Atomic force microscopy in a liquid and in situ ellipsometry as complementary techniques for the study of protein adsorption

Abstract

The combination of two in situ techniques for the study of immobilization of biomolecules is seldom performed. Therefore, the combination of in situ ellipsometry with atomic force microscopy (AFM) in a liquid was used to follow the adsorption process of enolase, an enzyme of the glycolytic pathway. The adsorbed amount and topographic information of the adsorbed layers were obtained in the liquid environment. AFM images showed that surfaces with comparable adsorbed amounts of protein presented immobilized entities arranged in strings or in spherical clumps, evidencing the importance of combining in situ ellipsometry and AFM in a liquid.

Acknowledgements: The authors acknowledge FAPESP (grants 97/13070-2 and 00/08051-3) and CNPq for financial support, Sabrina M. Pancera (IQ/USP) and Rosangela Itri (IF/USP) for the small-angle X-ray scattering measurements and discussion of the results, and the National Laboratory of Synchrotron Light for the use of their facilities (SAS no. 1247/2).