Comparative evaluation of polyurethane scaffolds synthesized from fully and partially hydrolyzed PVA for bone tissue engineering

Abstract

In this study, two polyurethane scaffolds were synthesized using fully hydrolyzed polyvinyl alcohol (PVA-FH) and partially hydrolyzed polyvinyl alcohol (PVA-PH) as precursors, with hexamethylene diisocyanate (HDI) as a crosslinking agent. The influence of the polymer’s degree of hydrolysis on the physicochemical, thermal, morphological, and biological properties of the resulting materials was thoroughly evaluated. Fourier-transform infrared spectroscopy (FTIR) confirmed the formation of urethane linkages, with a higher crosslinking degree observed in PVA-FH-based scaffolds due to a greater availability of hydroxyl groups. However, thermogravimetric analysis revealed enhanced thermal stability in PVA-PH-PU scaffolds, associated with more effective microphase separation and restricted chain mobility. Swelling and degradation studies showed that PVA-FH-PU scaffolds absorbed more water and degraded faster, while PVA-PH-PU maintained better structural integrity over time and showed higher mineralization. Porosity measurements using both bulk density and mercury intrusion porosimetry indicated similar overall porosity, in the range of 30 to 40 %. Both materials were non-cytotoxic, as demonstrated by indirect contact assays, but showed limited initial cell colonization. Collagen coating significantly improved cell adhesion, especially for PVA-FH-PU scaffolds, making them promising candidates for bone tissue engineering applications.