In the current study, we introduced a new water‐soluble polyphosphazene containing hydroxyl groups, poly(propyleneglycol)phosphazene (PPGP). The PPGP is converted to PPGP‐TiO2 cross‐linked polymer via hydrothermal reaction with Ti(OBu)4. The properties of the obtained polymers were assessed by 1H‐NMR, 31P‐NMR, Fourier transform infrared spectroscopy (FTIR) and X‐ray diffraction (XRD) spectroscopic methods, thermal techniques (DSC‐TGA), FESEM–EDX investigations, cyclic voltammetry (CV) and Zeta potential measurements. In order to predict PPGP‐TiO2 cross‐linked polymer structure and obtain HOMO–LUMO maps and COMSO sigma profile, quantum calculations were used by DMol3 module based on Dispersion‐corrected density functional theory (DFT‐D) in Materials Studio Software2017. As a common bone substitute material, hydroxyapatite (HAp) was prepared using a modified method and closely characterized by appropriate analysis. The PPGP cytotoxicity was examined using C2C12 and L929 cell lines and Escherichia coli. The C2C12 differentiation using PPGP (as media supplement) was quantified by alkaline phosphatase activity assay. The biocompatibility of PPGP‐TiO2 was compared with HAp using mentioned cell lines and acute inflammatory testing. The results demonstrated that cell proliferation and osteoblastic differentiation increased in presence of PPGP. Both in vitro and in vivo evidence indicated that the novel scaffold had significant viability, exhibiting notable adaptability with its surrounding living tissue.

The present study aimed to synthesis a proper scaffold consisting of hydroxylated polyphosphazene and polycaprolactone (PCL), focusing on its potential use in tissue engineering applications. The first grafting of PCL to poly(propylene glycol)phosphazene (PPGP) was performed via ROP of ε-caprolactone, whereas PPGP act as a multisite macroinitiator. The prepared poly(propylene glycol phosphazene)-graft-polycaprolactone (PPGP-g-PCL) were evaluated by essential tests, including NMR, FTIR, FESEM-EDS, TGA, DSC and contact angle measurement. The quantum calculations were performed to investigate molecular geometry and its energy, and HOMO and LUMO of PPGP-g-PCL in Materials Studio2017. MD simulations were applied to describe the interaction of the polymer on phospholipid membrane (POPC128b) in Material Studio2017. The C2C12 and L929 cells were used to probe the cell–surface interactions on synthetic polymers surfaces. Cells adhesion and proliferation onto scaffolds were evaluated using FESEM and MTT assay. In vitro analysis indicated enhanced cell adhesion, high proliferation rate, and excellent viability on scaffolds for both cell types. The polymer was further tested via intraperitoneal implantation in mice that showed no evidence of adverse inflammation and necrosis at the site of the scaffold implantation; in return, osteogenesis, new-formed bone and in vivo degradation of the scaffold were observed. Herein, in vitro and in vivo assessments confirm PPGP-g-PCL, as an appropriate scaffold for tissue engineering applications.

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