Nano-scale physical surface coating of temperature-responsive polymers for cell sheet fabrication

This study focused on the simple fabrication method of temperature-responsive cell culture surfaces by physical polymer coating. We synthesized diblock copolymers of poly(butyl methacrylate)-b-poly(N-isopropylacrylamide) (PBMA-b-PIPAAm) with various thermoresponsive PIPAAm chain length. Polymers were dissolved in mixed solvent of acetonitrile/N, N-dimethylformamide (5/1 in v/v), and the solution was deposited on the surface of commercial cell culture substrates using a spin coater. Chemically connected hydrophobic PBMA significantly enhanced physical absorption to target material surfaces and resulted in introducing thermoresponsive property to solid surfaces. To investigate temperature-dependent cellular behavior, bovine carotid artery endothelial cells were seeded on polymer-coated surfaces and cultured at 37 °C. Cells adhered and proliferated on temperature-responsive surface at 37 °C, while the efficiency of adhesion and proliferation became lower with increasing PIPAAm chain length. On the other hand, longer PIPAAm chains significantly promoted cell detachment from the surfaces by reducing temperature to 20 °C. Consequently, confluently cultured cells were successfully harvested as a single cell monolayer with maintaining cell-cell junctions and extracellular matrix proteins with simple low temperature treatment by choosing the adequate PIPAAm chain length of block copolymer.