Facile fabrication of functional hydrogels consisting of pullulan and polydopamine fibers for drug delivery.

With the rapid development of biomedicine applications, more flexible and efficient fabrication strategies are required for drug delivery vehicles. Naturally resourced polymers have gained considerable attention for construction of drug carriers. Here, biocompatible hydrogel reservoir system (named PHG-PDA) based on pullulan and polydopamine (PDA) are designed and fabricated by one-pot incorporation of PDA fibers into pullulan hydrogel (PHG). The structure and performance of the PHG-PDAs can be nicely adjusted by regulating the content of PDA fibers in precursor hydrogel solutions. Crystal violet is used as a drug prototype and introduced into hydrogels via swelling-diffusion approach. We found that the drug loading process followed the pseudo-second-order model and Langmuir isotherm model, while the drug releasing process was pH-responsive, and the cumulative release reached 60.3% and 87% at pH 7.4 and 5.0, respectively. In vitro cytotoxicity studies on L929 cells demonstrated that our hydrogels were nontoxic even in a high concentration (3.4 mg/mL). In sum, these biocompatible PHG-PDAs with tunable physicochemical properties are promising systems for drug delivery.