In this work, a click reaction-triggered wavelengthresolved dual-signal output photoelectrochemical (PEC) biosensor with DNAzymes-assisted cleavage recycling amplification was proposed for sensitive triplex metal ions assay. Substantial DNA fragments azido-S 1 and azido-S 2 , derived from the Pb 2+ (target 1) and Mg 2+ (target 2) dependent cleavage cycle of DNAzymes, respectively, were grafted efficiently on the same alkynyl-DNA (capture DNA) modified electrode via the Cu 2+ (target 3) and ascorbic acid (AA) cocatalyzed click reaction, which thus could be subsequently used for immobilization of two different photoactive nanomaterials labeled with single DNA to generate distinguishing dual-signal output for simultaneously sensitive detection of Pb 2+ and Mg 2+ . Furthermore, the control variable method was used for detecting Cu 2+ by altering the concentration of Cu 2+ in the click reaction. Owing to the usage of the click reaction and target-converted signal amplifying strategy, the utilization rate of cycle output DNAs was largely increased, significantly improving the detection sensitivity of the proposed approach. As a result, low detection limits down to picomolar were acquired for the detection of Pb 2+ , Mg 2+ , and Cu 2+ , providing a versatile, efficient, and sensitive PEC method for multiple assays of various targets such as metal ions, small molecules, and tumor markers.

No abstract

In this work, hydrazine-functionalized perylene diimide derivative supramolecular (HPDS), a novel self-enhanced donor–acceptor-donor (D-A-D) type aggregates with excellent photoelectric activity, was synthesized by a facile one-pot green route and further applied in construction of coreactant-free photoelectrochemical (PEC) biosensor for ultrasensitive DNA assay. Impressively, the HPDS formed by D-A-D units not only possessed effectively shorted electron-transfer path between donor and acceptor, but also presented a desiring aggregate state via the π–π stacking of perylene core and hydrogen bonding of the terminal moiety, thereby acquiring a high density electron flow for generating the extremely high PEC signal. Experimental data showed that the well film-formed HPDS aggregate could produce an exciting photocurrent intensity about 6-fold stronger than that of precursor perylene dianhydride with donor N2H4 in detection buffer and even 12-fold than that of perylene dianhydride only. In this respect, the resultant HPDS aggregate as a novel self-enhanced PEC signal tag was adopted to fabricate the coreactant-free PEC biosensor with the help of target dual-recycling-induced bipedal DNA walker cascade amplification strategy for ultrasensitive DNA (a fragment of TP53 gene) assay. The proposed biosensor showed a high sensitivity with a low detection limit down to femtomole level, providing a new avenue for sensitive bioanalysis and clinical diagnosis.

No abstract

No abstract