Self-assembly of novel fluorescent quantum dot-cerasome hybrid for bioelectrochemistry

A novel fluorescent nanohybrid was fabricated via the self-assembly of semiconductive quantum dots (QDs) on biocompatible cerasomes. The nanohybrid (denoted as QDs-cerasome) was used as an electrode material for visible protein immobilization and bioelectrochemistry. The morphology and surface properties of the QDs-cerasome hybrid were characterized by transmission electron microscopies, atomic force microscopies and zeta potential measurements. Because the QDs-cerasome hybrid possessed a positive charge in aqueous solution, it could be used as a matrix to immobilize negatively charged hemoglobin (Hb) via electrostatic interaction. Ultraviolet-visible spectroscopy demonstrated that Hb was immobilized on the hybrid matrix without denaturation. The fluorescence of the QDs-cerasome was quenched as Hb was immobilized, indicating that the protein immobilization process could be visibly detected. Compared with protein electrodes constructed using a single-component material, including Hb-QDs/GC and Hb-cerasome/GC electrodes, the Hb-QDs-cerasome/GC electrode not only realized enhanced direct electrochemistry, but also displayed higher sensitivity and a wider linear range toward the detection of hydrogen peroxide because of the synergistic effect of the QDs and cerasomes. The experimental results demonstrate that this fluorescent multicomponent hybrid material provides a novel and effective platform to immobilize a redox protein to realize direct electrochemistry. As such, this hybrid shows promise for application in third-generation electrochemical biosensors.