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This work reports the first preparation and characterization of a hybrid PbS quantum dot (QD)/nanoporous NiO film nanostructure as well as its application for novel self-powered cathodic photoelectrochemical (PEC) sensing. Specifically, we synthesized the thioglycolic acid-capped PbS QDs and then assembled them onto the hydrothermally fabricated three-dimensional (3D) NiO nanostructured films on the transparent indium tin oxide-coated glass substrates, followed by the subsequent conjugation with the glucose oxidase as a model biocatalyst. Favorable alignment existed between the NiO and PbS QDs, and the as-obtained p-type heterostructure was characterized by various techniques and found to have good PEC activities. In the self-powered PEC biosensing of glucose, the system exhibited high sensitivity toward the presence of dissolved oxygen in the electrolyte, and thereby, a novel PEC enzymatic sensor was developed. With a PbS QD/3D NiO nanofilm, this work manifested the great promise of a heterostructure photocathode for a self-powered PEC biosensor that to the best of our knowledge has not been reported. We believe that it could inspire more interest in the design and development of numerous other p-type heterostructures for advanced self-powered PEC biosensors.

Herein we report the strategy of liposome-mediated Cu-induced exciton trapping upon CdS quantum dots (QDs) for amplified photoelectrochemical (PEC) bioanalysis application. Specifically, the Cu nanoclusters (NCs)-encapsulated liposomes were first fabricated and then processed with antibodies bound to their external surfaces. After the sandwich immunocomplexing, the confined liposomal labels were subjected to sequential lysis treatments for the release of Cu NCs and numerous Cu ions, which were then directed to interact with the CdS QDs electrode. The interaction of Cu ions with CdS QDs could generate CuS and form the trapping sites to block the photocurrent generation. Since the photocurrent inhibition is closely related with the Cu NCs-loaded liposomal labels, a novel and general "signal-off" PEC immunoassay could thus be tailored with high sensitivity. Meanwhile, a complementary "signal-on" fluorescent detection could be accomplished by measuring the fluorescence intensity originated from the Cu NCs. This work features the first use of Cu NCs in PEC bioanalysis and also the first NCs-loaded liposomal PEC bioanalysis. More importantly, by using other specific ions/reagents-semiconductors interactions, this protocol could serve as a common basis for the general development of a new class of liposome-mediated PEC bioanalysis.

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