Preparation Of Magnetically Driven Pollen And Ultrasonic Driven Carbon Quantum Dot Modified Micronmachines

The swimming micro/nano machine is a micro/nano scale device which can convert chemical energy or other forms of energy into autonomous motion.Micro/nano machines have received a great deal of attention in the past few decades,and their scale makes them potentially navigable to difficult-to-reach biological tissues for many biomedical applications.Among many swimming micro/nano machines,micro/nano machines controlled by external physical fields such as magnetic field and ultrasonic field have been widely concerned in the field of biomedicine because they are free from toxic chemical fuel.The construction of micro/nano machines based on outfield control is expected to further expand the potential application fields of micro/nano machines and develop new self-driven micro/nano machines.In this thesis,sunflower pollen and polycarbonate membrane were used as templates to prepare two kinds of moving micron machines.One is a pollen template micro/nano machine that can carry out countercurrent movement under the control of external magnetic field.The other is an external ultrasonic controlled polymer multi-layer micro/nano machine that modifies carbon quantum dots based on controllable assembly technology.In this thesis,the shape magnetic structure of pollen is constructed based on pollen.The magnetic structure of pollen as a swimming micronmachine under alternating magnetic field was studied.The magnetic field frequency and magnetic field strength are analyzed for the motion of the magnetic traveling micron machine.The effect of speed is to use a 300 ?m quartz square microfluidic channel as a blood vessel model to study the reverse blood flow motion of the magnetic swimming micrometer machine in the blood vessel.The experimental results show that the maximum countercurrent flow rate of the magnetic swimming micrometer machine can perform countercurrent movement is 7.50 mm/s.In order to develop swimming micro/nano machines suitable for biomedicine,this thesis constructed a carbon quantum dot-modified external ultrasound-controlled tubular micro/nano machine,using hydrothermal method to prepare zero-dimensional carbon quantum dots,and the ultraviolet spectrum and fluorescence spectrum were characterized,and the fluorescence quantum yield was 18% by reference method.Then,using the polycarbonate film as a template,a tubular micro/nano machine was prepared by layer-by-layer self-assembly method.In this thesis,the carbon quantum dots are combined with the tubular swimming micro/nano machine,and the carbon quantum dots are modified under the control of an external ultrasonic field.The tubular micro/nano machine successfully carried out a controlled movement.The research shows that as the ultrasonic amplitude increases,the movement speed of the tubular micro/nano machine modified by carbon quantum dots increases.When the ultrasonic amplitude is fixed at 10 Vp-p,the ultrasonic frequency is 390.The movement speed of the carbon quantum dot modified tubular micro/nano machine at 390 k Hz is 101.11 ?m/s,which is much higher than the movement speed of the carbon quantum dot modified tubular micro/nano machine at other frequencies.In summary,this thesis has realized the construction of magnetic pollen swimming micrometer machines and ultrasonically driven carbon quantum dots modified tubular micrometer machines.It not only lays a foundation for the countercurrent movement of micronmachines,but also provides a new design idea for the development of micronmachines.