Dynamic in situ chromosome immobilisation and DNA extraction using localized poly(N-isopropylacrylamide) phase transition

Abstract

A method of in situ chromosome immobilisation and DNA extraction in a microfluidic polymer chip was presented. Light-induced local heating was used to induce poly(N-isopropylacrylamide) phase transition in order to create a hydrogel and embed a single chromosome such that it was immobilised. This was achieved with the use of a near-infrared laser focused on an absorption layer integrated in the polymer chip in close proximity to the microchannel. It was possible to proceed to DNA extraction while holding on the chromosome at an arbitrary location by introducing protease K into the microchannel.

Optothermally actuated capillary burst valve

“…10 At lower power, the temperature of the solution in the microfluidic channel can be evaporated. At even lower power, we have also shown that the temperature increase can be adjusted to induce a phase transition of a thermally actuated hydrogel at ∼30 • C. 18 Since increasing the temperature to 60 • C is sufficient to induce a bursting pressure change larger than the chip-to-chip variation at room temperature, we hypothesize that the power of the actuating laser can be adjusted to yield a temperature rise sufficient to burst the valves (Figure 2) without inducing boiling of the solution or even denaturating proteins. To achieve bursting at the onset of the laser, we first apply a pressure across the valve that is just below the bursting pressure at room temperature.…”

Flow manipulation and cell immobilization for biochemical applications using thermally responsive fluids

“…15,16 Fiddes et al 14 demonstrated the use of hydrogels to transport immobilized biomolecules in a digital microfluidic system. While the design of Krishnan and Erickson is highly flexible, it requires the use of an optical system and absorption layer to generate a geometric pattern to redirect flow.…”

“…The sequence of the heater activation and deactivation in order to immobilize the cell and exchange the fluid is outlined in the supplementary material. 21 Eriksen et al 15 demonstrated the diffusion of protease K in the porous hydrogel matrix, 19 and it was therefore expected that DAPI fluorescent stain (molecular weight of 350 kDa, Ref. 20) would also diffuse.…”