Carboxymethyl starch was modified by the incorporation of an azidophenyl group to prepare photoreactive starch, and characterized by Fourier transform infrared reflectance (FT-IR), proton nuclear magnetic resonance (1H-NMR), and ultraviolet (UV) spectroscopy. Photo-irradiation immobilized the Az-starch on a polystyrene plate and it was stably retained on the surface. The protein containing immobilized Az-starch was also immobilized on a stripe micropatterned plate. UV irradiation time and Az-starch concentration were used to alter the physical properties of Az-starch and consequently control the rate of epidermal growth factor (EGF) release. The Az-starch that released growth factor was not cytotoxic to 3T3-L1 fibroblast cells, and the immobilized EGF maintained its activity and induced cellular proliferation in vitro. These results suggest that Az-starch could be useful as a clinical synthetic material for medical applications. (c) 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013