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This work is the first report on the energy transfer between CdS quantum dots and Au nanoparticles for photoelectrochemical biosensing applications. [ABSTRACT FROM AUTHOR]

This work reports the use of compositionally heterogeneous asymmetric Ag@Au core–satellite nanoassembly functionalized with DNA sequence as unique signaling nanoprobes for the realization of new energy-transfer-based photoelectrochemical (PEC) immunoassay of prostate- specific antigen (PSA). Specifically, the Ag@Au asymmetric core–satellite nanoassemblies (Ag@Au ACS) were fabricated on a two-dimensional glass substrate by a modified controlled assembly technique, and then functionalized with DNA sequences containing PSA aptamers as signaling nanoprobes. Then, the sandwich complexing between the PSA, its antibodies, and the signaling nanoprobes was performed on a CdS QDs modified indium tin oxide (ITO) electrode. The single stranded DNA can server as a facile mediator that place the Ag@Au ACS in proximity of CdS QDs, stimulating the interparticle exciton–plasmon interactions between Ag@Au ACS and CdS QDs and thus quenching the excitonic states in the latter. Since the damping effect is closely related to the target concentration, a novel energy-transfer-based PEC bioanalysis could be achieved for the sensitive and specific PSA assay. The developed biosensor displayed a linear range from 1.0×10 −11 g mL −1 to 1.0×10 −7 g mL −1 and the detection limit was experimentally found to be of 0.3×10 –13 g mL −1 . This strategy used the Ag@Au ACS-DNA signaling nanoprobes and overcame the deficiency of short operating distance of the energy transfer process for feasible PEC immunoassay. More significantly, it provided a way to couple the plasmonic properties of the Ag NPs and Au NPs in a single PEC bioanalytical system. We expected this work could inspire more interests and further investigations on the advanced engineering of the core–satellite or other judiciously designed nanostructures for new PEC bioanalytical uses with novel properties. [ABSTRACT FROM AUTHOR]

A novel photoelectrochemical (PEC) sensor for mercury ions (Hg 2 + ) was fabricated based on the energy transfer (ET) between CdS quantum dots (QDs) and Au nanoparticles (NPs) with the formation of T–Hg 2 + –T pairs. In the presence of Hg 2 + ions, a T-rich single-strand (ss) DNA labeled with Au NPs could hybridize with another T-rich ssDNA anchored on the CdS QDs modified electrode, through T–Hg 2 + –T interactions, rendering the Au NPs in close proximity with the CdS QDs and hence the photocurrent decrease due to the ET between the CdS QDs and the Au NPs. Under the optimal condition, the photocurrent decrease was proportional to the Hg 2 + concentration, ranging from 3.0 × 10 − 9 to 1.0 × 10 − 7 M, with the detection limit of 6.0 × 10 − 10 M. [ABSTRACT FROM AUTHOR]

Abstract: A sensitive photoelectrochemical (PEC) approach for Pb2+ sensing was achieved firstly with the coupling of G-quadruplex-based DNAzyme and biocatalytic precipitation (BCP) on a CdS quantum dots electrode. Pb2+ can induce the conformational change of K+-stabilized G-quadruplex-based DNAzyme, leading to the decrease of the catalytic activity to H2O2-mediated 4-chloro-1-naphthol oxidation (BCP reaction). From the respective BCP reaction that monitors the event of DNAzyme deactivation, a novel PEC Pb2+ sensor could be realized with a detection limit of 1.0×10−8 M. [Copyright &y& Elsevier]

Abstract: The coupling of biocatalytic precipitation (BCP) to photoelectrochemical (PEC) biosensing for the development of rapid PEC sensors with ultrahigh sensitivity and excellent anti-interference ability is successfully realized. Horseradish peroxidase (HRP) was immobilized on the matrix of TiO2/CdS and 4-chloro-1-naphthol (4-CN) was chosen for the BCP-amplified PEC detection of H2O2. The HRP accelerated oxidation of 4-CN by H2O2 would yield insoluble product on the photoelectrode surface, on the basis of which the photocurrent be influenced. The detection limit of 5.0×10−10 M (S/N=3) for the determination of H2O2 was achieved. [Copyright &y& Elsevier]