Investigation of In Vitro Loading and Release Kinetics of Hydroxyapatite/Cellulose Biocomposites

Abstract

Cellulose nanocrystal (CNC) and hydroxyapatite (HAP) offer numerous advantages in drug delivery. A significant challenge encountered is the occurrence of burst release when these materials are used as drug carriers. This renders drugs ineffective when used at sites that require a sustained release. In this work, CNC and HAP composites were synthesized and used as drug carriers to investigate the release behavior of a model drug (curcumin). Two synthesis techniques were used where one material serves as the base material and the other as a modifier in varying concentrations. The formulated composites were characterized by Fourier-transform infrared spectroscopy (FTIR) and X-Ray powder Diffraction (XRD). The drug was loaded onto the composites for 22 hours. Composites with HAP as base material demonstrated successful loading of curcumin whereas composites with CNC as base material did not exhibit drug uptake. There were no significant differences (p > 0.05) in terms of drug uptake between the formulated composites and the control (HAP). The release properties of the composites were evaluated in vitro for 6 hours at acidic (pH ≈ 6.2) and basic (pH ≈ 7.4) conditions. The percentage drug release in acidic medium was found to be higher than basic medium. One-way ANOVA revealed that there was no difference in the means of the release data between the composites and the control group at acidic pH (p > 0.05). However, at basic condition, the release data of the composites and the control group showed significant differences (p < 0.05). Significant differences (p < 0.01) were observed for all composites across groups, indicating that changes in pH had a significant effect on the drug release. All composites and control at both pH (6.2 and 7.4) were best described by the Korsmeyer-Peppas model. Cell viability studies showed that modified composites inhibited cell growth at all time points during the drug release as compared to HAP only. This shows that the combination of HAP and CNC serves as a better drug delivery system than HAP only.