Synthesis and evaluation of cytotoxicity of hybrid hydrogel based on chitosan and Ph.ZnO@HAP nanocomposite

In this study, phenolic compounds-coated ZnO@HAP nanocomposite (Ph.ZnO@HAP) was synthesized and used to improve the physical and chemical properties of chitosan hydrogel for biological application. At first, the phenolic compounds were extracted from walnut green hulls. The synthesis of Ph.ZnO@HAP nanocomposite was performed with the assistance of extracted phenols using a hydrothermal method. Chitosan hydrogel was also prepared using NaHCO3 at 37°C. Hybrid hydrogels based on chitosan and Ph.ZnO@HAP nanocomposite were prepared in a similar way and then characterized by fourier-transform infrared spectroscopy (FTIR) and field emission scanning electron microscopy (FESEM). The antioxidant property, cytotoxicity, and osteogenesis of hybrid hydrogels were measured using DPPH radical scavenging method, MTT, and alkaline phosphatase enzyme assay, respectively. The FTIR spectra, FESEM images, EDX spectrum, and Zeta potential data showed that Ph.ZnO@HAP nanocomposites synthesized successfully with rod-like morphology, phenolic compounds coated on the surface and a negative particle surface charge. The results of DPPH experiment showed that the antioxidant property of the nanocomposite material increased in a concentration-dependent manner. The FESEM images of chitosan hybrid hydrogels with different concentrations of embedded Ph.ZnO@HAP nanocomposite showed that hybrid hydrogels have a more uniform porous structure, compared to the chitosan hydrogel. Moreover, by an increase in the nanocomposite concentration in the structure of hybrid hydrogels, the antioxidant property augmented. The results of the biological studies showed that the cytotoxicity of hybrid hydrogels on osteoblast-like cells (Saos-2) is lower than that of chitosan hydrogel. Also, hybrid hydrogels showed the higher potential in induction of osteogenesis than chitosan hydrogels.