Preparation and characterization of alginate-b-PLA hydrogels
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Alginate is a widely used biomaterial for a variety of biomedical applications ranging from drug delivery to cell transplantation. The unique polysaccharide backbone endows the material with a number of useful properties such as hydrophilicity, biocompatibility, and gelation ability. Despite these advantages, one limitation for alginate is the lack of a tunable degradation rate, and its gels may only partially degrade and implants are not fully cleared from the body long after their purpose is fulfilled. To further extend the utility of this biomaterial, we hypothesized that by creating a polymer chimera between polylactic acid (PLA) and alginate we can integrate tunable degradation properties into alginate hydrogels. The alginate-b-PLA diblock copolymers were synthesized by utilizing an inverse electron demand Diels-Alder reaction, and were then fabricated into hydrogels using two approaches: doping with low viscosity alginate (LWA) and direct gelation. These hydrogel chimeras exhibited degradation rates that could be tuned from days to weeks. Morphologically, the combination of different domain sizes of alginate and PLA contributed to different microstructures within the hydrogel matrix that contributes to its degradability. Drug release was not impacted by matrix degradation rate, as four different encapsulated payloads of variable hydrophobicity and molecular weight were encapsulated with the chimeric hydrogels showed comparable release rates to non-degradable alginates. These new degradable alginates could have future utility as degradable drug-eluting implants.