CRISPR/Cas12a coupled with In2O3/multiwalled carbon nanotube/PTCDA-EDA-DAP modified electrode self-powered photoelectrochemical assay for EBV-DNA

The design and engineering of photoelectroactive materials is recognized as a crucial step to regulate the performance of photoelectrochemical biosensing. Herein, an organic semiconductor polymer, PTCDA-EDA-DAP, was synthesized from perylene-3,4,9,10-tetracarboxylic dianhydride (PTCDA), ethylenediamine (EDA) and 1,3-diamino-2-propanol (DAP). In2O3/multiwalled carbon nanotube/PTCDA-EDA-DAP enable a stable and unchanging photocurrent in the range from 0 V to 0.3 V and an excellent self-powered photocurrent. Based on this superior photoelectrochemical property, we fabricated an ultrasensitive photoelectrochemical assay for EBV-DNA based on CRISPR/Cas12a double cycling signal amplification. The target DNA stimulated Nt.BsmAI nicking, extension growth and a short chain nucleic acid as secondary targets being generated. The secondary target initiated next round of polymerization/cleavage. So that, after the two rounds of slicing and prolongation growth, the exponential growth dsDNA was generated resulting dsDNA bound to the Cas12a-crRNA complex, the trans-cleavage activity of Cas12a was activated, and resulted in amplified photocurrent. This photoelectrochemical assay had a LOD of 45 aM. The successful detection of EBV-DNA in serum samples demonstrated the promising application in real samples.