Application Study Of Stimulus-Response Biomimetic Microspheres In Environmental And Biomedical Fields

In recent years,with the rise of nanotechnology,micro-nano materials have developed rapidly.Among them,micro-nano motors have received more and more attention from researchers due to their unique self-driving characteristics.The micro-nano motor is a kind of micro-nano material that can convert the energy of the surrounding environment,such as chemical energy,light energy,and heat energy,into its own mechanical energy.There are many types of them.According to their different geometric shapes,they can be divided into: shelllike micro-nano motors,cylindrical micro-nano motors,tubular micro-nano motors,spherical micro-nano motors,conical micro-nano motors,etc.;according to the different sources of energy supply,they can be divided into chemically driven micro-nano motors and physically driven micro-nano motors.Specifically,it can be divided into: bubble driven micro-nano motor,self-diffusion micro-nano motor,magnetic field driven micro-nano motor,light field driven micro-nano motor,thermal field driven micro-nano motor,etc.Nowadays,the technological revolution triggered by nanoscience has opened up new prospects for dealing with special environmental problems.Among them,micro-nano motors have shown great application prospects in environmental restoration.The size of the micronano motor is small,and it can reach positions that cannot be reached by traditional means to achieve in-situ decontamination.Moreover,its self-driving characteristics can cause selfstirring,improve the mass transfer process,speed up the mixing speed,and improve the efficiency of detection and removal.Moreover,due to its strong biocompatibility and size close to biological cells,micro-nano motors also have broad application prospects in the medical field,including precise imaging,cell identification and capture,targeted drug delivery,phototherapy in cancer,micro-nano surgery and other aspects.In this thesis,we tried to prepare three kinds of stimulus-response bionic microsphere motors through external functionalization based on natural and artificial microspheres:multifunctional chlorella microspheres,sporopollenin-exine-capsule micromotors and mesoporous silica micromotors,which are used to detect adsorbed pollutants;degrade dye wastewater and improve cancer imaging.First,through a variety of modification strategies based on biomimetic dopamine,the natural biological material chlorella microspheres can be given magnetic properties,and the magnetic properties can be precisely controlled,and used for the enhanced adsorption of heavy metals,the fluorescence detection of metal ions,and the in-situ adsorption of oil stains and transportation.Secondly,using the sporopollenin-exinecapsule(SEC)of natural pollen as the substrate,the hollow structure is used to load horseradish peroxidase(HRP),and the near infrared(NIR)responsive polymer is modified on the outer layer by self-assembly method.The outer layer of dopamine constitutes a micromotor of the sporopollenin-exine-capsule with two drive systems of "magnetic propulsion" and "chemical propulsion".The motor can be propelled to the polluted place under the control of a magnetic field,and under near-infrared stimulation,it releases a pollen capsule that can be driven by a chemical reaction and the peroxidase loaded inside,and the capsule realizes the rapid degradation of organic pollutants at a fixed time and at a fixed point.Finally,the mesoporous silica microspheres were prepared by the microemulsion method,and the near-infrared response driving and magnetic resonance(MR)imaging were realized by asymmetrically modifying the gold layer and loading gadolinium ions.The microsphere can be used as an active imaging agent.In vivo experiments in mice have proved that it can achieve effective penetration in tumor sites under the action of near-infrared,and enhance the effect of in vivo magnetic resonance imaging.