Poly (N-isopropylacrylamide) (pNIPAAm), a thermo-responsive polymer that exhibits a lower critical solution temperature (LCST) of 32 °C in water has found an extensive use in tissue engineering and bioengineering applications in general. Since it is soluble in water, one of the main challenges that limit its applications in an aqueous environment is the tedious and expensive electron beam or plasma based procedures to retain it on a substrate. In this study, we report the use of various types of organo-silanes containing different functional groups to form siloxane networks for immobilizing pNIPAAm onto hydroxylated substrates in a simple two-step approach: spin coating followed by thermal curing. Substrates utilizing those organosilanes resulted in a stable film that exhibited thermo-responsive behaviors with transition temperatures (hydrophobic to hydrophilic) of 31 - 36 °C and rapid cell sheet detachment (in 100 – 300 s) of mouse fibroblast NIH 3T3 cells. In addition, the thermo-responsive behavior (i.e., the transition temperature) can be tuned by varying the ratio of organosilane/pNIPAAm blend and/or the curing time. This study illustrates the simplicity and versatility of the approach, which could broaden the usage of pNIPAAm and other polymers (e.g., conducting polymers for energy harvesting and electronic applications) that need to be retained on a hydroxylated surface.

Simple approach for surface immobilization of poly(N-isopropylacrylamide) using organosilane networks

251st National Meeting (2016)

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