Adsorption and desorption behavior of natural and synthetic active compounds on hydroxyapatite-based nanocomposites

Abstract Nano-hydroxyapatite (nano-Hap) and different Hap-based nanocomposites (NCs) containing nanocarbons with different morphologies (functionalized multiwall carbon nanotubes - fMWCNT, graphene oxide - GO, and fullerene - Ful), and gelatin (Gel) were studied to highlight the modification of their adsorption and desorption properties. The obtained Hap-based NCs were characterized using powder X-ray diffraction, laser diffraction, transmission electron microscopy, and Fourier transform infrared spectroscopy. Moreover, ultraviolet–visible spectroscopy was used to investigate the adsorption and desorption properties of the obtained NCs. The adsorption experiments were performed with both ibuprofen (IBU, synthetic active substance) and anthocyanin (ANTO, natural active substance). The results revealed that the studied additives had little influence on improving the drug adsorption as compared to pure HAP. The adsorption energies were evaluated using density functional theory (DFT), which indicated that the interaction with GO is much stronger than the interaction with Ful, due to the formation of hydrogen bonds. The desorption experiments were carried out in simulated body fluid (SBF). fMWCNT and GO had a positive effect in the case of both natural and synthetic anti-inflammatory drugs, due to the morphology and the intermolecular interactions between the functional groups. The positive effect of Gel was observed in the adsorption studies of both substances, Gel increased the adsorption capacity of the NCs. The release profile of IBU was carried out using various mathematical models (zero-order, first-order, Higuchi, Hixon-Crowell, and Korsmeyer-Peppas).