Here we present in situ observations of adsorption of bovine serum albumin (BSA) on citrate-stabilized gold nanospheres. We implemented scattering correlation spectroscopy as a tool to quantify changes in the nanoparticle Brownian motion resulting from BSA adsorption onto the nanoparticle surface. Protein binding was observed as an increase in the nanoparticle hydrodynamic radius. Our results indicate the formation of a protein monolayer at similar albumin concentrations as those found in human blood. Additionally, by monitoring the frequency and intensity of individual scattering events caused by single gold nanoparticles passing the observation volume, we found that BSA did not induce colloidal aggregation, a relevant result from the toxicological viewpoint. Moreover, to elucidate the thermodynamics of the gold nanoparticle-BSA association, we measured an adsorption isotherm which was best described by an anti-cooperative binding model. The number of binding sites based on this model was consistent with a BSA monolayer in its native state. In contrast, experiments using poly-ethylene glycol capped gold nanoparticles revealed no evidence for adsorption of BSA.

Chromium nitride films were deposited on glass substrates using reactive dc planar magnetron sputtering. Film stress-state evaluation permitted a two-level classification into compressive and transition categories. Maximum stress levels in these compressive category films were in the (−) 0.83 to (−) 14.4 GPa range. Sputtering parameter weighting equations indicated the deposition parameters which influenced stress were sputtering pressure, sputtered flux incidence angle, film thickness, and the interactions between these parameters. Subsequent studies indicated substrate bias to be important in the −50 to −250 V interval. Thermal stresses contributed a compressive component of (−) 0.7 GPa which was approximately 4% of the peak compressive stress. Generally, deposition conditions promoting high normalized energies (energetic particle bombardment of the film) produced hard coatings which were highly stressed (compressive) with low resistivities.

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