Graphene oxide/nano-hydroxyapatite (GO/nHAP) composites were synthesized by simultaneous titration method. The GO powder was uniformly dispersed ultrasonically in a solution containing Ca(NO₃)₂. It was co-titrated with (NH₄)₂HPO₄, during which NH₃·H₂O was used to maintain pH of about 10. Transmission electron microscopy (TEM) showed that HAP had a drusy acicular crystal structure with 100–200 nm length in the composite. The Ca²⁺ ions were attracted by the negatively charged oxygen functional groups present on GO sheets. They also oriented the growth of hydroxyapatite preferentially along (112) plane, which was also consistent with X-ray diffractometry (XRD) results. According to X-ray photoelectron spectroscopic (XPS) results, the peak intensities of the C–O and C–C groups increased in the GO/nHAP composite. However, the number of –COO– and C–O–C groups was reduced as well as the position of peaks shifted due to electrostatic interactions. These results were also corroborated with Fourier transform infrared spectroscopy (FTIR). MTT assay indicated that GO/nHAP composites had a significant effect on proliferation of 293T cells and good biomimetic mineralization as shown by in vitro bioactivity assays. EDS spectroscopy confirmed that the Ca/P ratio in calcium phosphate deposits was 1.62, which was close to the ratio of 1.64 in natural bone. The biological performance of GO/nHAP composite proved it to be a promising candidate for bone regeneration and implantation.

A novel IPN hydrogel scaffold is prepared by freeze-drying method, in which konjac galactomannan (KGM) and gelatin are physically crosslinked respectively. This scaffold is thermostable, and the structure of this scaffold is analysed by scanning electron microscope, Fourier transform infrared spectrum, and X-ray diffraction method. The FT-IR results show that hydrogen bonds are formed between KGM and gelatin molecules, which hinder the formation of their respective crosslinking. This is consistent with the XRD results that the crystallinity gets lower in the IPN gels compared with pure gelatin and KGM gels. The morphologies of freezedried hydrogels are observed by SEM and the mechanical properties of the scaffolds are tested to analyse the relationship between the structures and properties. Although this novel IPN hydrogel is physical gel, it shows rubber-like performance as chemical gels. And it is nontoxic, so it can be used as the scaffold for cartilage tissue engineering that embedded in human bodies.