Photo/Electrochemical Sensing of Bio-analytesNaimeh Naseri
Sensitive and selective target capture, recognition, and signal transduction in detection of chemical and biological molecules is essential for fundamental biomedical studies, disease diagnosis, and drug screening. To achieve fast, sensitive, large-scale, and low-cost molecular analysis, a wide variety of detection technologies such as fluorescent, spectroscopic, electrical, magnetic and mechanical methods have been developed.
The photoelectrochemical (PEC) approach is a recently developed one for biomolecular analysis. The basic principle of PEC is the photo-to-electric conversion of a semiconducting material, phot-excited electrons or holes are transferred to proper sites to initiate redox reactions. This photon-to-charge conversion process is highly sensitive to the surface chemistry and microenvironment fluctuation. When the semiconductor surface is functionalized with a receptor layer that can specifically recognize and bind to bio analyte in the solution, the photocurrent density of the semiconductor is changed. For the electron transfer, the driving force is the energy difference between the conduction band of the semiconductor and the reduction potential of the acceptor redox couple. Compared to conventional electrochemical methods, the PEC detection usually benefits from advantages like high sensitivity, simple instrumentation and low cost. In addition, in PEC detection, two separate forms of energy are employed for signal production in which irradiated light excites the photoactive species and the electrical signal is subsequently transduced and detected leading to reduced background and potentially higher sensitivity. To learn more about principles and state of the art in the subject, these papers are strongly suggested: