Hierarchical CuInS₂-based heterostructure: Application for photocathodic bioanalysis of sarcosine

In this study, on the basis of hierarchical CuInS₂-based heterostructure, a novel cathodic photoelectrochemical (PEC) enzymatic bioanalysis of the sarcosine detection was reported. Specifically, heterostructured CuInS₂/NiO/ITO photocathode was prepared and sarcosine oxidases (SOx) were integrated for the construction of the enzymatic biosensor. In the bioanalysis, the O₂-dependent suppression of the cathodic photocurrent can be observed due to the competition between the as-fabricated O₂-sensitive photocathode and the SOx-catalytic event toward O₂ reduction. Based on the sarcosine-controlled O₂ concentration, a novel photocathodic enzymatic biosensor could be realized for the sensitive and specific sarcosine detection. This work manifested the great potential of CuInS₂-based heterostructure as a novel platform for future PEC bioanalytical development and also a PEC method for sarcosine detection, which could be easily extended to numerous other enzymatic systems and to our knowledge has not been reported. This work is expected to stimulate more interest in the design and implementation of numerous CuInS₂-based heterostructured photocathodic enzymatic sensing.