A Survey of the Levels of Selected Metals in U.S. Meat, Poultry, and Siluriformes Fish Samples Taken at Slaughter and Retail, 2017-2022.

The U.S. Department of Agriculture (USDA) Food Safety and Inspection Service (FSIS) conducts surveillance of metallic elements in U.

Novel analytical methods to assess the chemical and physical properties of liposomes.

Liposomes are used in commercial pharmaceutical formulations (PFs) and dietary supplements (DSs) as a carrier vehicle to protect the active ingredient from degradation and to increase the half-life of the injectable. Even as the commercialization of liposomal products has rapidly increased, characterization methodologies to evaluate physical and chemical properties of the liposomal products have not been well-established. Herein we develop rapid methodologies to evaluate chemical and selected physical properties of liposomal formulations.

Detection and characterization of SiO2 and TiO2 nanostructures in dietary supplements.

Nanomaterials are beginning to enter our daily lives through various consumer products as the result of technology commercialization. The development of methodologies to detect the presence of nanomaterials in consumer products is an essential element in understanding our exposure. In this study, we have developed methods for the separation and characterization of silicon dioxide (SiO2) and titanium dioxide (TiO2) nanostructures in dietary supplements marketed in products specifically targeted for women.

Simple functionalization strategies for enhancing nanoparticle separation and recovery with asymmetric flow field flow fractionation.

Due to the increasing use of engineered nanomaterials in consumer products, regulatory agencies and other research organizations have determined that the development of robust, reliable, and accurate methodologies to characterize nanoparticles in complex matrices is a top priority. Of particular interest are methods that can separate and determine the size of nanomaterials in samples that contain polydisperse and/or multimodal nanoparticle populations. Asymmetric-flow field flow fractionation (AF4) has shown promise for the separation of nanoparticles with wide size range distributions; however, low analyte recoveries and decreased membrane lifetimes, due to membrane fouling, have limited its application.

Adsorption of cellular proteins to polyelectrolyte-functionalized gold nanorods: a mechanism for nanoparticle regulation of cell phenotype?

Cell behavior in the presence of nanomaterials is typically explored through simple viability assays, but there is mounting evidence that nanomaterials can have more subtle effects on a variety of cellular functions. Previously our lab demonstrated that gold nanorods functionalized with polyelectrolyte multi-layers inhibited rat cardiac fibroblast-mediated remodeling of type I collagen scaffolds by altering fibroblast phenotype and the mechanical properties of the collagen network. In this work, we examine a possible mechanism for these effects: adsorption of cellular proteins by the nanorods.

Surface charge controls the fate of Au nanorods in saline estuaries.

This work reports the distribution of negatively charged, gold core nanoparticles in a model marine estuary as a function of time. A single dose of purified polystyrene sulfonate (PSS)-coated gold nanorods was added to a series of three replicate estuarine mesocosms to emulate an abrupt nanoparticle release event to a tidal creek of a Spartina -dominated estuary. The mesocosms contained several phases that were monitored: seawater, natural sediments, mature cordgrass, juvenile northern quahog clam, mud snails, and grass shrimp.

High-aspect-ratio gold nanorods: their synthesis and application to image cell-induced strain fields in collagen films.

Gold nanoparticles are receiving considerable attention due to their novel properties and the potential variety of their uses. Long gold nanorods with dimensions of approximately 20 × 400 nm exhibit strong light scattering and can be easily observed under dark-field microscopy. Here we describe the use of this light-scattering property to track micrometer scale strains in collagen gels and thick films, which result from cell traction forces applied by neonatal heart fibroblasts.

Shining light on nuclear-targeted therapy using gold nanostar constructs.

Nuclear-targeted therapy has received increasing attention as a potential strategy to improve the therapeutic efficacy of treating cancer. The main challenges include targeting, drug-delivery efficiency and release of anticancer agents to the cancer cell nucleus. Nanoparticles as nanocarriers have started to address some of these issues.

Direct observation of nanoparticle-cancer cell nucleus interactions.

We report the direct visualization of interactions between drug-loaded nanoparticles and the cancer cell nucleus. Nanoconstructs composed of nucleolin-specific aptamers and gold nanostars were actively transported to the nucleus and induced major changes to the nuclear phenotype via nuclear envelope invaginations near the site of the construct. The number of local deformations could be increased by ultrafast, light-triggered release of the aptamers from the surface of the gold nanostars.

Gold nanorods: their potential for photothermal therapeutics and drug delivery, tempered by the complexity of their biological interactions.

Gold nanorods have promising applications in the fields of drug delivery and photothermal therapy. These promises arise from the nanorods' unique optical and photothermal properties, the availability of synthetic protocols that can tune the size and shape of the particles, the ability to modify the surface and conjugate drugs/molecules to the nanorods, and the relative biocompatibility of gold nanorods. In this review, current progress in using gold nanorods as phototherapeutic agents and as drug delivery vehicles is summarized.

Polyelectrolyte-coated gold nanorods and their interactions with type I collagen.

Gold nanorods (AuNRs) have unique optical properties for numerous biomedical applications, but the interactions between AuNRs and proteins, particularly those of the extracellular matrix (ECM), are poorly understood. Here the effects of AuNRs on the self-assembly, mechanics, and remodeling of type I collagen gels were examined in vitro. AuNRs were modified with polyelectrolyte multilayers (PEMs) to minimize cytotoxicity, and AuNRs with different terminal polymer chemistries were examined for their interactions with collagen by turbidity assays, rheological tests, and microscopy.

Transfer of gold nanoparticles from the water column to the estuarine food web.

Within the next five years the manufacture of large quantities of nanomaterials may lead to unintended contamination of terrestrial and aquatic ecosystems. The unique physical, chemical and electronic properties of nanomaterials allow new modes of interaction with environmental systems that can have unexpected impacts. Here, we show that gold nanorods can readily pass from the water column to the marine food web in three laboratory-constructed estuarine mesocosms containing sea water, sediment, sea grass, microbes, biofilms, snails, clams, shrimp and fish.

Surface-coverage dependence of surface-enhanced raman scattering from gold nanocubes on self-assembled monolayers of analyte.

Surface enhanced Raman scattering (SERS) spectra of 4-mercaptobenzoic acid (4-MBA) self-assembled monolayers (SAMs) on gold substrates are presented for SAMs onto which gold nanocubes have been electrostaticaly immobilized. In the absence of nanocubes, no SERS signals from 4-MBA SAMs are observed. Upon addition of the gold nanocubes to the SAM, a sandwich architecture is formed, allowing for coupling between the localized surface plasmon of the nanocubes and the surface plasmon of the gold substrate.

The effect of gold nanorods on cell-mediated collagen remodeling.

Cardiac fibroblasts, the noncontractile cells of the heart, contribute to myocardial maintenance through the deposition, degradation, and organization of collagen. Adding polyelectrolyte-coated gold nanorods to three-dimensional constructs composed of collagen and cardiac fibroblasts reduced contraction and altered the expression of mRNAs encoding beta-actin, alpha-smooth muscle actin, and collagen type I. These data show that nanomaterials can modulate cell-mediated matrix remodeling and suggest that the targeted delivery of nanomaterials can be applied for antifibrotic therapies.

Gold nanoparticles in biology: beyond toxicity to cellular imaging.

Gold, enigmatically represented by the target-like design of its ancient alchemical symbol, has been considered a mystical material of great value for centuries. Nanoscale particles of gold now command a great deal of attention for biomedical applications. Depending on their size, shape, degree of aggregation, and local environment, gold nanoparticles can appear red, blue, or other colors.

Chemical sensing and imaging with metallic nanorods.

In this Feature Article, we examine recent advances in chemical analyte detection and optical imaging applications using gold and silver nanoparticles, with a primary focus on our own work. Noble metal nanoparticles have exciting physical and chemical properties that are entirely different from the bulk. For chemical sensing and imaging, the optical properties of metallic nanoparticles provide a wide range of opportunities, all of which ultimately arise from the collective oscillations of conduction band electrons ("plasmons") in response to external electromagnetic radiation.

Using gold nanorods to probe cell-induced collagen deformation.

In biological tissue, complex mechanisms of cellular response are closely linked to the mechanical environment that cells experience. The key to understanding these mechanisms may lie in measurement of local mechanical fields near living cells and between cells. We have developed a novel optical measurement technique which combines the light elastically scattered from gold nanorods with digital image analysis to track local deformations that occur in vitro between cells, in real time, under darkfield optical microscopy.