Cellulose Nanofibers/SiO2 Nanocomposite: Preparation, Characterization and pH-Controlled Doxorubicin Delivery Properties

Cellulose nanofibers/SiO2 nanocomposite was prepared by extraction of cellulose nanofibers (CNFs) from Yucca leaves, followed by immobilization of SiO2 nanoparticles on the surface of cellulose nanofibers denoted as SiO2@CNFs. Prepared SiO2@CNFs nanocomposite was characterized using various techniques, including Fourier Transform Infra-Red (FT-IR), X-Ray Diffraction (XRD), Thermogravimetric analysis (TGA), scanning electron microscopy (SEM), Transmission electron microscopy (TEM) and Energy Dispersive Spectroscopy (EDS) analysis, and used as controlled drug delivery system for the release of doxorubicin, an anticancer drug. CNFs exhibited higher loading level of doxorubicin (79.82%) than SiO2@CNFs (72.67%), while CNFs exhibited rapid drug release, but SiO2@CNFs showed controlled drug release properties. Doxorubicin release from CNFs is not pH sensitive, as CNFs released high content of doxorubicin, 94.0% and 88.0% within 5-7 h, at both pH values of 4.5 and 7.4, respectively. However, the release of doxorubicin from SiO2@CNFs occurred slowly, and could be controlled by pH, as cumulative release percentage of doxorubicin from SiO2@CNFs were measured to be 73.5% at pH = 4.5, while 17.07% at pH = 7.4 after 48 h. Doxorubicin release kinetic was studied by fitting the experimental data with well-known kinetic models, including zero order, first order, Higuchi, Korsmeyer-Peppas, Hixson-Corwell, Weibull and Gompertz models. Results revealed that the doxorubicin release from SiO2@CNFs is well fitted with Higuchi and Hixson–Crowell models at pH = 4.5 and Hixson–Crowell model at pH = 7.4. Fitting the date using Korsmeyer-Peppas indicated the nonFickian diffusion of doxorubicin from SiO2@CNFs at pH = 4.5 by n values of 0.4755, and Fickian type diffusion at pH = 7.4 by n values of 0.3359.