Enhanced two-electrode photoelectrochemical biosensing platform amplified by bilirubin oxidase labelling

An efficient two-electrode strategy with the amplification of BOD label was first put forward to develop a novel PEC biosensing platform with high sensitivity and good selectivity in real biological matrix. • An efficient two-electrode strategy amplified by BOD labelling was proposed to build PEC biosensing platform. • The ZIS/Fe:TiO 2 photoanode as signal conservation element presented a remarkable photocurrent output. • The BOD-guided signaling strategy for O 2 reduction reaction could change current detection signal evidently. • The PEC biosensing platform demonstrated high sensitivity and good selectivity in real biological matrix. Herein, a novel and robust two-electrode photoelectrochemical (PEC) biosensing platform amplified by bilirubin oxidase (BOD) labelling was reported. This two-electrode operating system was composed of photoanode and sensing biocathode. Carcinoembryonic antigen (CEA) was utilized as a model for probing. Specifically, Fe 3+ -doped TiO 2 (Fe:TiO 2 ) nanotubes were first prepared and then deposited with ZnIn 2 S 4 (ZIS) nanocrystals to develop the ZIS/Fe:TiO 2 photoanode. Toward sensing biocathode, after carbon nanotubes (CNTs) and Au nanoparticles (NPs) were modified on conductive glass, an Au/CNT cathodic substrate was fabricated to anchor the CEA aptamer. Complementary DNA (cDNA) of the CEA aptamer was labelled with BOD to form the cDNA-BOD conjugate that amplified the signal through DNA hybridization. Target detection hinged on an evident decline in the current signal generated by terminated amplification of the BOD labels and evident steric hindrance of the captured CEA molecules. Profiting from excellent PEC property of the ZIS/Fe:TiO 2 photoanode and good oxygen-reduction capability of the BOD labels, the two-electrode PEC biosensing platform exhibited high sensitivity. Because of the division of biorecognition with photoanode, the platform also showed satisfactory selectivity in biological matrix. This elegant two-electrode strategy offers a promising path for seeking other robust PEC biosensors applying in complex biological samples.