One-Pot Photocontrolled CRISPR-Cas12b Coupled with Loop-Mediated Isothermal Amplification Assay for Point-of-Care Test of Mycoplasma pneumonia.

Mycoplasma pneumoniae (MP) is a highly prevalent respiratory pathogen, making the development of point-of-care testing (POCT) methods for its detection essential. The integration of loop-mediated isothermal amplification (LAMP) with CRISPR-Cas12b systems demonstrates remarkable specificity and offers promising potential for MP POCT application. However, the current one-pot LAMP/CRISPR-Cas12b system (HOLMESv2) faces the challenge of low sensitivity due to the premature cleavage of the template by CRISPR, which limits its practical utility. To address this, this study introduces a photocontrolled HOLMESv2 (pHOLMESv2) assay using gRNA with an NPOM-modified spacer region. This modification prevents full base pairing between the gRNA and MP DNA, thereby keeping the CRISPR-Cas12b system in an inactive condition during the LAMP reaction and avoiding unintended cleavage of the DNA template. After completion of the LAMP reaction, light irradiation eliminates the NPOM group from the gRNA, restoring its activity to cleave the LAMP products, resulting in a fluorescence signal. The pHOLMESv2 assay successfully addresses the issue of premature DNA template cleavage, improving the limit of detection (LoD) by 133-fold (7.5 copies/μL). Additionally, this method enables direct detection of samples treated with nucleic acid release agents, eliminating the need for complex extraction, and features lyophilized reagents for enhanced stability, storage, and transport. The efficacy of pHOLMESv2 was assessed with 160 clinical MP samples, achieving a sensitivity of 99.0% and a specificity of 100.0%. The pHOLMESv2 assay, when combined with the developed smartphone-based amplification reader, provides a highly sensitive, specific, portable, and cost-effective MP detection, indicating its potential for significant diagnostic use.