Application of colloidal gold in protein immobilization, electron transfer, and biosensing

Direct electron transfer between redox proteins and electrodes is of practical and theoretical interest and can be improved by electrode or protein modification. The direct contact of protein with electrode surfaces can lead to a significant change of the protein structure and/or function. Immobilized colloidal gold on electrode surfaces provides a microenvironment similar to that of the redox protein in native systems and gives the protein molecules more freedom in orientation, thus reducing the insulating property of the protein shell for the direct electron transfer and facilitating the electron transfer through the conducting tunnels of colloidal gold. This brief review focuses on the current state of the colloidal gold used for protein immobilization, electron transfer and biosensing, with emphasis on recent advances, challenges and trends.