The Preparation And Application Of Functionalized Polydopamine Micro/Nano Motors

Micro/nano motors can convert a variety of energies into mechanical motion.There are different kinds of micro/nano motors which can be propelled by chemical reaction,biological designs,magnetic field,light and electric field,etc.The various structures of the micro/nano motors are being developed for different applications,such as microtubes,nanorods,Janus spheres,spirals,etc.In recent years,with the development of the research of micro/nano motors,micro/nano motors have been applied in environmental restoration,drug delivery and nanoscale manufacturing.However,the materials of micro/nano motors often have some disadvantages,such as biological toxicity,degradation,resistant and poor biocompatibility.Therefore,one of the development of micro/nano motors is to find more environmentally friendly materials with low toxicity,good degradation and biocompatibility.In this thesis,two kinds of novel micro/nano motors were fabricated with functionalized polydopamine and their application was explored in the removal of water pollutants and the delivery of anticancer drugs.The main work is as following:1.The degradation of pollutions in water with the preparation of functional polydopamine microtubular motorsAs a kind of most common azo dye,methylene blue（MB）is one of the main sources of organic pollutants in water.It has been found that MB would cause serious health problems after entering the human body.The lead ion(Pb²⁺)and cadmium ion(Cd²⁺)are two typical heavy metal ions in industrial wastewater that cannot be biodegraded,accumulate in the biosphere and enter organisms along the food chain.Therefore,it is of great significance to improve the degradation of MB and the removal efficiency of heavy metal ions in water environment.In this thesis,we prepared polydopamine（PDA/Pt）microtubular motors by template electrodeposition.The Fe₃O₄-PDA/Pt microtubular motors were obtained by modifying the surface of microtubular motors with Fe₃O₄ nanoparticles.HO·radicals are produced by the Fenton-like reaction of Fe²⁺and H₂O₂ on the interface of Fe₃O₄-PDA/Pt microtubular motors.Then,MB react with HO·and are degraded into CO₂ and H₂O rapidly.The experimental results show that Fe₃O₄-PDA/Pt microtubular motors can degrade MB in different pH environments.At pH=8,Fe₃O₄-PDA/Pt microtubular motors can achieve rapid（16 min）,efficient（≥90%）degradation of MB.At the same time,microtubule motors can be reused.The degradation ratio is still about 71%after three times usage.In addition,because there are abundant phenolic hydroxyl and amine functional groups of PDA on the surface of the PDA/Pt microtubular motors,a variety of metal ions can be chelated with PDA.With its excellent adsorption capacity for metal ions,the microtubule motor offer an rapid removal of Pb²⁺and Cd²⁺（85%and 89%）in a short time（6 min）.Therefore,the functionalized polydopamine microtubular motors hold promise for wastewater treatment applications.2.The fabrication of functionalized polydopamine Janus microsphere motor for drug deliveryThe Janus microsphere motor with asymmetric structure is one of the most common artificial structures of micro/nano motors.Magnesium（Mg）-based Janus microsphere motor can generate H₂ bubbles to propel microsphere motor in multiple solution environment（e.g.,water,acid,salt and blood）.The product,Mg²⁺,has no toxic and side effects on the human body.Thereby,the Mg Janus microsphere motor can be applied in drug delivery.In this thesis,polydopamine（PDA/Eudragit/Mg）Janus microsphere motors were prepared with polydopamine nanoparticles（PDA NPs）as the outermost layer,Eudragit as the middle layer and metal Mg spheres as the substrate.The two drug-loaded microsphere motors are fabricated by the combination of PDA NPs and anticancer drugs doxorubicin（DOX）and bortezomib（BTZ）throughπ-πinteraction and phenolic hydroxyl groups bonding with boric acid to form borate bonds,respectively.Drug loading efficiency of PDA NPs to DOX and BTZ were determined.At the same time,the drug-loaded motors can released the two kind of drugs in a weak acidic（pH=5.0）environment which are better than in a neutral（pH=7.4）environment.Drug release experiments show that PDA has pH-sensitive drug release performance and holds promises for drug release in a slightly acidic environment of the carcinoma.Therefore,the functionalized polydopamine Janus microsphere motors have great application potential in drug delivery application.