Double-redox cycling signal amplification coupling Mo2C-graphyne-AuNPs modified electrode based photoelectrochemical assay for Aβ1-40 oligomers

As a very meaningful analytical technique the inherent high background signal makes photoelectrochemical assay imperfectible in real applications. Therefore, photoelectrochemistry based detection method with low blank noise and high ratio of signal to noise is highly appealing now. Herein we report a double-redox cycling signal amplification photoelectrochemical strategy with low-noise based on Mo2C-graphyne-AuNPs modified electrode. Mo2C-graphyne-AuNPs is synthesized used as photoelectroactive material. It is found that Hemin-AA-TCEP (Hemin-Ascorbic acid-Tris(2-carboxyethyl)phosphine) double-redox cycling system can greatly enhance the photoelectrochemical signal of Mo2C-graphyne-AuNPs. A PEC asssy for Alzheimer's disease marker, Aβ1−40 oligomers, is fabricated. In the PEC assay, AA is in-situ generated. In the absence of target, there is no AA being produced. It gives low background PEC noise. In the presence of target, AA is in-situ generated and AA-Hemin-TCEP double-redox cycling system is formed to enhance the PEC signal greatly and AA is recycled. Therefore, high PEC signal is achieved. So high sensitivity is gained. The detection limit as low as 3.3 aM was achieved for Aβ1−40 oligomers. This photoelectrochemical technology demonstrates a promising sensing platform using Mo2C-graphyne-AuNPs and Hemin-AA-TCEP double-redox cycling system to detect bioactive substance at ultralow levels.