Magnetic polyurethane-based electrospun scaffolds: a linkage between magnetically enhanced bioactivity with shape memory effect for smart wound healing application

In this study, different shape memory polyurethane (SMPU)-based electrospun nanofibers containing Fe3O4 magnetic nanoparticles (MNPs) were prepared. The shape-memory behavior of these scaffolds enables minimally invasive applications within biological systems, while their magnetic properties enhance the growth, proliferation, and differentiation of the bone cells. SMPU was synthesized via a two-step pre-polymerization method. The effects of MNPs on hydrogen bonding, crystallinity, thermal properties, hydrophilicity, water absorption, and mechanical and shape memory properties of SMPU were investigated. The results revealed that MNPs restricted the hydrogen bonds formation and promoted microphase separation in SMPU hard and soft segments. Moreover, a reduction in the degree of crystallinity of oft segments in the SMPU nanocomposites was observed by the addition of MNPs. Scanning electron microscopy was employed to determine the average diameters and size distributions of the SMPU nanofibers. In addition, the results showed that the prepared electrospun nanofibrous mats have adequate mechanical and shape memory properties for practical biomedical applications. Bioactivity studies indicated that the presence of MNPs could enhance the In-vitro cell cultivation of MG63 bone cells on the nanofibers. These results indicated that the prepared electrospun nanofibers could be utilized as a potential candidate for shape memory-assisted smart wound healing applications.

本研究制备了多种含四氧化三铁磁性纳米颗粒（Fe₃O₄ magnetic nanoparticles, MNPs）的形状记忆聚氨酯（shape memory polyurethane, SMPU）基静电纺纳米纤维。这类支架的形状记忆特性使其可在生物系统中实现微创应用，而其磁性能可促进骨细胞的生长、增殖与分化。SMPU通过两步预聚合法合成。研究了MNPs对SMPU的氢键作用、结晶度、热性能、亲水性、吸水率以及力学与形状记忆性能的影响。结果表明，MNPs会限制SMPU硬段与软段的氢键形成，并促进其微相分离。此外，添加MNPs后，SMPU纳米复合材料软段的结晶度有所降低。采用扫描电子显微镜（scanning electron microscopy, SEM）测定了SMPU纳米纤维的平均直径与尺寸分布。此外，结果显示，所制备的静电纺纳米纤维膜具备满足实际生物医学应用需求的力学与形状记忆性能。生物活性研究表明，MNPs的存在可提升MG63骨细胞在该纳米纤维上的体外细胞培养效果。上述结果表明，所制备的静电纺纳米纤维有望作为形状记忆辅助型智能伤口愈合应用的潜在候选材料。