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A platelike tungsten trioxide (WO 3 ) sensitized with CdS quantum dots (QDs) heterojunction is developed for solar-driven, real-time, and selective photoelectrochemical (PEC) sensing of H 2 O 2 in the living cells. The structure is synthesized by hydrothermally growing platelike WO 3 on fluorine doped tin oxide (FTO) and subsequently sensitized with CdS QDs. The as-prepared WO 3 -CdS QDs heterojunction achieve significant photocurrent enhancement, which is remarkably beneficial for light absorption and charge carrier separation. Based on the enzymatic etching of CdS QDs enables the activation of quenching the charge transfer efficiency, thus leading to sensitive PEC recording of H 2 O 2 level in buffer and cellular environments. The results indicated that the proposed method will pave the way for the development of excellent PEC sensing platform with the quantum dot sensitization. This study could also provide a new train of thought on designing of self-operating photoanode in PEC sensing, promoting the application of semiconductor nanomaterials in photoelectrochemistry. [ABSTRACT FROM AUTHOR]

In this work, a “signal-off” photoelectrochemical DNA sensing strategy was proposed on the basis of the DNA hybridization induced conformational conversion using CdS quantum dots (QDs) sensitized titanium oxide (TiO 2 ) nanorod array as photoactive material. Highly oriented, single-crystalline TiO 2 nanorod arrays were grown directly on fluorine doped tin oxide (FTO) substrate by the hydrothermal method and employed as matrix for immobilization of capturing hairpin DNA probe, whereas CdS QDs as visible light antennae were successively labeled on the terminal of capturing hairpin DNA probe. Compared with pure TiO 2 nanorods array, CdS QDs sensitized TiO 2 nanorods array evidently extended the absorption edge and exhibited enhanced photoelectrochemical response in the visible region. In the absence of the target DNA, the direct attachment of CdS QDs to TiO 2 nanorod array could reduce charge recombination and hence amplify photocurrent intensity. While in the presence of target DNA, the specific recognition of the target DNA with the capturing hairpin DNA–CdS probe would trigger the conformational conversion of capturing hairpin DNA–CdS probe leading to the quenching of photocurrent. Under optimized conditions, this “signal-off” photoelectrochemical sensing strategy shows a linear relationship between photocurrent variation and the logarithm of target DNA concentration in the range from 10 aM to 100 pM with a detection limit of 5.2 aM. Moreover, it exhibits good performance of excellent specificity, high stability, and acceptable fabrication reproducibility. This present strategy opens an alternative avenue for photoelectrochemical signal transduction and expands the applications of photoelectrochemical biosensing and clinical diagnosis. [ABSTRACT FROM AUTHOR]

In this work, a novel sensing platform based on visible light driven biofuel cell (BFC) has been facilely designed for sensitive detection of prostate-specific antigen (PSA) with the photo-response bioanode, realizing the dual route energy conversion of light energy and chemical energy to electricity. The hierarchical branched TiO 2 nanorods (B-TiO 2 NRs) decorated with CdS quantum dots (QDs) act as the substrate to confine glucose dehydrogenase (GDH) for the visible light driven glucose oxidation at the bioanode. Three dimensional flowers like hierarchical carbon/gold nanoparticles/bilirubin oxidase (3D FCM/AuNPs/BOD) bioconjugate served as biocatalyst for O 2 reduction at the biocathode. With an increase in the concentration of PSA, the amount of BOD labels on biocathode increases, thus leading to the higher current output of the as-proposed visible light driven BFC. Based on this, this sensing platform provide great performance in sensitivity and specificity, increasing linear detection range from 0.3 pg mL −1 to 7 μg mL −1 with a detection limit of 0.1 pg mL −1 . Most importantly, our new sensing strategy provided a simple and inexpensive sensing platform for tumor markers detection, suggesting its wide potential applications for clinical diagnostics. [ABSTRACT FROM AUTHOR]