Plasmonic colorimetric PCR for Rapid molecular diagnostic assays

The development of efficient and sensitive diagnostic method with no need for bulky and expensive instrumentation is of great importance in early detection and large-scale prevention of various infectious disease. Herein, we introduce a plasmonic photothermal colorimetric PCR (PPT-cPCR) for fast, sensitive, cheap, and simple nucleic acid detection. Our platform utilizes ultrafast PCR amplification based on the photothermal effect of plasmonic magnetic nanoparticles and color change by oxidation of chromogenic substrates caused by the photocatalytic activity of fluorescent dyes. PPT-cPCR has successfully shown that DNA targets ranging from 0.5 ng μL⁻¹ to 3 fg μL⁻¹ can be visually detected within 20 min with the naked eye. Additionally, the quantitative information can be easily obtained by using a spectrophotometer and smart phone, and the limit of detection (2.00 fg μL^-1, 63.7 aM) based on UV–vis absorbance is comparable with conventional PCR, however the assay time is about 2∼3 times shorter for the PPT-cPCR and the assay method is cost-effective. The strategy that combines PPT-based PCR and colorimetric analysis will open new horizons for point-of-care biosensor development.