Development of metformin chain extended polyurethane elastomers as bone regenerative films

In this study, novel elastomeric biodegradable bone regenerative films were developed from metformin (Met) and polyurethane (PU). Metformin was selected due to its osteogenic properties and proper chemical structure to react with PU prepolymer. Metformin was integrated into PU macromolecular structure as chain extender after the synthesis of PU prepolymer via condensation polymerization of polycaprolactone diol and hexamethylene diisocyanate. Chemical, thermal, viscoelastic properties of PU-Met films where characterized and discussed in terms of structure-property relationships. PU-Met films had Tg value around -45 °C and showed superior viscoelastic properties under 1 Hz and 10 Hz tensile oscillation frequencies during dynamic mechanical analysis. On the 21st day of biodegradation studies, PU-Met films degraded 2.3 ± 0.1% and 37.8 ± 4.2% in oxidative and enzymatic media, respectively. Cell-material interactions of elastomeric films were investigated by proliferation (MTT assay), alkaline phosphatase activity (ALP), calcium depositions (Alizarin Red Quantification) and morphological evaluations (SEM). Presence of metformin in PU formulation increased MC3T3-E1 attachment, proliferation and calcium deposition.