregate cluster size, surface potential behavior, as well as the Raman defect properties plateaued after the initial energy input. The significant changes observed were limited to morphological properties, i.e., shorter length, debundled, and sharp edged SWNTs and fractal cluster formation (lower Df) with increased input energy.

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.

Abstract:

Gold nanomaterials (AuNMs) have distinctive electronic and optical properties, making them ideal candidates for biological, medical, and defense applications. Therefore, it is imperative to evaluate the potential biological impact of AuNMs before employing them in any application. This study investigates two AuNMs with different aspect ratios (AR) on mediation of biological responses in the human keratinocyte cell line (HaCaT) to model potential skin exposure to these AuNMs. The cellular responses were evaluated by cell viability, reactive oxygen species (ROS) generation, alteration in gene and protein expression, and inflammatory response. Gold nanospheres, nominally 20 nm in diameter and coated with mercaptopropane sulfonate (AuNS-MPS), formed agglomerates when dispersed in cell culture media, had a large fractal dimension (Df = 2.57+-0.4) (i.e., tightly bound and densely packed) and were found to be nontoxic even at the highest dose of 100 ?g/mL. Highly uniform, 16.7 nm diameter, and 43.8 nm long polyethylene glycol-capped gold nanorods (AuNR-PEG) also formed agglomerates when dispersed into the cell culture media. However, the agglomerates had a smaller fractal dimension (Df = 1.28+-0.08) (i.e., loosely bound) and were found to be cytotoxic to the HaCaT cells, with a significant decrease in cell viability occurring at 25 microgram/mL and higher. Moreover, AuNR-PEG caused significant ROS production and up-regulated several genes involved in cellular stress and toxicity. These results, combined with increased levels of inflammatory and apoptotic proteins, demonstrated that the AuNR-PEG induced apoptosis. Exposure to AuNS-MPS, however, did not show any of the detrimental effects observed from the AuNR-PEG. Therefore, we conclude that shape appears to play a key role in mediating the cellular response to AuNMs.

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'.
Full Paper

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 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.

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.

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.

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.

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.

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).

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.

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!

Saleh Group has published a recent paper in J Haz Mat. titled, "Barrier properties of poly(vinyl alcohol) membranes containing carbon nanotubes or activated carbon". 3rd year graduate student Iftheker A Khan, former undergrad researcher Atif A Chowdhury, and Dr. Saleh are co-authors in this paper with University of Minnesota’s Bill Arnold. This paper focuses on improvement of PVA membrane properties through incorporation of carbon nanotubes for removal of dissolved tri-chlorobenzene and copper.

Abstract
Carbon nanotube addition has been shown to improve the mechanical properties of some polymers. Because of their unique adsorptive properties, carbon nanotubes may also improve the barrier performance of polymers used in contaminant containment. This study compares the barrier performance of poly(vinyl alcohol) (PVA) membranes containing single-walled carbon nanotubes (SWCNTs) to that for PVA containing powdered activated carbon (PAC). Raw and surface-functionalized versions of each sorbent were tested for their abilities to adsorb 1,2,4-trichlorobenzene and Cu2+, representing the important hydrophobic organic and heavy metal contaminant classes, as they diffused across the PVA. In both cases, PAC (for 1,2,4-trichlorobenzene) and functionalized PAC (for Cu2+) outperformed SWCNTs on a per mass basis by trapping more of the contaminants within the barrier membrane. Kinetics of sorption are important in evaluating barrier properties, and poor performance of SWCNT-containing membranes as 1,2,4-TCB barriers is attributed to kinetic limitations.

Iftheker A khan, a second year PhD student in the Saleh Group has been awarded the M. Bert Storey Endowed Graduate Fellowship, 2010-2011. 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. Iftheker will receive a $1,250 award that will support his research activities. Congratulations Iftheker!

USC Nanocenter has selected Dr. Saleh as the nano-environmental thrust leader. He is the only untenured Assistant Professor among seven other distinguished Professors in this elite pack of leaders of nanotechnology thrusts. Dr. Saleh's primary role will be to frame USC's nano-environmental research focus in the coming years under the guidance of the Nanocenter Director Tom Vogt.

USC Nanocenter has profiled Saleh Group's recent grant on nanoeducation in the amount of $200,000, funded by the EEC directorate of the National Science Foundation. The project is titled "NUE: Nano in a Global Context for Engineering Students". Read more on this grant in the Nanocenter website.

Saleh Group has received a grant on nanoeducation in the amount of $200,000, funded by the EEC directorate of the National Science Foundation. The project is titled "NUE: Nano in a Global Context for Engineering Students". Read more on this grant in the Civil and Environmental Engineering department website.

Dr. Saleh has been selected as the only outside Virginia Tech faculty to take part in the multi-disciplinary sustainable nanotechnology effort of Virginia Tech Center of Sustainable Nanotechnology (VTSuN) center. The mission of VTSuN is to conduct and publicly disseminate research results concerning the development and evaluation of promising green nanomaterials, nanodevices, and nanotechnologies for their environmental sustainability and safety as well as the application of nanotechnology and nanoscience to environmental sustainability issues. Professor Saleh will be collaborating with the center to understand the environmental transport of nanomaterials in river systems, an area that has remained virtually unexplored. VTSuN's team i.e., Drs. Navid Saleh, Panos Diplas, Clint Dancey, and Michael Hochella, is preparing a number of proposals to be submitted to NSF, NIH, and other funding agencies.

In the most recent ACS National Meeting held at Boston, MA from August 22-26, 2010, three members from Saleh Group, ARM Nabiul Afrooz, Nirupam Aich, and Iftheker A. Khan, presented four 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 behavior of chiral single-walled carbon nanotubes and hybrid nanomaterials (Khan et al. and Aich and Saleh), deposition behavior of anisotroic gold nanomaterials (Afrooz et al), and antimicrobial effect of anisotropic gold nanomaterials (Afrooz et al).

Proceeding Details:

Afrooz, A. R. M. N., Aich, N., Khan, I. A., Saleh, N. B. "Deposition Behavior of Anisotropic Nanomaterials", ACS National Meeting, Aug 22-26, 2010, Boston, MA.

Khan, I. A., Ferguson, P. L., Sabo-Attwood, T., Saleh, N. B. "Systematic Change in Chirality Affects Aggregation Kinetics of Single-Walled Carbon Nanotubes", ACS National Meeting, Aug 22-26, 2010, Boston, MA.

Aich, N., Saleh, N. B. "Aggregation Kinetics of Fullerene-Single-walled Carbon Nanotube Hybrids", ACS National Meeting, Aug 22-26, 2010, Boston, MA.

Afrooz, A. R. M. N., Zaib, Q., Decho, A. W., Saleh, N. B. "Role of Nanoparticle Geometry on Nano-bio Interaction: A Quest to Separate Physics from Chemistry", ACS National Meeting, Aug 22-26, 2010, Boston, MA.

Dr. Tara Sabo-Attwood of Environmental Health Science Department of Arnold School of Public Health at the University of South Carolina has presented a research paper on immunomodulatory response of engineered nanomaterials at the Nano 2010 conference. This international conference was jointly organized by SETAC and Clemson University that was held from August 22-26, 2010 at Clemson, SC. Saleh Group works in close collaboration with Dr. Sabo-Attwood to decipher the mechanistic interaction of engineered nanoparticles with eukaryotic cells.

Proceeding Details:

Sabo-Attwood, T., Brusch-Richardson, L., Ariza, M. E., Khan, I. A., Saleh, N. B., "Assessment of Immunomodulatory Potential of Engineered Nanoparticles" Environmental Effects of Nanoparticles and Nanomaterials, SETAC-Clemson University, Aug 22-26, 2010, Clemson, SC.

A journal article entitled "Multiwalled Carbon Nanotube Filter: Improving Viral Removal at Low Pressure" has recently been published in Langmuir where Dr. Saleh is a co-author. This paper focuses on the possibilities of cost-effective efficient virus removal processes using multiwalled carbon nanotubes filters.

Abstract:

The effective removal of viruses by a multiwalled carbon nanotube (MWNT) filter is demonstrated over a range of solution chemistries. MS2 bacteriophage viral removal by the MWNT filter was between 1.5 and 3 log higher than that observed with a recently reported single-walled carbon nanotube (SWNT) filter when examined under similar loadings (0.3 mg/cm2) of carbon nanotubes (CNTs). The greater removal of viruses by the MWNT filter is attributed to a more uniform CNT-filter matrix that allows effective removal of viruses by physicochemical (depth) filtration. Viral removal by the MWNT filter was examined under a broad range of water compositions (ionic strength, monovalent and divalent salts, solution pH, natural organic matter, alginate, phosphate, and bicarbonate) and filter approach velocities (0.0016, 0.0044, and 0.0072 cm/s). Log viral removal increased as the fluid approach velocity decreased, exhibiting a dependence on approach velocity in agreement with colloid filtration theory for Brownian particles. Viral removal improved with increasing ionic strength (NaCl), from 5.06 log removal at 1 mM NaCl to greater than 6.56 log removal at 100 mM NaCl. Addition of calcium ions also enhanced viral removal, but the presence of magnesium ions resulted in a decrease in viral removal. Solution pH also played an important role in viral removal, with log removals of 8.13, 5.38, and 4.00 being documented at solution pH values of 3.0, 5.5, and 9.0, respectively. Dissolved natural organic matter (NOM) had a negligible effect on viral removal at low concentration (1 mg/L), but higher concentrations of NOM significantly reduced the viral removal by the MWNT filter, likely due to steric repulsion. Addition of alginate (model polysaccharide) also caused a marked decrease in viral removal by the MWNT filter. This highly scalable MWNT-filter technology at gravity-driven pressures presents new, cost-effective options for point-of-use filters for viral removal.

Dr. Saleh presented a technical lecture titled "Applications and Implications of Nanotechnology". The seminar, held ITN Centre at Civil Bldg (BUET), was open for the faculties and students. In his speech Dr. Saleh addressed how the nanotechnology and nanomaterials can be applied to solve environmental and health problems. The seminar was followed by a lively discussion session with audience. Read More

As a lead researcher in the study of the environmental impact of the carbon based nanomaterials Dr. Saleh was invited to present in the international conference on carbon nano- and macro-scale materials held at Clemson University, Clemson, SC from July 11-16, 2010. Dr. Saleh presented experimental and theoretical insight into the fundamental aggregation and deposition behavior of carbon nanotubes in aquatic environment.

Proceeding Details:

Saleh, N. "Aggregation and Deposition Behavior of Carbon Nanotubes in Aquatic Environments" Clemson Carbon Conference, July 11-16, 2010, Clemson, SC.

Marquis Who's Who has nominated Dr. Saleh for Who's Who in Science and Engineering 2011-2012. Marquis Who's Who is the premiere biographer for American leaders in academia and industry since 1899. This honor is awarded to listees with significant contribution to their respective fields.

Saleh Group has been awarded a grant by USC Nanocenter to establish the first of its kind study of environmental fate and transport of hybrid nanomaterials. The project will be accomplished in joint collaboration with Dr. Harry Dorn in Virginia Tech. Read more on the project in our research page.

Saleh Group has been awarded a grant by Goldstar E&C, Korea, to study effect of carbon nanotubes in removing endocrine disrupting compounds from wastewater. Dr. Saleh, a Co-PI in the project, is a key contributor to the nanomaterial characterization, functionalization, and use. The project will be accomplished in joint collaboration with Drs. Yeomin Yoon (PI) and Joseph Flora (Co-PI) in USC. Read more on the project in our research page.

Leslyn Brusch-Richardson, a co-advised student of Drs. Navid Saleh and Tara Sabo-Attwood has presented a research paper on immunomodulatory response of engineered nanomaterials at the Society of Toxicology (SOT) Annual meeting held at Salt Lake City, UT from March 07-11, 2010. Saleh Group works in close collaboration with Dr. Sabo-Attwood to decipher the mechanistic interaction of engineered nanoparticles with eukaryotic cells.

Proceeding Details:

Brusch-Richardson, L., Ariza, M. E., Saleh, N. B., Sabo-Attwood, T. "Development of a High Throughput Assay to Assess the Immunomodulatory Potential of Engineered Nanoparticles" Society of Toxicology 49th Annual Meeting, March 07-11, 2010, Salt lake City, UT.

A journal article titled "Influence of Biomacromolecules and Humic Acid on Aggregation Kinetics of Single-Walled Carbon Nanotubes" has recently been published in Environmental Science & Technology that studies aggregation behavior of single-walled carbon nanotubes (SWNTs) in natural organic matter and biomacromolecules of biological and environmental relevance. The study chose humic acid, bovine serum albumin (BSA), Luria broth (LB), and alginate as the natural and biological macromolecules to study the aggregation kinetics of SWNTs.

Abstract

The initial aggregation kinetics of single-walled carbon nanotubes (SWNTs) were studied using time-resolved dynamic light scattering. Aggregation of SWNTs was evaluated in the presence of natural organic matter [Suwannee River humic acid (SRHA)], polysaccharide (alginate), protein [bovine serum albumin (BSA)], and cell culture medium [Luria-Bertani (LB) broth] with varying solution concentrations of monovalent (NaCl) and divalent (CaCl2) salts. Increasing salt concentration and adding divalent calcium ions induced SWNT aggregation by screening electrostatic charge and thereby suppressing electrostatic repulsion, similar to observations with aquatic colloidal particles. The presence of biomacromolecules significantly retarded the SWNT aggregation rate. BSA protein molecules were most effective in reducing the rate of aggregation followed by SRHA, LB, and alginate. The slowing of the SWNT aggregation rate in the presence of the biomacromolecules and SRHA can be attributed to steric repulsion originating from the adsorbed macromolecular layer. The remarkably enhanced SWNT stability in the presence of BSA, compared to that with the other biomacromolecules and SRHA, is ascribed to the BSA globular molecular structure that enhances steric repulsion. The results have direct implications for the fate and behavior of SWNTs in aquatic environments and biological media.

Saleh Group has received a grant in the amount of $400,000, funded by the CBET directorate of the National Science Foundation. The project is titled "Influence of diameter and chirality of single-walled carbon nanotubes on their fate and effects in the aquatic environment". Read more on this grant in our research page.

A journal article titled "Effect of Adsorbed Polyelectrolytes on Nanoscale Zero Valent Iron Particle Attachment to Soil Surface Models" has recently been published in Environmental Science & Technology which discusses the effect of coatings on the interaction of nanoscale zerovalent iron (NZVI) and soil surface. Dr. Saleh is a co-author in this paper.

Abstract

Polyelectrolyte coatings significantly increase the mobility of nanoscale zerovalent iron (NZVI) in saturated porous media. The effect can be attributed to improved colloidal stability of NZVI suspensions, decreased adhesion to soil surfaces, or a combination of the two effects. This research explicitly examines how coatings control NZVI adhesion to model soil surfaces. NZVI was coated with three different polyelectrolyte block copolymers based on poly(methacrylic acid), poly(methyl methacrylate or butyl methacrylate), and poly(styrenesulfonate) or with a poly(styrenesulfonate) homopolymer. SiO2 and a humic acid film served as model soil surfaces. The polyelectrolytes increased the magnitude of the electrophoretic mobility of NZVI over a broad pH range relative to unmodified NZVI and shifted the isoelectric point outside the typical groundwater pH range. Quartz crystal microgravimetry measurements indicated extensive adhesion of unmodified NZVI to SiO2. Polyelectrolyte coatings decreased adhesion by approximately 3 orders of magnitude. Adding 50 mM NaCl to screen electrostatic repulsions did not significantly increase adhesion of modified NZVI. Coated NZVI did not adhere to humic acid films for either 1 mM NaHCO3 or 1 mM NaHCO3 + 50 mM NaCl. The lack of adhesion even in a high ionic strength medium was attributed to electrosteric repulsion, as opposed to electrostatic double layer repulsion, between the polyelectrolyte-coated NZVI and the negatively charged surfaces. The lack of significant adhesion on either model surface was observed for all polymer architectures investigated.