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Abstract

Poly(N-isopropyl acrylamide) (PIPA Am) demonstrated a fully expanded chain conformation below 32°C and a collapsed, compact conformation at high temperatures. This unique temperature responsive polymer was grafted onto surfaces of commercial polystyrene dishes and used as temperature switches for creating hydrophilic surfaces below 32°C and hydrophobic surfaces above 32°C. Cells attachment and the growth of bovine endothelial cells and rat hepatocytes on PIPA Am-grafted surfaces at 37°C demonstrated similar behavior to the commercialized culture dishes. Both cell types were observed to detach from the PIPA Am-grafted surface simply by reducing the temperature below the polymer transition temperature (collapse). Cells recovered by this method maintained substrate adhesivity, growth, and secretion activities nearly identical to those found in primary cultured cells in contrast to the compromised function found in cultured cells damaged by trypsinization. These results provide strong evidence that PIPA Am-grafted surfaces, as thermal switches are very effective for reversing cell attachment and detachment without cell damage. Properties of cell culture surfaces can be readily transformed by this technique reversibly into hydrophilic and hydrophobic coatings of PIPA Am-grafted polymers. © 1993 John Wiley & Sons, Inc.