Self-Assembly of Partially Alkylated Dextran-graft-poly(2-dimethylamino)ethyl methacrylate Copolymer Facilitating Hydrophobic/Hydrophilic Drug Delivery and Improving Conetwork Hydrogel Properties

Key issues of injectable hydrogels are incapability of loading hydrophobic drugs due to insolubility of drugs in aqueous prepolymer solution as well as in hydrogel matrix, and high water swelling, which leads to poor mechanical and bioadhesive properties. Herein, we report that self-assembly of partially long-chain alkylated dextran- graft-poly(2-dimethylamino)ethyl methacrylate copolymer in aqueous solution could encapsulate pyrene, a hydrophobic probe, griseofulvin, a hydrophobic antifungal drug, and ornidazole, a hydrophilic antibiotic. Addition of activated chloride terminated poly(ethylene glycol) (PEG) into the guest molecules loaded copolymer solution produced an injectable dextran- graft-poly(2-dimethylamino)ethyl methacrylate-linked-PEG conetwork hydrogel. The alkylated hydrogels exhibited zero order release kinetics and were mechanically tough (50-54 kPa storage modulus) and bioadhesive (8-9 kPa). The roles of alkyl chains and dextran on the drug loading-release behavior, degradation behavior, gelation time, and the mechanical property of the hydrogels have been studied in details. Additionally, DNA hybrid composite hydrogel was formed owing to the cationic nature of the prepolymer solution and the hydrogel. Controlled alkylation of a prepolymer thus highlights the potential to induce and enhance the hydrogel property.