AFM Studies of Protein Adsorption: 1. Time-Resolved Protein Adsorption to Highly Oriented Pyrolytic Graphite
✍ Scribed by David C. Cullen; Christopher R. Lowe
- Publisher
- Elsevier Science
- Year
- 1994
- Tongue
- English
- Weight
- 621 KB
- Volume
- 166
- Category
- Article
- ISSN
- 0021-9797
No coin nor oath required. For personal study only.
✦ Synopsis
The adsorption of two proteins, immunoglobulin (\mathrm{G}) (IgG) and glucose oxidase (GOx), to a highly oriented pyrolytic graphite (11OP(i) surface has been studied in an aqueous environment using an atomic force microscone (AFM). The modes of adsorption of the two proteins were strikingly different when observed with scan dimensions of (\sim 5 \times 5 \mu \mathrm{m}) and at bulk protein concentrations of (50 \mu \mathrm{g} \cdot \mathrm{ml}^{-1}). IgG adsorption appeared to display nucleation at a number of sites that promoted the local binding of further (\mathrm{IgG}) molecules and resulted in a homogeneous distribution of adsorbed protein after prolonged times. In contrast, the time course for GOx adsorption foilowed a sparser distribution of initial nucleation sites, possibly at HOPG surface step defects, that promoted the rapid local adsorption of further protein and resulted eventually in a heterogeneous distribution comprising large sheets of adsorbed protein together with regions of bare HOPG. Simple interpretation of the apparent thicknesses of the adsorbed films measured with the AFM would suggest that (\operatorname{lgG}) adsorbed in a native conformation while GOx denatured during the adsorption process. In addition, lateral force microscopy of GOx adsorbed on HOPG further supported the interpretation of the topographic image data. 1994 Academic Press. Inc.