Nanoscale glassification of gold substrates for surface plasmon resonance analysis of protein toxins with supported lipid membranes

Anal Chem. 2006 Jan 15;78(2):596-603. doi: 10.1021/ac051644y.

Abstract

Surface plasmon resonance (SPR) spectroscopy, a powerful tool for biosensing and protein interaction analysis, is currently confined to gold substrates and the relevant surface chemistries involving dextran and functional thiols. Drawbacks of using self-assembled monolayers (SAMs) for SPR-related surface modification include limited stability, pinhole defects, bioincompatibility, and nonspecific protein adsorption. Here we report the development of stable nanometer-scale glass (silicate) layers on gold substrates for SPR analysis of protein toxins. The nanoscale silicate layers were built up with layer-by-layer deposition of poly(allylamine hydrochloride) and sodium silicate, followed by calcination at high temperature. The resulting silicate films have a thickness ranging from 2 to 15 nm and demonstrate outstanding stability in flow cell conditions. The use of these surfaces as a platform to construct supported bilayer membranes (SBMs) is demonstrated, and improved performance against protein adsorption on SBM-coated surfaces is quantified by SPR measurements. SBMs can be formed reproducibly on the silicate surface via vesicle fusion and quantitatively removed using injection of 5% Triton X-100 solution, generating a fresh surface for each test. Membrane properties such as lateral diffusion of the SBMs on the silicate films are characterized with photobleaching methods. Studies of protein binding with biotin/avidin and ganglioside/cholera toxin systems show detection limits lower than 1 microg/mL (i.e., nanomolar range), and the response reproducibility is better than 7% RSD. The method reported here allows many assay techniques developed for glass surfaces to be transferred to label-free SPR analysis without the need for adaptation of protocols and time-consuming synthetic development of thiol-based materials and opens new avenues for developing novel bioanalytical technologies for protein analysis.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Avidin / chemistry
  • Biotin / chemistry
  • Cholera Toxin / physiology
  • Gangliosides / physiology
  • Gold / chemistry*
  • Nanostructures / chemistry*
  • Polyamines / chemistry
  • Protein Binding / physiology
  • Silicates / chemistry*
  • Surface Plasmon Resonance / methods*

Substances

  • Gangliosides
  • Polyamines
  • Silicates
  • Avidin
  • polyallylamine
  • Biotin
  • Gold
  • Cholera Toxin