Ultrafast plasmonic and real-time label-free polymerase chain reaction

There is a growing focus to adapt Polymerase Chain Reaction (PCR) to point-of-care (POC) testing to provide for a low-cost, rapid and reliable diagnostic instrument. Many studies proposed the integration of microfluidics with fluorophore-assisted or electrochemical amplicon detection methods to introduce a real-time miniature device for POC applications. However, their practicality in POC testing is limited due to their complex microfabrication, high cost, and intrinsic challenges due to their intercalation and hybridization-based detection. In this paper, we present a purely optical methodology without the addition of non-PCR reagents (electroactive or fluorogenic DNA intercalators) to enhance the reliability in quantitative PCR measurement of DNA yield. The determination of PCR results and DNA amplicon quantification are realized by monitoring transmitted power of a 260nm LED in PCR reaction at every thermal cycle. The least-square fits to transmission data demonstrate distinctive features to classify positive vs. negative PCRs and to quantify amplified products. This real-time UV monitoring system was combined with a VCSEL-based plasmonic thermocycler to accomplish fast amplification and detection in a simple and small-scaled footprint applicable for POC diagnostics.