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

Abstract

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) [PEG26‐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

Tailoring the Degradation Time of Polycationic PEG-Based Hydrogels toward Dynamic Cell Culture Matrices

“…The successful functionalization was determined by 1 H NMR spectroscopy (Figure S2A) by comparing the integrals of the PEG backbone signal at 3.72 ppm to the signal of the methyl groups of ABMP at 1.95 ppm. One has to note that the distribution of the initiation site is statistical, and hence also 2-fold, 3-fold, and 4-fold functionalized PEG building blocks are possible . However, the narrow and monomodal distribution of the SEC trace after block extension indicates that the resulting inhomogeneities can be neglected.…”

“…ABMP was synthesized as described before . Allylamine (3.59 mL, 1.1 equiv) was dissolved in dry dichloromethane (100 mL) and triethylamine (20 mL).…”

“…[PEG 26 -SH] 3 [PEG 26 -ABMP] was synthesized as described before . [PEG 26 -SH] 4 (2.0 g, 1 equiv), ABMP (83.13 mg, 1 equiv), and DMPA (10.34 mg, 0.1 equiv) were dissolved in chloroform (8 mL) and stirred for 2 min under UV irradiation.…”

“…[PEG 26 -SAc] 3 [PEG 26 -ABMP] was synthesized as described before . [PEG 26 -SH] 3 [PEG 26 -ABMP] (1.8 g, 1 equiv) was dissolved in dry dichloromethane (35 mL), and triethylamine (0.58 mL, 12 equiv) was added.…”

“…Since studies show that quaternary ammonium groups show the lowest electrostatic cell adhesion among amino functionalities, we herein demonstrate the synthesis of the novel degradable cross-linker N , N -(bisacryloxyethyl) amine (BAA) bearing a secondary amino functionality for improved cell adhesion. In a second approach, we introduce polycationic stickers based on poly­( N -(3-(dimethylamino)­propyl)­acrylamide) (PDMAPAam) by asymmetric block extension of [PEG-SH] 4 , which we recently established for polyampholytic poly­(dehydroalanine) (PDha) . The adsorption of the transforming growth factor β (TGF-β) into such polycationic hydrogels stimulated the ECM production of fibroblasts during the degradation of the underlying hydrogel.…”