Biomedical Application Of Multifunctional Metal Nanomaterials And Nanosafety

Cancer is an invisible killer threatening human health.So far,the clinical treatment of cancer is limited to surgery,radiotherapy and chemotherapy.Surgical resection is difficult to completely remove malignant cancer cells,and the residual cancer cells will lead to tumor recurrence and metastasis.The main reason why cancer is difficult to cure is the metastasis and uncontrollability of tumor cells.Furthermore,systemic chemotherapy and radiotherapy have serious side effects,limited therapeutic effect,multidrug resistance and long-term damage to the immune system.Therefore,early diagnosis,real-time monitoring and personalized treatment of cancer are the key to cure.Bacterial infection affects millions of people every year,and it is also a worldwide public health problem.At present,due to the dependence on antibiotics,multi-drug-resistant"super-bacteria"is continually appearing,and the efficacy decreases sharply.Metal nanomaterials have the characteristics of controllable size,surface charge,morphology,unique electrical、magnetic、optical and plasma,targeting ligands,surface easy modification and good biocompatibility.In addition,they have high near-infrared absorption and good photothermal conversion efficiency,so they can not only be used as drug carriers,but also have the ability of imaging and treatment,which can monitor the therapeutic effect in real time and achieve the integration of diagnosis and treatment of tumor.Because of its low dose,high effect and overcoming multidrug resistance,it can be used to resist drug-resistant bacterial infection.In the first part,a kind of biodegradable Bi₂S₃ nanoflowers was synthesized by hydrothermal method using biological macromolecule BSA.Bi₂S₃ nanoflowers had the characteristics of good biocompatibility,low toxicity,high X-ray attenuation coefficient,high near infrared absorption and high photothermal conversion efficiency,so they could be used for CT imaging and photothermal therapy;owing to characteristics of BSA,Bi₂S₃nanoflowers were biodegradable in normal physiological microenvironment.Therefore,Bi₂S₃nanoflowers were biosafety and have had simultaneous diagnosis and therapy.In the second part,inspired by“defect-improved catalytic activity”and“surface roughness enhanced bacteria capture,”we developed a defect-rich adhesive Mo S₂/r GO vertical heterostructure through one-step microwave-assisted hydrothermal method.It has been demonstrated experimentally and theoretically that the as-prepared Mo S₂/r GO VHS possesseed defect and irradiation dual-enhanced triple enzyme-like activities（oxidase,peroxidase,and catalase）for promoting free-radical generation,owing to much more active edge sites exposure;and the rough surface realized by VHS showed excellent bacterial trapping ability,and improveed the destructive ability of reactive oxygen species（ROS）through local topological interaction.As a result,excellent antibacterial effect on both drug-resistant Gram-negative and Gram-positive bacteria was confired by Mo S₂/r GO VHS.To sum up,this paper designed a simple,convenient and effective material synthesis method,prepared multi-functional and biosafe metal nanomaterials using the controllable size,morphology and unique physical and chemical properties of metal nanomaterials,and initially realized the photothermal therapy guided by computed tomography and the"three in one"enzyme like activity excellent bacterial capture ability and bactericidal ability of metal nanomaterials,providing a safe and feasible solution to treat tumor and drug-resistant bacterial infection.