Citric acid crosslinked biocompatible silk fibroin-mediated porous chitosan films for sustained drug release application

We prepared silk fibroin (SF)-mediated porous chitosan films using the ionic gelation approach. Citric acid was employed as an eco-friendly crosslinker and poly(ethylene glycol) (PEG) as a porogen. The prepared films were characterized for various physicochemical, mechanical and antibacterial properties, and subsequently loaded with gentamicin sulfate as a model drug. The water contact angle indicated that the pristine chitosan film was hydrophobic but became hydrophilic after the release of PEG. This could facilitate the uptake of the hydrophilic gentamicin sulfate. The infrared spectroscopy expressed strong intermolecular interactions across the amino groups of silk protein and the hydroxyl groups of the chitosan matrices. The XRD indicated molecular interaction between SF and chitosan caused a crystalline trend in the blend film. The thermal analysis revealed that the prepared films were stable up to 330ºC. The silk reinforcement significantly improved the tensile strength (from 25.53 ± 2.5–45.24 ± 4.5 MPa) and elongation at break (from 22.24 ± 2.20–36.12 ± 3.60%) with an appropriate swelling ratio. The prepared SF-mediated porous chitosan films exhibited broad-spectrum antibacterial activity, appropriate biocompatibility and desirable polar interaction with the gentamicin sulfate for controlled drug release applications.