Design and characterization of a pH-responsive carboxylated cellulose nanofibril composite aerogel for enhanced drug delivery

Conventional drug delivery systems often face challenges such as low biocompatibility, and limited effectiveness; thus, developing sustainable, pH-responsive materials like carboxylated cellulose nanofibrils (CNF) can enhance drug delivery efficacy. In this study, carboxylated CNF was used as raw materials, acrylic acid (AA) was used as a pH-responsive monomer, and a pH-responsive CNF composite aerogel was constructed as a drug carrier using free radical polymerization and physical blending. The microstructure and physicochemical properties of the CNF composite aerogels before and after drug loading were analyzed using advanced technologies including Fourier-transform infrared (FTIR), thermogravimetric analysis (TGA), x-ray diffraction (XRD), elemental analysis, scanning electron microscopy (SEM), and pore size analysis. The introduction of graphene oxide (GO) modified and optimized the network structure of cellulose aerogels and increased the drug-loading capacity. The network structure formed by AA polymerization made the network structure of the CNF composite aerogel more compact and uniform and prolonged the drug-release time. The loading capacities of the CNF-GO-5-FU, CNF-AA-5-FU, and CNF-AA-GO-5-FU CNF composite aerogels for fluorouracil were 286.78, 275.35, and 312.64 mg/g, respectively. The release curve of the CNF composite aerogel demonstrated a pH response that conformed to the first-order kinetics, Higuchi, and Korsmyer–Peppas models. The sustained-release mechanism of the CNF composite aerogel followed the Fickian diffusion mechanism, highlighting the aerogel's strong biomedical application potential.