Surface plasmon resonance-enhanced cascaded sensitization effect of CuInSe₂/Cu₃(BTC)₂/Y:ZnO photosensitive structures enabled lab-on-paper photoelectrochemical bioassay

Herein, the surface plasmon resonance (SPR)-enhanced cascaded sensitization effect of CuInSe2/Cu-3(BTC)(2)/yttrium doped ZnO (Y:ZnO) photosensitive structures were integrated on lab-on-paper photoelectrochemical (PEC) biosensing platform for the ultrasensitive detection of microRNA-21 (miRNA-21) based on entropy-driven strand displacement amplification (SDA) propelled DNAzyme roller amplification strategy. The Y element doping equipped the paper-based Y:ZnO nanorods with enhanced PEC performance, which was further cosensitized with Cu-3(BTC)(2) metal-organic framework (MOF) and CuInSe2 quantum dots (QDs), giving a cascaded sensitization effect for generating a robust and stable photocurrent signal. The SPR effect between CuInSe2 QDs and Au nanoparticles (NPs) was activated with the aid of entropy-driven SDA propelled DNAzyme roller amplification-induced conversion of target miRNA-21 to Au NPs-labelled track DNA (track DNA-Au), which could effectively promote the photogenerated carrier separation and transfer of CuInSe2/Cu-3(BTC)(2)/Y:ZnO cascade sensitized structures via hot-electron transfer mechanism, further enhancing the photocurrent signal. Based on this designed "signal-on" mode, the quantitative detection of miRNA-21 was achieved with high sensitivity, good specificity, and excellent practicability, which provided a promising model for developing lab-on-paper diagnostic tool for biomedicine.