Toxicity and cellular uptake of gold nanoparticles: what we have learned so far?

Gold nanoparticles have attracted enormous scientific and technological interest due to their ease of synthesis, chemical stability, and unique optical properties. Proof-of-concept studies demonstrate their biomedical applications in chemical sensing, biological imaging, drug delivery, and cancer treatment. Knowledge about their potential toxicity and health impact is essential before these nanomaterials can be used in real clinical settings. Furthermore, the underlying interactions of these nanomaterials with physiological fluids is a key feature of understanding their biological impact, and these interactions can perhaps be exploited to mitigate unwanted toxic effects. In this Perspective we discuss recent results that address the toxicity of gold nanoparticles both in vitro and in vivo, and we provide some experimental recommendations for future research at the interface of nanotechnology and biological systems

Surface characterization of functionalized latexes with different surface functionalities using rheometry and dynamic light scattering

a b s t r a c t Here we study the formation of sterically stabilizing ''hairy" surface layers for a series of styrene-butylacrylate and styrene-butadiene latexes copolymerized either with acrylic acid (AA), methacrylic acid (MAA), itaconic acid (IA) or acrylamide (AM) using dynamic light scattering, steady shear and high frequency rheology. This phenomenon is investigated under different conditions of pH, ionic strength, and temperature. The AA copolymerized latex has the most extended hairy layer and is very sensitive to pH and ionic strength. MAA yields a thinner hairy layer than AA due to higher hydrophobicity. IA exhibits a hairy layer thickness of about 1 nm, since it terminates polymer chain growth. For the AM copolymerized latexes high frequency viscosity reveals the existence of a thin hairy layer and the high values of the low shear viscosity and the high frequency modulus are attributed to a weak, reversible flocculation. No significant effect of particle core composition or temperature on the formation of the hairy layer was observed. High frequency rheology is most valuable for characterization of surface layers of carboxylated latexes, since it provides not only direct information about the effective volume fraction but also characterizes the strength of colloidal interactions among particles and it is applied at high particle concentration relevant during manufacturing and processing