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Keywords:

  • Electrochemical desorption;
  • Alkanethiols;
  • Surface-bound proteins;
  • Controlled removal;
  • Surface plasmon resonance;
  • Electrochemistry

Abstract

The goal of this study was to enable rational modulation of biological interfaces using electrochemical desorption of surface-bound proteins. Coupled, surface plasmon resonance (SPR) – electrochemistry instrument was used to monitor molecular assembly events on gold electrodes and to correlate these events with changes in electrochemical properties of the substrate. Model proteins, bovine serum albumin (BSA) and immunoglobulin G (IgG), were conjugated via carbodiimide (EDC) chemistry to a layer of mercaptoundecanoic acid (MUA) assembled on SPR sensor surface. Deposition of alkanethiols and proteins were monitored by ellipsometry and SPR techniques, and was further confirmed by cyclic voltammetry with potassium ferricyanide serving as a reporter molecule. The surface-bound proteins were completely removed by applying a reductive potential of −1200 mV vs. Pt electrode in a physiological saline buffer. Importantly, the sequence of protein immobilization followed by desorption could be repeated multiple times, thus demonstrating ability to modulate interfacial properties. Controlled removal of protein molecules from electrode surfaces is envisioned to have important applications in affinity or cell-based biosensing, cellular micropatterning and cell sorting.