Adsorption of bovine serum albumin on fused silica: Elucidation of protein-protein interactions by single-molecule fluorescence microscopy

K. M. Yeung, Z. J. Lu, Nai Ho CHEUNG*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

19 Citations (Scopus)

Abstract

The adsorption of bovine serum albumin (BSA) on fused silica at pH 4.7 was studied at the single molecules level by total-internal-reflection fluorescence microscopy. This pH value was the isoelectric point of BSA. At low [BSA] of 20 pM, protein molecules adsorbed as monomers. At intermediate [BSA] of 500 pM, protein molecules adsorbed as clusters of about five monomers on average. Both monomers and clusters had adsorption rate coefficients of the order 10-7 m s-1 and desorption rate coefficients of about 2 × 10-2 s-1. The respective steady-state coverage was about 10× higher than that at neutral pH, presumably because of the more favorable BSA-silica electrostatics. At pH 4.7 and with [BSA] higher than 100 nM, adsorption begot further adsorption to produce nonlinear isotherms. The coverage at 1 μM BSA was 2.5× that of the linearly extrapolated coverage. This suggests that at pH 4.7, solute-adsorbate affinity was the dominant factor that explains the enhanced adsorption observed in ensemble measurements.

Original languageEnglish
Pages (from-to)246-250
Number of pages5
JournalColloids and Surfaces B: Biointerfaces
Volume69
Issue number2
DOIs
Publication statusPublished - 1 Mar 2009

Scopus Subject Areas

  • Biotechnology
  • Surfaces and Interfaces
  • Physical and Theoretical Chemistry
  • Colloid and Surface Chemistry

User-Defined Keywords

  • Bovine serum albumin on silica
  • Isoelectric point
  • Protein adsorption
  • Single molecules
  • Total-internal-reflection fluorescence

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