Photoelectrochemical Sensing of α-Synuclein Based on a AuNPs/Graphdiyne-Modified Electrode Coupled with a Nanoprobe
Ting Yao, Ruhao Wang, Yuchan Meng, Xu Hun
Abstract
We developed a method for photoelectrochemical (PEC) sensing based on a AuNPs/graphdiyne, as a low background signal composite material, modified electrode coupled with a nanoprobe (probe DNA/DA/MBA/WSe2) for sensitive α-synuclein (α-Syn) detection. A tungsten selenide (WSe2) nanoflower was first produced with a one-pot solvothermal method and employed as a signal amplification element and the modified substrate of the nanoprobe. The synergy effect between the WSe2 nanoflower and graphdiyne (GDY) can reduce the photoinduced electron–hole recombination and expedite the spatial charge separation. Due to the synergistic effect of AuNPs/GDY and WSe2, this detection strategy provides a high signal-to-noise ratio and good performance. The signal indicator, dopamine/4-mercaptophenyl boronic acid/WSe2 (DA/MBA/WSe2), was generated with the recognition of boron–diol. In the presence of the α-Syn oligomer, the target triggered cycle I strand displacement amplification and achieved the conversion of the α-Syn oligomer to a massive output of false-target DNA (FT). The output FT was used for the cycle II catalytic hairpin assembly onto the electrode which was modified with AuNPs/GDY and triple-stranded DNA (TsDNA); thereby, plenty of PEC nanoprobes which are composed of probe DNA and the signal indicator are captured, and the photocurrent response is produced correspondingly. This PEC biosensor generated a strong photocurrent with low blank (27.6 nA) and was sensitive to α-Syn oligomer. The limit of detection was 3.3 aM, and the relative standard deviation (RSD) was 3.7% at 100 aM. Moreover, it also has good selectivity, indicating promising potential in clinical diagnostics.