Endogenous fluorescent metal-organic framework ratio fluorescence sensing strategy: Combining CRISPR/Cas12a for ultra-sensitive detection of tetracycline

CRISPR/Cas12a can activate trans-cleavage activity upon single-stranded DNA binding, making it widely applicable in highly sensitive fluorescent biosensors. Sensors utilizing monochromatic fluorescence output modes are susceptible to interference from multiple factors, resulting in unstable detection methods. To address this, we designed a ratio-based fluorescence sensor for detecting tetracyclines (TCs) based on the synergistic signal amplification of nucleic acid aptamer (42TET) and zirconium-based metal-organic framework (PCN-224) with CRISPR/Cas12a. PCN-224 adsorbs single-stranded DNA, quenching its FAM-labeled fluorescence while simultaneously emitting its own fluorescent signal. This dual-fluorescence output reduces background interference and enhances detection accuracy. By designing an activator as a complementary sequence (cDNA) to the nucleic acid aptamer, the system binds to 42TET in the presence of tetracycline, releasing the cDNA to activate the CRISPR/Cas12a system. Through this system's signal amplification capability, highly sensitive detection of tetracycline is achieved, with a detection limit reaching 8.7 nM. It possesses the same detection capabilities as traditional HPLC detection methods. This method is simple, rapid, efficient, and highly quantitative, offering broad prospects for future applications.