Fig. 1. Working principle diagrams of CRISPR/Cas systems^[3]

Fig. 2. Schematic of CRISPR/Cas -PCR platforms for nucleic acid detection. (a) Diagnostic platform for the detection of COVID-19 RNA^[10]; (b) diagnostic platform for the detection of nocardia farcinica^[11]; (c) diagnostic platform for the detection of HBV DNA^[13]

Fig. 3. Schematic diagrams of the CRISPR/Cas-RPA nucleic acid detection methods. (a) Flowchart of viral DNA/RNA detection using SHERLOCK technology^[15]; (b) experimental flowchart of CRISPR/Cas12a-RT-RPA based lateral flow detection^[21]; (c) schematic diagram of HIV detection based on CRISPR/Cas12a-RT-RPA system^[24]

Fig. 4. Schematic diagrams of CRISPR/Cas-SPR method for nucleic acid detection. (a) A CRISPR/Cas12a-SPR biosensor for detecting SARS-CoV-2 variant^[27]; (b) a CRISPR/Cas9-SPR biosensor for detecting target sequences in genomic DNA from Duchenne muscular dystrophy patients^[28]; (c) DNA origami technology combined with CRISPR/Cas12a-SPR biosensors for detecting the T790M mutation in the EGFR gene and the G12C mutation in the KRAS gene^[29]; (d) a fiber-optic tip biosenser-based CRISPR/Cas12a-SPR-FT system for the detection of monkeypox virus^[30]

Fig. 5. Schematic diagrams of CRISPR/Cas-SERS technologies for nucleic acid detection. (a) A CRISPR/Cas12a-mediated gold nanoparticle aggregation-based SERS platform for HPV DNA detection^[34]; (b) a CRISPR/Cas12a-mediated liposome-amplified strategy for dual-mode signal detection of target DNA^[35]; (c) a CRISPR/Cas12a-SERS technology combined with a lateral flow assay for HIV-1 dsDNA detection^[36]; (d) a CRISPR/Cas9-SERS technology combined with a lateral flow assay for detecting Staphylococcus aureus DNA^[37]

Fig. 6. Schematic diagrams of CRISPR/Cas-electrochemical sensors for nucleic acid detection. (a) A CRISPR/Cas12a-electrochemical sensor for detecting HPV-16 DNA and PB-19 DNA^[40]; (b) a CRISPR/Cas12a-electrochemical sensor functionalized with DNA probes that undergo conformational changes in the presence of target DNA^[41]; (c) an electric field-enhanced CRISPR/Cas12a-electrochemical sensor^[42]; (d) a gold nanoparticle-assisted CRISPR/Cas12a-electrochemical sensor for detecting SARS-CoV-2 variant^[43]