ζ-potential characterization of collagen and bovine serum albumin modified silica nanoparticles: a comparative study
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In this study, bovine serum albumin (BSA) and collagen (COLL) were adsorbed independent of one another, onto the surface of silica nanoparticles (SNPs) at pH’s where the ζ-potential of the proteins were equal in magnitude, but opposite to the SNP surface to ascertain the differences in surface coverage and conformation in the adsorbed layer. In both systems, increasing the concentration of free protein resulted in an increase in protein surface coverage and ζ values, with ζ values approaching that of native protein at high surface coverage. However, a lower critical charge reversal concentration range was measured for COLL relative to BSA (COLL: 0–25 μg/mL, BSA: 25–90 μg/mL). Additionally, a considerable difference in ζ for adsorbed protein versus free protein was observed. These results when interpreted in terms of the theory of Ottewill and Watanabe indicate a higher Gibbs energy of association for COLL versus BSA on SNP surfaces, accompanied by perturbation in protein structure.
KeywordsSilica Nanoparticles Adsorbed Protein Free Molecule Free Protein Coated Particle
This work was supported in part by a GANN fellowship to WJZ, a research grant from the Nanotechnology Institute (NTI) via Ben Franklin Technology Partners of Northeast Pennsylvania to VPS and IWC and the Vanderbilt Institute of Chemical Biology (VICB). The authors thank Ashwath Jayagopal for help with the confocal images of the protein-coated SNP and Dr. Christopher Pino for helpful suggestions.
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