Asymmetric Block Extension of Star-Shaped [PEG-SH] 4 - Towards Poly(dehydroalanine)-Functionalized PEG Hydrogels for Catch and Release of Charged Guest Molecules.

With the incorporation of polyampholytic segments into soft matter, hydrogels can serve as a reservoir for a variety of charged molecules which can be caught and released upon pH change. We herein demonstrate asymmetric block extension of star-shaped poly(ethylene glycol) [PEG 26 -SH] 4 using short segments of polyampholytic poly(dehydroalanine) (PDha) while maintaining the functional thiol end groups for network formation. For subsequent hydrogel synthesis with up to 10 wt.% PDha we exploited a straightforward and biocompatible photoinitiated thiol-ene click reaction. The investigation of the swelling properties of the hydrogel revealed a responsive behaviour towards ionic strength and variations in pH value. Moreover, the reversible adsorption of the model dyes methylene blue (MB) and acid orange 7 (AO7) was investigated by UV/Vis measurements and the procedure could be successfully transferred to the adsorption of the adhesion peptide RGDS resulting in an uptake of 1.5 wt% RGDS in regard to the dry weight of the hydrogel. This article is protected by copyright. All rights reserved.