Magnetically Controlled Dual-Mode Colorimetric/Photothermal CRISPR/Cas12a-Au@PtNPs Platform for Point-of-Care Detection of Group B Streptococcus

Group B Streptococcus (GBS) is a major cause of neonatal morbidity and mortality, underscoring the urgent need for rapid, accurate, and deployable diagnostics. Conventional culture and nucleic acid amplification tests are limited by long turnaround time, insufficient sensitivity, or dependence on sophisticated instrumentation, restricting their use in resource-limited settings. Here, we present a magnetically controlled dual-mode biosensing platform, termed c olorimetric/ p hotothermal–CRISPR/ Cas – Au @ Pt nanozyme (CP-CasAuPt), which integrates the sequence-specific trans-cleavage activity of CRISPR/Cas12a with the peroxidase-mimicking activity of Au@PtNPs. The catalytic oxidation of 3,3′,5,5′-Tetramethylbenzidine (TMB) generates oxidized TMB (oxTMB), which provides a visible colorimetric change and a near-infrared photothermal response, thereby enabling reliable dual-mode readouts with minimal instrumentation. Magnetic bead-assisted separation further reduces background signals, ensuring robust performance in complex matrices. Using GBS as a proof-of-concept, CP-CasAuPt achieved a detection limit of 10 3 CFU/mL after loop-mediated isothermal amplification, with results fully consistent with qPCR across 20 clinical samples. Beyond high sensitivity and specificity, this study establishes a generalizable strategy for multimodal molecular diagnostics, where orthogonal dual signals allow cross-validation, ensuring robust detection across diverse assay conditions. The CP-CasAuPt system thus offers a promising paradigm for rapid, instrument-free pathogen detection, particularly suited for resource-limited settings.