Preparation of hyperbranched polystyrene-g-poly(N-isopropylacrylamide) copolymers and its application to novel thermo-responsive cell culture dishes

•Copolymers of hyperbranched polystyrene and poly(N-isopropylacrylamide) (HBPSt-g-PNIPAM) have been successfully synthesized.•The structure of HBPSt-g-PNIPAM is flexibly tunable by changing reaction conditions.•Thermo-responsive cell culture dishes can be easily prepared by casting HBPSt-g-PNIPAM on commercial polystyrene dishes.•The prepared thermo-responsive dishes demonstrate promising results in fabricating cell sheets of mouse 3T3 fibroblast cells.

This paper describes the preparation of hyperbranched polystyrene-g-poly(N-isopropylacrylamide) (HBPSt-g-PNIPAM) and its application as a novel thermo-responsive material for cell sheet preparation. HBPSt-g-PNIPAM was synthesized by grafting PNIPAM from the termini of HBPSt via reversible addition fragmentation transfer polymerization. The resulting HBPSt-g-PNIPAM was cast from a solution onto a commercial polystyrene-based dish (PS-dish) to make a thermo-responsive surface for cell cultivation (P4/PS-dish). Mouse 3T3 fibroblast cells were seeded on the P4/PS-dish with 2.5-3.5 μg/cm2 of PNIPAM and cultured at 37 °C for four days to achieve high confluency. Fairly large cell sheets were successfully collected by cooling the dish to 20 °C. The current material avoids the use of electron beam polymerization, which requires complicated equipment, for fabricating a thermo-responsive surface because PNIPAM is immobilized by the affinity between the hyperbranched polystyrene segment and the PS-dish.

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