Gold, carbon, and aluminum low-reflectivity compact discs as microassaying platforms.

Compact disc (CD) surface modification with different reflective materials offers new working perspectives as bioanalytical platforms. The potential of gold, carbon, and aluminum low-reflectivity compact discs as a substrate for microassaying is presented. CD polycarbonate bases were coated with these reflecting materials, maintaining optical properties. Probes immobilization onto reflective layers was studied by both passive adsorption and covalent linking. Different chemical modifications were made on substrates to provide functional groups capable of anchoring probes with primary amines covalently. Thus, self-assembled monolayers were performed by chemisorption of 11-mercaptoundecanoic acid on gold surfaces, and silanization with N-(trimethoxysilylpropyl)ethylenediamine triacetic acid on aluminum to provide a carboxylic acid functional group. Carbon oxidation with oxygen plasma afforded similar functionalization on the discs coated with this material. Performance of the studied materials as reflective layers was evaluated, and as proof of concept, a microimmunoassay for a neurotoxic compound was studied on the three surfaces. The results show the possibility of doing assays on this new supports with good analytical performances while maintaining discs' optical and mechanical properties to be read by a CD player.