Biocompatible Wound Dressings Based on Chemically Degradable Triblock Copolymer Hydrogels

Abstract

The synthesis of a series of thermo-responsive ABA triblock copolymers in which the outer A blocks comprise poly(2-hydroxypropyl methacrylate) and the central B block is poly(2-(methacryloyloxy)ethyl phosphorylcholine) is achieved using atom transfer radical polymerization. These novel triblock copolymers form thermo-reversible physical gels with critical gelation temperatures and mechanical properties that are highly dependent on the copolymer composition and concentration. TEM studies on dried dilute copolymer solutions indicate the presence of colloidal aggregates, which is consistent with micellar gel structures. This hypothesis is consistent with the observation that incorporating a central disulfide bond within the B block leads to thermo-responsive gels that can be efficiently degraded using mild reductants such as dithiothreitol (DTT) over time scales of minutes at 37 degrees C. Moreover, the rate of gel dissolution increases at higher DTT/disulfide molar ratios. Finally, these copolymer gels are shown to be highly biocompatible. Only a modest reduction in proliferation was observed for monolayers of primary human dermal fibroblasts, with no evidence for cytotoxicity. Moreover, when placed directly on 3D tissue-engineered skin, these gels had no significant effect on cell viability. Thus, we suggest that these thermo-responsive biodegradable copolymer gels may have potential applications as wound dressings.

Nanoscale detection of metal-labeled copolymers in patchy polymersomes

“…This is because the membrane forming PHPMA block has a relatively high molecular weight (38 kDa) and hence low lateral diffusion, as known for polymersomes. 14,13 Interestingly, in the present work we observed PMPC PHPMA/PEO PHPMA patterns that are more typical of bimodal decomposition (see Figure 3b). In our previous experiments, the copolymers were mixed in a 1:1 molar ratio in the solid state and then rehydrated in water.…”

Rheology of associative polymer solutions

“…Reduction of this bond leads to cleavage of the triblock into two diblocks and melted the gels. The same strategy was used by Madsen [50] for a different triblock copolymer.…”

Synthesis of temperature and pH-responsive crosslinked micelles from polypeptide-based graft copolymer

“…The TEM image of PGNH1 micelles clearly reveals the presence of spherical nanoparticles with a mean diameter of $130 nm at pH 8.0 and 60°C. For polymeric micelles, it has been established that diameters determined by DLS are typically larger (sometimes about 2-4 times) than those by TEM because the former reflects morphology in the dry state, while those determined by DLS reflect the dimension of both the swollen core and the stretched shell [50,51].…”