synthesis and characterization of self-healing composite hydrogel as bone tissue engineering scaffold

Bioprinting is transforming the field of tissue engineering (te). recent investigations focus on development of suitable inks to be used as carrier matrices for cells and biological molecules. utilizing these inks, live cells can be loaded into a biomaterial and 3d-printed into precisely engineered scaffolds to be used for tissue reconstruction purposes. as joint replacement orthopaedic surgeries are prevalent and bone is one of the most substituted tissues in the biomedical field, designing 3d-printable bioactive materials for bone te is of great significance. although these scaffolds should be biodegradable to accommodate the new bone growth, they require to withstand mechanical loads during the formation of the new biological tissue. therefore, self-healing capability is considered as a desirable property for these platforms. the aim of the current research was to develop a novel self-healing and 3d printable composite hydrogel ink to be used in bone tissue engineering. to facilitate bone regeneration, 45s5 bioactive glass (bg) and dual crosslinking were used in the formulation of this hydrogel. the hydrogel was synthesized using a mixture of n-carboxyethyl chitosan (cec), hyaluronic acid-aldehyde (ha-ald) and adipic acid dihydrazide (adh), blended with different quantities of alginate (2%, 5%, and 10%) (all in wt%) and (0, 10%) bg. the physicochemical study of the specimens required the use of several different methodologies, such as scanning electron microscopy (sem), x-ray diffraction (xrd), energy-dispersive x-ray spectroscopy (eds), and fourier transform infrared spectroscopy (ftir). in addition, rheology evaluations were carried out to determine the values of storage (g') and loss (g'') moduli, and the viscosity rate. bioactivity evaluation in simulated bodily fluid showed that after 3 days of immersion, hydroxyapatite (ha) particles precipitated on hydrogels containing bg. as the sbf immersion time increased up to 14 days, a surge in the amount of deposited ha was observed. furthermore, it was observed that all specimens exhibited self-healing property at the strains of 1 and 500%, each performed at 200 s intervals. however, among the specimens, the bg-free hydrogel demonstrated the greatest values of g' and g'' in all oscillation tests, as well as the highest rate of viscosity. cytotoxicity investigation via mtt was performed on mg63 cell lines. based on the results, the composite hydrogel demonstrated higher cell viability than the bg-free one at all incubation times. after an incubation period of three days, this sample had the maximum cell viability (95 1.02%). after 24 hours of culture, all samples demonstrated suitable cellular adhesion. the results of this study confirm the potential of the developed self-healing composite hydrogel to be used in bone regenerative medicine applications.