Plasmonic Nanocavity-Driven Ultrafast Direct RT-qPCR for Point-of-Care Diagnostics

We report a plasmonic nanocavity thermocycler (PNT) for ultrafast direct real-time reverse transcription PCR (DRT-qPCR) at the point of care. The PNT features a layered structure of clustered gold, silicon dioxide, and gold thin film, achieving broadband visible absorption and efficient light-to-heat conversion under white light-emitting diode (LED) illumination. Achieving ramping rates of 20.4 °C/s (heating) and 7.5 °C/s (cooling), the PNT completes 40 cycles in 269 seconds. Combined with a microlens-array fluorescence microscope and a disposable PCR cartridge, the system performs direct amplification of SARS-CoV-2 from clinical swab samples in under 15 minutes, reaching 87.1% sensitivity, 100% specificity, and 93.3% accuracy. This ultrafast plasmonic nanocavity thermocycler presents a promising solution for accurate and decentralized molecular diagnostics.