A5008016664- Nanoparticles: synthesis and applications
- Gold and Silver Nanoparticles Synthesis and Applications
- Field-Flow Fractionation Techniques
- Nanoparticle-Based Drug Delivery
- Electrochemical Analysis and Applications
- Electrostatics and Colloid Interactions
- Water Quality Monitoring and Analysis
- Microplastics and Plastic Pollution
- Nanotechnology research and applications
- Ferroelectric and Piezoelectric Materials
- Graphene and Nanomaterials Applications
- Analytical chemistry methods development
- Dendrimers and Hyperbranched Polymers
- Concrete and Cement Materials Research
- Force Microscopy Techniques and Applications
- Iron oxide chemistry and applications
- Catalytic Processes in Materials Science
- Coagulation and Flocculation Studies
- Geophysical and Geoelectrical Methods
- Microfluidic and Bio-sensing Technologies
- Nanomaterials for catalytic reactions
- Polymer Surface Interaction Studies
- Analytical Chemistry and Sensors
- Heavy metals in environment
- Surfactants and Colloidal Systems
Material Measurement Laboratory
2015-2025
National Institute of Standards and Technology
2016-2025
National Institute of Standards
2001-2019
National Postdoctoral Association
2018
Materials Science & Engineering
2002-2004
American Ceramic Society
1997-2003
United States Department of Commerce
2002
Information Technology Laboratory
2002
Baker Engineering (United States)
2002
Virginia Transportation Research Council
2001
Studies designed to investigate the environmental or biological interactions of nanoscale materials frequently rely on use ultrasound (sonication) prepare test suspensions. However, inconsistent application ultrasonic treatment across laboratories, and lack process standardization can lead significant variability in suspension characteristics. At present, there is widespread recognition that sonication must be applied judiciously reported a consistent manner quantifiable reproducible;...
The adsorption and conformation of bovine serum albumin (BSA) on gold nanoparticles (AuNPs) were interrogated both qualitatively quantitatively via complementary physicochemical characterization methods. Dynamic light scattering (DLS), asymmetric-flow field flow fractionation (AFFF), fluorescence spectrometry, attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy combined to characterize BSA-AuNP conjugates under fluid conditions, while in the aerosol state...
Novel physicochemistries of engineered nanomaterials (ENMs) offer considerable commercial potential for new products and processes, but also the possibility unforeseen negative consequences upon ENM release into environment. Investigations ecotoxicity have revealed that unique properties ENMs a lack appropriate test methods can lead to results are inaccurate or not reproducible. The occurrence spurious misinterpretations from toxicity tests investigations (as opposed traditional toxicants)...
Suspensions of natural graphite particles were prepared in an aqueous medium using carboxymethyl cellulose (CMC) and emulsified styrene-butadiene copolymer latex as part environmentally friendly fabrication process for anodes (negative electrodes) intended application Li-ion batteries. characterized by adsorption isotherms, electroacoustic measurements, rheology sedimentation tests, at two different degrees substitution (DS) on CMC. A lower DS value (0.7) resulted greater uptake CMC compared...
The role of poly(acrylic acid) (PAA) in the dispersion silicon nitride suspensions was investigated experimentally. effects concentration, relative molecular mass, and suspension pH were evaluated. ionization PAA characterized by potentiometric titration indicated a pH‐dependent conformational transition. isoelectric point for decreased from 6.3 to 3 as concentration increased, roughly independent mass. A broadening stability region attributed this effect. Redispersion alkaline media,...
The reported size distribution of silver nanoparticles (AgNPs) is strongly affected by the underlying measurement method, agglomeration state, and dispersion conditions. A selection AgNP materials with vendor-reported diameters ranging from 1 nm to 100 nm, various distributions, biocompatible capping agents including citrate, starch polyvinylpyrrolidone were studied. AgNPs diluted either deionized water, moderately hard reconstituted or water containing natural organic matter. Rigorous...
Surface-sensitive quantitative studies of competitive molecular adsorption on nanoparticles were conducted using a modified attenuated total reflectance–Fourier transform infrared (ATR-FTIR) spectroscopy method. Adsorption isotherms for thiolated poly(ethylene glycol) (SH-PEG) gold (AuNPs) as function mass (1, 5, and 20 kDa) characterized. We find that surface density SH-PEG AuNPs is inversely proportional to the (Mm). Equilibrium binding constants SH-PEG, obtained Langmuir model, show...
We describe a comprehensive optimisation study culminating in standardised and validated approach for the preparation of titanium dioxide (TiO2) nanoparticle dispersions relevant biological media. This utilises TiO2 reference nanomaterial based on commercially available powder that has been widely examined both acute chronic toxicity studies. The dispersion as presented here satisfies four key harmonisation requirements not previously addressed: (1) method transferability, part use...
Little is understood regarding the impact that molecular coatings have on nanoparticle dissolution kinetics and agglomerate formation in a dilute dispersion. Dissolution agglomeration processes compete removing isolated nanoparticles from dispersion, making quantitative time-dependent measurements of mechanisms loss particularly challenging. In this article, we present situ ultra-small-angle X-ray scattering (USAXS) results, simultaneously quantifying dissolution, agglomeration, stability...
The increased use and incorporation of engineered nanoparticles (ENPs) in consumer products requires a robust assessment their potential environmental implications. However, lack standardized methods for nanotoxicity testing has yielded results that are sometimes contradictory. Standard ecotoxicity assays may work appropriately some ENPs with minimal modification but produce artifactual others. Therefore, understanding the robustness range is critical. In this study, we evaluated performance...
The impact and behavior of engineered nanomaterials (ENMs) entering the environment is an important issue due to their growing use in consumer agricultural products. Their mobility fate are heavily impacted by interactions with natural particle components saturated sediments soils. In this study, functionalized gold nanoparticles (AuNPs - used as model ENMs) were spiked into complex solid-containing media (standard soils estuarine sediment moderately hard water). AuNPs characterized...
Cerium oxide nanomaterials (nanoceria, CNMs) are receiving increased attention from the research community due to their unique chemical properties, most prominent of which is ability alternate between Ce3+ and Ce4+ oxidation states. While many analytical techniques methods have been employed characterize amounts present (Ce3+/Ce4+ ratio) within nanoceria materials, to-date no studies used multiple complementary tools (orthogonal analysis) with technique-independent state controls for...
Liposomal formulations for the treatment of cancer and other diseases are most common form nanotechnology enabled pharmaceuticals (NEPs) submitted market approval in clinical application today. The accurate characterization their physical-chemical properties is a key requirement; particular, size, size distribution, shape, stability among that regulators identify as critical quality attributes. Here we develop validate an optimized method, based on multi-detector asymmetrical-flow field flow...
The peak particle size and expanded uncertainties (95 % confidence interval) for two new calibration standards are measured as 101.8 nm ± 1.1 60.39 0.63 nm. samples polystyrene spheres suspended in filtered, deionized water at a mass fraction of about 0.5 %. distribution measurements aerosolized particles made using differential mobility analyzer (DMA) system calibrated SRM(®) 1963 (100.7 spheres). An electrospray aerosol generator was used generating the 60 to almost eliminate generation...
The chemical and electrostatic interactions at mineral−water interfaces are of fundamental importance in many geochemical, materials science, technological processes; however, the effects particle size nanoscale on these poorly known. Therefore, comprehensive experimental characterization studies were completed, to begin assess surface reactivity charging metal-oxide nanoparticles aqueous solutions. Commercially available crystalline anatase (TiO2) particles characterized using neutron X-ray...
Competitive adsorption kinetics between thiolated polyethylene glycol (SH-PEG) and mercaptopropionic acid (MPA) on gold nanoparticles (Au-NPs) were studied using a prototype physical characterization approach that combines dynamic light scattering (DLS) electrospray differential mobility analysis (ES-DMA). The change in hydrodynamic particle size (intensity average) due to the formation of SH-PEG coatings Au-NPs was measured by DLS both two-component (Au-NP + MPA or Au-NP SH-PEG)...