Electrochemical sensing of bovine serum albumin at self-assembled SWCNTs on gold

A wet chemical approach for self-assembly of oxidative single-walled carbon nanotubes (SWCNTs) on gold was developed. This method was based on spontaneous adsorption of SWCNTs to the gold surface via Au–S bonds using sonication in a mixture of concentrated sulphuric and nitric acids. The self-assembly of SWCNTs on gold was confirmed using Raman spectroscopy, atomic force microscopy, and high resolution X-ray photoelectron spectroscopy. The resultant SWCNT-Au electrodes were fabricated by using a thiol group of cysteamine at the chain end that was connected to gold and a carboxyl group of SWCNTs at the other chain end for anchoring the amino groups of proteins. Cyclic voltammetric detection of bovine serum albumin (BSA) was applied to investigate the influence of assembly time on the biosensing behavior of the electrodes. The self-assembled SWCNT-Au sensors have shown an excellent sensitivity and a dynamic linear response for BSA in the range of 0.1 to 1.2 µM.