Selective photoelectrochemical architectures for biosensing: Design, mechanism and responsibility

Photoelectrochemical (PEC) biosensing is a newly developed and promising analytical technique. The complete separation of excitation source (light) and detection signal (current) greatly reduces the undesired background signal, which is advantageous over both optical and electrochemical determination. Using a photocurrent from the PEC process as a detection signal, PEC biosensor can be operated at a low applied potential and exhibits high sensitivity with repeating cycles. In this account, we summary recent results in the study on PEC biosensing. To construct PEC sensors, exciting light sources of chemiluminescence (CL) and electrochemiluminescence, and PEC active materials including the selected semiconductors, dyes, composites of semiconductors-semiconductors and hybrids of dyes-semiconductors are employed. The principle of PEC biosensing is described and the mechanism in anodic and cathodic photocurrent generation processes is well investigated. On the other hand, in typical PEC biosensors, biomolecules such as antibodies and nucleic acids, are immobilized on the biosensing interface and bind with their corresponding targets via chemical reaction or biological recognition, enabling quantitative detection of the targets possible according to the variation of the photocurrents. Finally, several examples with the PEC biosensing application including immunosensors, DNA sensors, RNA sensors, aptasensors, enzymatic analysis, cytosensors, and detection of small molecules and metal ions are briefly introduced.