Preparation of silica nanoparticles modified nanofibrillar cellulose and its metronidazole drug delivery properties

Abstract Nanofibrillar cellulose (NFC) was extracted by alkaline treatment of Yucca leaves followed by bleaching using H2O2, and then modified by silica nanoparticles (NPs). Obtained silica NPs modified NFC (SiO2 NPs-mNFC) was characterized using FT-IR, XRD, TGA, SEM, TEM and EDX analysis, and its metronidazole drug delivery properties were studied. However bare NFC showed higher loading of metronidazole than SiO2 NPs-mNFC, but NFC showed faster release of metronidazole than SiO2 NPs-mNFC. Release of metronidazole from NFC is not pH dependent, as 92.2% and 85.4% cumulative release percentage of metronidazole was released until 7.5 h, at both pH values of 4.5 and 7.4, respectively. However, SiO2 NPs-mNFC released the metronidazole very slowly, and was also pH sensitive, as cumulative release percentage of metronidazole were measured to be 53.3% at pH = 4.5, and 19.6% at pH = 7.4 after 48 h. Kinetic of the metronidazole release from SiO2 NPs-mNFC was studied by fitting the experimental data with well-known kinetic models, such as First order, Higuchi, Korsmeyer-Peppas, Hixson-Corwell and Baker-Lonsdale models. Results revealed that the metronidazole release is well fitted with Hixson–Crowell models at both pH values, confirming that the change in surface area of SiO2 NPs-mNFC during the process of dissolution has a significant effect on metronidazole release. Fickian diffusion of metronidazole at both pH was concluded by calculating n values of 0.3438 at pH = 7.4 and 0.4224 at pH = 4.5 by nonlinear fitting the release experimental data using Korsmeyer-Peppas model.