A sandwich-type photoelectrochemical sensor based on tremella-like graphdiyne as photoelectrochemical platform and graphdiyne oxide nanosheets as signal inhibitor

Abstract Graphdiyne (GDY) was the first reported graphynes to be prepared practically. Owing to its low dispersibility, only very limited GDY-based hybrids were synthesized. Furthermore, no any high quality of GDY-based hybrid with photoelectrochemical performance was synthesized by simple hydrothermal process. Herein, we report acidified tremella-like GDY nanotubes. The dispersibility of GDY was highly improved. The composite of GDY and cadmium sulfide quantum dots (GDY-CdSQDs) was synthesized through one-step hydrothermal method. GDY-CdSQDs exhibited excellent photocurrent response under optical illumination. Small size of GDY oxide (GDYO) nanosheet was obtained through oxidation and size screening. A photocurrent signal inhibitor was thus prepared by covalently binding DNA probe 2 (P2) on GDYO nanosheet (P2-GDYO). With GDY-CdSQDs and DNA capturing probe 1 (P1) acting as photoelectrochemical sensing platform, the target object of microRNA-21 (miR-21) was captured by P1 and hybridized with P2-GDYO. Because GDYO exhibited low conductivity, high loading capacity for insulative P2, and surface absorption to light irradiation, it caused a magnified photocurrent change. The changed photocurrent was used to quantitatively detect miR-21. This method avoided expensive bioreagents and labeled target/detection DNA or miRNAs. It was potential for other bioanalysis and clinic diagnosis.