Water-induced surface reorganization of bioscaffolds composed of an amphiphilic hyperbranched polymer

Abstract

The ability to freely control the surface of bioscaffolds in a water environment is desirable to regulate cellular behaviors in vitro. Herein, we study the surface aggregation states of scaffold films composed of a multifunctional hyperbranched polymer (HBP) with perfluorohexylethyl, carboxy, and cyano groups that was prepared using a spin-coating method. Static contact angle measurements in conjunction with X-ray photoelectron spectroscopy revealed that perfluorohexylethyl groups were segregated at the surface of the HBP film in air, and these findings were more remarkable for the film treated with thermal annealing. Once the HBP film contacted water, HBP chains reorganized at the surface to minimize the free energy, resulting in the formation of a relatively hydrophilic surface. This surface reorganization was discernably faster and more remarkable for the non-annealed HBP film than for the annealed film. As fundamental characteristics of a cellular scaffold, protein adsorption, in addition to the initial adhesion and proliferation of fibroblasts, was examined using microscopy. The amount of fibronectin adsorbed depended on the presence of thermal annealing during the scaffold preparation process. A relatively larger amount of fibronectin adsorbed to the non-annealed HBP film promoted the initial adhesion and subsequent proliferation of fibroblasts.The aggregation states at the surface of spin-coated scaffold films composed of a multifunctional hyperbranched polymer (HBP) were characterized. While perfluorohexylethyl groups were segregated at the surface in air, the surface in water turned to be hydrophilic to minimize the free energy at the outermost region in the film. This surface reorganization was discernably faster and more remarkable for the non-annealed HBP film than for the annealed one. Fibronectin, which promoted the cellular behaviors, was more adsorbed onto the non-annealed HBP film.