A forsterite-reinforced polypropylene fumarate/methoxy polyethylene glycol-hydrogel enriched with flavonoid nanoparticles enhances osteoconductivity

Abstract

Tissue engineering offers potential solutions for degenerative bone diseases. In the current study hesperetin (a flavonoid) was loaded in gliadin (a natural protein) NPs and used to enrich an injectable hydrogel of PPF–MPEG reinforced with Fs (a bioceramic) to enhance osteoconductivity. The PPF–MPEG hydrogel (4–6% w/v) containing 3–5% w/w Fs NPs was prepared. Then, the optimum hydrogel concentration was selected based on its properties like degradation, swelling, rheologic behavior, injectability, porosity, and biomineralization. Finally, Hst–GNPs (10, 20, and 40% w/v) were added to the optimized hydrogel. The MG-63 cells were utilized to conduct cell proliferation and attachment analysis, alkaline phosphatase assay, alizarin red staining, and osteogenic gene expression analysis. Hst–GNPs in the ratio of 1 : 3 (Hst 5 mg and GNPs 15 mg) showed an appropriate particle size (233.4 ± 3.6 nm), zeta potential (−13.5 ± 1.752 mV), EE% (97.98 ± 0.00%), and RE_8 h% (86.39 ± 0.10%) among other formulations. The 6% w/v PPF–MPEG hydrogel containing 3% w/w Fs showed appropriate injectability (17.41 ± 0.88 N), swellability, degradation, and mechanical properties. Moreover, the Fs NPs affected the degradation rate and swelling degree of the hydrogel; nevertheless, their overloading resulted in decreased Young's modulus and compressive strength of the hydrogel. The hydrogel containing 10% w/v Hst–GNPs showed the most significant rapid release among those containing other ratios. Also, significant enhancement was seen in mineralization, differentiation, and cell proliferation. In addition, higher expression of bone-specific genes, including collagen 1, osteocalcin, and osteopontin, was revealed in the cells treated with the PPF–MPEG/Fs/Hst–GNPs compared to the blank hydrogel.