液态金属生物医学研究进展

Research progress on liquid metal in biomedicine

液态金属作为一种功能性材料已经广泛应用于电子、机械工程和能源等多个领域.低熔点的性质使液态金属保持金属性质的同时,具有室温流体的特性,这种特性成为了它最迷人的性质.液态金属还拥有许多其他优异的性质,如可变形、可功能化、导电导热及生物安全性,并在多种生物医学应用中拥有巨大潜力.本文首先介绍液态金属的基础结构与理化性质,如低熔点、表面自限制氧化等,这些性质为其应用奠定了基础.随后,本文从药物载体、肿瘤治疗、生物成像及医疗器械4个方面简要总结液态金属在生物医学领域的应用进展.最后,从提升液态金属纳米液滴尺寸均一性、深入研究其与生物系统和组织的相互作用、优化封端配体、基于液态金属的柔性可穿戴诊疗一体化医疗设备的发展及3D打印等领域,讨论了液态金属在生物医疗应用中未来的前景和发展方向.

Human health and biomedicine have always been the hot topic of broad interest,and researchers have been constantly developing materials with higher efficiency and biosafety to meet various needs in biomedical field.As a functional material,liquid metal has been widely used in many fields such as electronics,mechanical engineering,and energy.Recently,the potential of liquid metal in the biomedical field has been attracting more and more researchers.The crystal structure of solid gallium exhibits both covalent bonds and metal bonds,endowing it with unique properties.The strong covalent bonds exist in gallium dimers,which leads to a high boiling point of 2205℃,while the weak metal bonds exist between gallium dimers,resulting in a low melting point of 29.8℃.Gallium tends to form alloys with the majority of metals,and its melting point could be further reduced when mixed with indium and tin.With the decrease in size,liquid metal droplet exhibits a significant subcooling effect.When exposed to small amounts of oxygen,a self-limiting oxide layer immediately forms on the surface of liquid metal,protecting it from further oxidation.Based on these unique properties,liquid metal exhibits many advantages in biomedicine.The low melting point enables liquid metal deformable under external stimuli such as heat and freezing.Besides,the deformability of liquid metal makes it attain the ability of self-healing,which could automatically fill the defects caused by an external force.Furthermore,liquid metal can be functionalized by the modification with groups such as-SH,and the oxide layer on its surface enables the interaction with more groups.Heat can be generated when the large-sized liquid metal droplets are activated by an alternating magnetic field.And liquid metal magnetic fluid can be obtained when mixed with small-sized magnetic particles.There has been a lot of evidence that liquid metal has excellent biosafety.Liquid metal shows long-term biological safety and low toxicity to organisms,whether implanted or injected.With further research,many applications of liquid metal in biomedicine have been developed.A variety of drug molecules can be loaded on the surface of liquid metal,and the deformation caused by external stimulus can make liquid metal work as a switch to release drugs,to realize accurate and controllable release of drugs at the diseased site.Many properties of liquid metal like deformation,photothermal and magnetic heat can make liquid metal work well in tumor treatment.Recent studies have shown that liquid metals can work as contrast agents for various biological imaging,providing dynamic information in vivo.As a functional material,liquid metal has the properties of both metal and fluid,which shows great potential in the development of flexible wearable medical devices.Although the excellent properties of liquid metal make it show broad prospects in many biomedical fields,there are still many problems to be solved urgently.Researchers should further improve the size uniformity from the synthesis method,study the interaction between liquid metal nanoparticles and biological systems and tissues,and optimize the capping ligands,solve the problem that it is difficult to achieve high-precision 3D printing due to the high surface tension of liquid metal,and then develop more skin-friendly flexible wearable medical equipment with integrated diagnosis and treatment.