Improved in vivo stability of silicon-containing polyurethane by fluorocarbon side chain modulation of the surface structure.

As a class of widely used biomedical materials, polyurethanes suffer from their insufficient stability in vivo. Although the commercialized silicone-polyetherurethanes (SiPEUs) have demonstrated excellent biostability compared with polyetherurethanes (PEUs) for long-term implantation, the usage of polydimethylsiloxane (PDMS) inevitably decreased the mechanical properties and unexpected breaches were observed. In this study, we introduced a fluorinated diol (FDO) into SiPEU to modulate the molecular interactions and micro-separated morphology. The fluorinated silicon-containing polyurethane (FSiPEU) was achieved with desirable silicone- and fluorine-enriched surfaces and mechanical properties at a low silicon content. As evidenced by in vitro culture of macrophages and in vivo hematoxylin-eosin (H&E) staining, FSiPEU demonstrated a minimized inflammatory response. After implantation in mice for 6 months, the material was devoid of significant surface degradation and had the least chain cleavage of soft segments. The results indicate that FSiPEU could be promising candidates for long-term implantation considering the combination of biostability, biocompatibility and mechanical performances.

Bioactive 3D porous cobalt-doped alginate/waterborne polyurethane scaffolds with a coral reef-like rough surface for nerve tissue engineering application.

Nerve injuries in the central or peripheral nervous system threaten human health and hinder social development, and effectively repairing or regenerating nerve tissues remains a huge challenge. The rise of tissue engineering strategies has brought new light for this. Similar to the extracellular matrix, biomimetic three-dimensional (3D) porous scaffolds can provide biophysical and biochemical cues to guide cell behaviors and support tissue growth. Here, we prepared a hybrid cobalt-doped alginate/waterborne polyurethane 3D porous scaffold with nano-topology of a "coral reef-like" rough surface via two-step freeze-drying. The experimental results demonstrated that the "coral reef-like" rugged surface topology and bioactive cobalt dopant synergistically promote the neurite outgrowth and up-regulate the synaptophysin expression of neuron-like cells PC12 on the scaffold. Furthermore, the scaffold notably relieved the inflammatory response of microglial cells BV2 with the transformation from pro-inflammatory (M1) to anti-inflammatory (M2) phenotype. We believe that this 3D porous scaffold offers bright design inspiration for neural tissue engineering scaffolds and holds potential applications in nerve repair.