Microchannel DNA sequencing matrices with a thermally controlled "viscosity switch"

Polymers and hydrogels that swell or shrink in response to environmental st imuli such as changes in temperature, pH, or ionic strength are of interest as switchable materials for applications in biotechnology, In this paper, we show that thermoresponsive polymers offer some particular advantages as entangled matrices for DNA sequencing by capillary and microchip electropho resis, Matrices based on conventional water-soluble polymers demand a compr omise in their design for microchannel electrophoresis: whereas highly enta ngled solutions of high molar mass polymers provide optimal sequencing perf ormance, their highly viscous solutions require application of high pressur es to be loaded into electrophoresis microchannels, Here, we demonstrate th e reproducible synthesis, precise characterization, and excellent DNA seque ncing performance of high molar mass, thermoresponsive polymer matrices tha t exhibit a reversible, temperature-controlled "viscosity switch" from high -viscosity solutions at 25 degreesC to low-viscosity, microphase-separated colloidal dispersions at a chosen, elevated temperature. The viscosity swit ch decouples matrix loading and sieving properties, enabling acceleration o f microchannel now by 3 orders of magnitude. DNA sequencing separations yie lding read lengths of 463 bases of contiguous sequence in 78 min with 97% b ase-calling accuracy can be achieved in these matrices, Switchable matrices will be particularly applicable to microfluidic devices with dynamic tempe rature control, which are likely to provide the next major leap in the effi ciency of high-throughput DNA analysis.