Optofluidic devices combining optics and microfluidics have recently attracted attention for biomolecular analysis due to their high detection sensitivity. Here, we show a silicon chip with tubular microchannels buried inside the substrate featuring temperature gradient (∇T) along the microchannel. We set up an optical fluorescence system consisting of a power-modulated laser light source of 470 nm coupled to the microchannel serving as a light guide via optical fiber. Fluorescence was detected on the other side of the microchannel using a photomultiplier tube connected to an optical fiber via a fluorescein isothiocyanate filter. The PMT output was connected to a lock-in amplifier for signal processing. We performed a melting curve analysis of a short dsDNA - SYBR Green I complex with a known melting temperature (TM) in a flow-through configuration without gradient to verify the functionality of the proposed detection system. We then used the segmented flow configuration and measured the fluorescence amplitude of a droplet exposed to ∇T of ≈ 2.31 °C mm-1, determining the heat transfer time as ≈ 554 ms. The proposed platform can be used as a fast and cost-effective system for performing either MCA of dsDNAs or for measuring protein unfolding for drug-screening applications.

Central European Institute of Technology Brno University of Technology Purkynova 123 612 00 Brno Czech Republic

Department of Microelectronics Faculty of Electrical Engineering and Communication Brno University of Technology Technicka 3058 10 61600 Brno Czech Republic

Hong Kong University of Science and Technology Clear Water Bay Hong Kong P R China

Ministry of Education Key Laboratory of Micro and Nano Systems for Aerospace School of Mechanical Engineering Northwestern Polytechnical University 127 West Youyi Road Xi'an Shaanxi 710072 P R China

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An integrated microfluidic platform for nucleic acid testing

PCR Multiplexing Based on a Single Fluorescent Channel Using Dynamic Melting Curve Analysis