Photoresponsive Delivery Microcarriers for Tissue Defects Repair

Intelligent responsive microcarriers have emerged as a promising class of biomaterials for therapeutic delivery and tissue regeneration, since they can respond to external stimuli and release the loaded drugs in an active manner. Among various available stimuli, near-infrared (NIR) light is particularly attractive because it can penetrate biotic tissues with sufficient intensity and minimal damage. In this work, a kind of photoresponsive delivery microcarriers (PDMs) is developed using microfluidics. The microcarriers consist of NIR-absorbing graphene oxide, thermosensitive poly(N-isopropylacrylamide), and biocompatible gelatin methacrylate. Under NIR light, the PDMs exhibit an evident volume shrinkage and effectively trigger the drug release. After the NIR light is switched off, the shrunken microcarriers return to their original size. This reversible process can be stably repeated for many cycles. An in vitro experiment demonstrates that the NIR-radiated PDMs can actively release vascular endothelial growth factors and improve the tube formation of human umbilical vein endothelial cells. The results from the in vivo experiment also show an obvious photothermal effect and superior therapeutic efficacy of these PDMs in a rat model of tissue defects. These features make the PDMs an excellent drug delivery system and represent a great potential for clinical applications in tissue repair.

智能响应性微载体作为一类有前景的生物材料，已应用于治疗性给药和组织再生，因为它们能够对外界刺激做出响应，并以主动的方式释放所负载的药物。在各种可用的刺激中，近红外（NIR）光特别具有吸引力，因为它能够以足够的强度穿透生物组织且损伤极小。在这项工作中，利用微流控技术开发了一种光响应性给药微载体（PDMs）。这些微载体由吸收近红外光的氧化石墨烯、热敏性聚（N - 异丙基丙烯酰胺）以及生物相容性甲基丙烯酸明胶组成。在近红外光照射下，PDMs呈现出明显的体积收缩，并有效地触发药物释放。关闭近红外光后，收缩的微载体恢复到其原始大小。这种可逆过程能够稳定地重复多次。一项体外实验表明，经近红外光照射的PDMs能够主动释放血管内皮生长因子，并促进人脐静脉内皮细胞的管腔形成。体内实验的结果也显示，在组织缺损的大鼠模型中，这些PDMs具有明显的光热效应和优异的治疗效果。这些特性使PDMs成为一种出色的药物递送系统，并在组织修复的临床应用中具有巨大潜力。