Near-Infrared Responsive Droplet for Digital PCR

Digital PCR (dPCR) surpasses the performance of earlier PCR formats because of highly precise, absolute quantification and other unique merits. A simple thermocycling approach and durable microcarrier are of great value for dPCR advancement and application. Herein, a near-infrared (NIR) controlled thermocycling approach by embedding magnetic graphene oxide (GO) composite into the agarose microcarriers is developed. The core-shell composite is constructed by sequentially encapsulating GO and silica outside the magnetic nanocores. Benefiting from these additives, the resultant composite agarose gains appealing features as light-driven temperature changing, switchable gel-sol phase transforming, biocompatibility, and magnetic traction. By further emulsifying into droplets via the microfluidics method, the influence of typical parameters including material loading amount, laser intensity, and droplet diameter at various ranges is investigated for assembling microcarriers with different responsiveness. Then a paradigm of the NIR program can be easily tailored for PCR thermocycling. Finally, the feasibility of the approach is verified by detecting statistically diluted Klebsiella pneumoniae DNA samples, from 0.1 to 2 copies per drop. It is anticipated that this method has promising prospects for dPCR-based and other temperature-controlled applications.