Multifunctional Ethyl Violet@NH₂-MIL-88B(Fe) Hybrids: CRISPR-Cas12a-Assisted PEC-FL-CL Triple-Mode Sensitive Detection of HPV-16

The multimode assay based on multiple response mechanisms has received great attention to effectively improve the accuracy of a sensing platform. However, multifunctional sensing materials for simultaneously satisfying the multiple-mode detections are still in shortage due to the incompatibility of the signal transduction mechanisms in different modes. Here, taking human papillomavirus 16 (HPV-16) DNA (TDNA) as the model due to its important role in cervical cancer, a novel multifunctional material, ethyl violet (EV)@NH₂-MIL-88B(Fe) (ENM) hybrids, have been successfully prepared, which could simultaneously satisfy CRISPR-Cas12a-assisted photoelectrochemical (PEC)-fluorescent (FL)-colorimetric (CL) triple-mode detection of TDNA. Based on the TDNA-induced trans-cleavage ability of CRISPR-Cas12a and efficient separation of magnetic beads, ENM was obtained from the single-stranded DNA-surrounded streptavidin-modified magnetic beads-ENM (SMB-ssDNA-ENM) and decomposed by pyrophosphate to get free EV, 2-aminoterephthalic acid (NH₂-BDC), and Fe³⁺. Thus, TDNA was sensitively detected based on the EV-enhanced PEC signal of SnS₂ nanosheets (PEC mode), fluorescent signal of NH₂-BDC (FL mode), and characteristic absorption peak at about 720 nm of Fe³⁺-induced Prussian blue (PB) (CL mode). The designed PEC-FL-CL triple-mode biosensing platform had good performance for the detection of TDNA with a wide linear range (0.1 fM-100 nM) and ultralow detection limits (0.07 fM for PEC, 0.03 fM for FL and 0.09 fM for CL). Additionally, the developed PEC-FL-CL triple-mode biosensing platform has great potential for applications in early disease diagnosis and bioanalysis, as it can be easily extended to other DNA assays through modification of the crRNA sequence within the CRISPR-Cas12a system.