Recycled Polyurethane (rPU)-Block-Hydroxybutyl-Terminated Poly(dimethylsiloxane) (hbPDMS) (rPU-b-hbPDMS) Copolymer Nanocomposites for Osteoblast Cell Regeneration

The prospect of developing a polymer with mechanical properties close to the bone tissues and having good biodegradation and biocompatibility makes polyurethane (PU) a promising material for bone tissue regeneration. Here, nanocomposites were developed using postconsumer discarded polyethylene terephthalate (PET) with selectively functionalized nanofillers to prepare porous scaffolds for bone tissue regeneration. This approach motivates the sustainable recycling and circular economy aspects associated with postconsumer discarded PET waste. PET was glycolyzed with ethylene glycol through transesterification using zinc acetate as a catalyst to produce bis(2-hydroxyethyl) terephthalate (BHET). Then, BHET was reacted with 1,6-hexamethylene diisocyanate (HMDI) to produce an NCO-terminated prepolymer of PU, which was then copolymerized with hydroxybutyl-terminated poly(dimethylsiloxane) (hbPDMS) using diethylenetriamine as a chain extender to impart adequate flexibility to the porous scaffolds. Studies on the U2OS osteoblast cell line showed adequate in vitro proliferations as 94 and 98% in 6 and 14 d, respectively. Hemolytic analysis shows that nanocomposites consisting of a lower loading of nanocrystals (≤2 wt %) are good for short-run bone tissue regeneration (up to 60 days), whereas a higher loading (5 wt %) is better for long-run bone tissue regeneration (60–90 days). Nanocomposites exhibit excellent mechanical, morphological, and biological properties and, thus, are potential candidates for proliferation of U2OS cells.