Biomimetic hydrogels based on L-Dopa conjugated gelatin as pH-responsive drug carriers and antimicrobial agents

Biomimetic hydrogels which possess good biocompatibility, high degradability, and low toxicity as well as good antibacterial activity against various bacteria would potentially be promising for biomaterial applications, such as wound healing, tissue engineering, and payload delivery systems. Herein, we report the synthesis and hydrogelation of L-Dopa conjugated (GPLD) polypeptides via a versatile strategy including enzymatic cross-linking or coordinated/oxidized cross-linking with Fe³⁺ ions and demonstrated the feasibility of loading cancer drug and metal NPs in hydrogel matrix. The drug-loaded hydrogel was simply prepared via coordinated/oxidized cross-linking by Fe³⁺ and H₂O₂ within short gelation time. Doxorubicin (DOX) was encapsulated in the hydrogel network through the formation of metal-DOX/catechol complexes. The catechol groups acted not only as the complexing depots for DOX encapsulation but also as cross-linking depots for hydrogel formation. The mechanical strength, swelling ratio, and degradability behavior could be tuned by varying Fe³⁺/H₂O₂ or enzyme/H₂O₂ concentration. The as-prepared hydrogel exhibited excellent pH-responsive drug release behavior and the ability to effectively kill cancer cells by pH-triggered release of DOX. We also demonstrated that the enzymatically cross-linked hydrogels loaded with metal nanoparticles (NPs) exhibiting excellent antimicrobial activities. This multifunctional hydrogel is promising for drug delivery and antimicrobial applications.