Label-free photoelectrochemical immunosensor based on CdTe/CdS co-sensitized TiO2 nanotube array structure for octachlorostyrene detection.

An octachlorostyrene (OCS) photoelectrochemical (PEC) immunosensor was developed by cross-linking anti-OCS antibody onto a CdTe/CdS-sensitized TiO2 nanotube arrays (NTAs). The anti-OCS polyclonal antibody was developed in rabbit as a result of immunization with BSA-OCS hapten conjugate. TiO2 NTAs were immobilized firstly with hydrothermally synthesized CdTe quantum dots (QDs), and then CdS which filled the spaces within the CdTe-TiO2 composite and encapsulated the CdTe QDs, forming an ideal stepwise bandedge structure, which benefited the light harvesting. The PEC immunosensor therefore shows high specificity and high sensitivity with a limit of detection of 2.58 pM, and a linear range from 5 pM to 50 nM. The testing time is 4 min. The analysis of river water reveals that the proposed sensor can be applied in the analysis of OCS in real water samples without complicated pre-treatments.