Interaction Of Silica Nanoparticles Research Articles

Protein stabilization through supramolecular host–guest interactions with cyclodextrin-modified nanoparticles

This study demonstrates the protein stabilization of gelatin through supramolecular interactions of silica nanoparticles and the influence on the point of denaturation. The phenomenon was studied in diluted solutions by dynamic light scattering, viscosity measurements, and differential scanning calorimetry. Native gelatin is stabilized by cyclodextrin functionalized SiO2 nanoparticles. After heating, increased supramolecular interactions of the nanoparticles with the denaturated gelatin coils are observed by progressive agglomeration. The described observation also resulted in a melting temperature shift from 30 °C, for native gelatin, to about 47 °C for the gelatin/CD-SiO2, which indicates the supramolecular stabilization of the gelatin chain structure. It was found that the gelatin is supramolecularly immobilized on the nanoparticle up to a certain temperature through complexation by cyclodextrin. The described results, also confirmed by DSC and viscosity measurements, show the prospect of using cyclodextrin-modified surfaces for the immobilization of the proteins.

Cellular uptake, evolution, and excretion of silica nanoparticles in human cells

A systematic study on the interaction of silica nanoparticles (NPs) with human cells has been carried out in the present work. Endocytosis and exocytosis are identified as major pathways for NPs entering, and exiting the cells, respectively. Most of the NPs are found to be enclosed in membrane bounded organelles, which are fairly stable (against rupture) as very few NPs are released into the cytoplasm. The nanoparticle-cell interaction is a dynamic process, and the amount of NPs inside the cells is affected by both the amount and morphology (degree of aggregation) of NPs in the medium. These interaction characteristics determine the low cytotoxicity of SiO(2) NPs at low feeding concentration.

Interactions of silica nanoparticles in supercritical carbon dioxide

We report molecular simulation studies on the interaction forces between silica nanoparticles in supercritical carbon dioxide at 318 K. Our goal is to find a better understanding of the interparticle solvation forces during rapid expansion of supercritical solutions. The parameters for interatomic potentials of fluid-fluid and solid-fluid interactions are obtained by fitting our simulations to (i) experimental bulk CO(2) phase diagram at a given temperature and pressure and (ii) CO(2) sorption isotherms on silica at normal boiling and critical temperatures. Our simulations show that the interaction forces between particles and supercritical CO(2) at near-critical pressure of p=69 atm (i.e., slightly below critical condition) reaches a minimum at distances of 0.5-0.8 nm between the outer surfaces of the particles and practically vanishes at distances of approximately 3 nm. The attraction is most prominent for densely hydroxylated particle surfaces that interact strongly with CO(2) via hydrogen bonds. The effective attraction between silica and CO(2) is significantly weaker for dehydroxylated particles. We also compared fluid sorption and interparticle forces between supercritical CO(2) and subcritical nitrogen vapor, and our results showed qualitative similarities, suggesting that the CO(2) configuration between the particles resembles a liquidlike junction.