A study on drug delivery and release kinetics of polyethylene glycol-functionalized few-layer graphene (FLG) incorporated into a gelatin–chitosan bio-composite film

Abstract

This study develops a composite film by incorporating few-layer graphene (FLG) within a gelatin–chitosan polymer matrix for enhanced drug delivery. The FLG was functionalized in two steps to produce a secondary functionalized FLG (FLG–PEG), resulting in improved dispersion in water, as characterized using an optical microscope. Morphological analysis revealed that FLG–PEG nanosheets are well dispersed, resulting in a smoother, more uniform composite film with the polymer wrapping around them. The functionalized FLG was embedded in a polymeric matrix of chitosan and gelatin, and a bio-composite was prepared by solution casting. FTIR, TGA, and DSC analyses of the samples were conducted to confirm the successful functionalization of the FLG and the increased thermal stability of the composite. Mechanical properties were evaluated, and it was observed that tensile strength and elongation at break increased by 15.41% and 28.90%, respectively, with 0.25% FLG incorporation. Cytotoxicity and antimicrobial assays revealed no adverse cellular effects (95% cell viability) and demonstrated strong antimicrobial activity against both Gram-positive and Gram-negative bacteria, confirming broad-spectrum activity. Uromitexan (Mesna), a cytoprotective adjuvant used during chemotherapy, was incorporated to study its drug-release behavior. The results showed that FLG–PEG composites exhibited rapid and sustained drug release at pH levels of 4.5, 7.0, and 8.0. Mathematical modeling revealed that the drug release kinetics mainly followed the Korsmeyer–Peppas model, driven by both Fickian diffusion (at pH 4.5 and 8.0) and non-Fickian diffusion (at pH 7.0). These findings indicate predictable drug-release behavior of the functionalized composite, suitable for infection-free applications across diverse physiological and pathological environments.