Design, Synthesis, and Fabrication of Chitosan/Hydroxyapatite Composite Scaffold for Use as Bone Replacement Tissue by Sol-Gel Method

Injuries or bone defects are phenomena that are harmful to human health. In the field of bone scaffold tissue engineering, hydroxyapatite nanoparticles have been considered due to their high similarity to inorganic bone composition, but despite the similarity of chemical composition, the mechanical properties of synthetic hydroxyapatite (HA) are weak compared to bone. In this study, hydroxyapatite nanoparticles were synthesized by the sol-gel method. Then eight samples of composite scaffolds with chitosan (Chi) as biopolymer and different percentages of hydroxyapatite (0, 25, 50, and 75%) were prepared using a crosslinker of glutaraldehyde (GA) and sodium tripolyphosphate (TPP). To characterize the synthesized hydroxyapatite powder and scaffold samples, FTIR, FE-SEM, XRD, DTA-TG characterization tests, bioactivity analysis, and also strength test were performed. The results of the FESEM analysis show that hydroxyapatite particles with an average size of 48 nm have been synthesized by the sol-gel method. Also, FE-SEM images of scaffold samples show that as the amount of hydroxyapatite increases, the size of the pores decreases, and their distribution is uniform. FTIR spectroscopic analysis shows that both types of crosslinkers behave almost similarly and that the hydroxyapatite particles have established hydrogen bonds with the chitosan. Samples containing 75 wt.% of hydroxyapatite have the highest compressive strength and samples containing 50 wt.% of hydroxyapatite have the best behavior in terms of elongation. Scaffold samples were placed in simulated body fluid (SBF) for biological analysis for 1 week. FESEM images after removal of scaffolds from SBF solution show that the amount of calcium and phosphate ions adsorbed on scaffold samples containing 75 wt.% of hydroxyapatite is higher than other samples. One of the most important results of glutaraldehyde cross-linking with hydroxyapatite is that it controls the mechanical properties and adsorption rate without reducing the high biocompatibility of the composite. Also in this study, CHi-HA50%-TPP scaffolds exhibited the most promising physiochemical and biocompatible properties which can be used as an alternative regenerative material for bone tissue engineering.

Automated summary

In this study, hydroxyapatite nanoparticles were synthesized and incorporated with chitosan to prepare composite scaffold samples with varying hydroxyapatite content. The synthesized hydroxyapatite and scaffold samples were characterized using various analysis methods. The results showed that the mechanical properties and biocompatibility of the scaffold samples were closely related to the hydroxyapatite content.