Stabilization and Kinetics of an Adsorbed Protein Depends on the Poly(-isopropylacrylamide) Grafting Density.

The solubility transition at the lower critical solution temperature (LCST, 32 °C) of poly(-isopropylacrylamide) (PNIPAM) is widely used as a thermal switch to rapidly and reversibly capture and release proteins and cells. It is generally assumed that proteins adsorbed to PNIPAM above the LCST are unaffected by polymer interactions. Here we show that the folding stability of the enzyme phosphoglycerate kinase (PGK) is increased by interactions with end-grafted PNIPAM films above the LCST.