Rapid Detection of SARS-CoV-2 via Photothermal Reverse Transcription qPCR Using Octahedral Gold Nanoframes

• Photothermal RT-qPCR enabled the detection of SARS-CoV-2 within 25 minutes. • Octahedral hollow gold nanostructures and gold nanoframes served as photothermal agents. • Octahedral gold nanoframes effectively enabled photothermal RT-qPCR. • Rapid thermal cycling enabled by NIR-driven plasmonic heating and feedback control. • The Photothermal RT-qPCR platform provides rapid, sensitive, and portable diagnostics for the detection of viral RNA. Rapid and accurate detection of viral RNA is crucial for controlling infectious diseases and facilitating point-of-care diagnostics. Here, we present a photothermal reverse transcription quantitative PCR (PT-RT-qPCR) platform that employs structurally engineered octahedral gold nanoframes as photothermal heating agents. These nanoframes not only exhibit efficient heat generation under near-infrared (NIR) laser irradiation—owing to their plasmonic resonance in the NIR region—but also promote effective heat dissipation due to their high surface-to-volume ratio, enabling efficient and uniform thermal cycling. When applying the developed system to detect SARS-CoV-2 RNA, we successfully achieved highly sensitive and quantitative amplification within 25 minutes. For comparison, we employed octahedral Au nanoparticles and hollow Au nanoparticles. The plasmonic resonance of the former lies outside the excitation range of the NIR laser, while the latter exhibits spectral overlap with the NIR irradiation wavelength but lacks a porous surface structure, resulting in inefficient heat dissipation. As anticipated, both control structures demonstrated either non-optimal photothermal conversion or poor heat management, ultimately yielding lower sensitivity in PT-qPCR assays compared to the octahedral gold nanoframes, which exhibited markedly enhanced performance. The platform showed clear amplification curves and reliable quantification across serial RNA dilutions. This study emphasizes the potential of geometrically and optically tailored plasmonic nanomaterials for enhancing molecular diagnostics, supporting the development of rapid, portable PCR-based testing solutions.