Research On The Method Of Controlled Release Of Micro-nano Drugs By Focused Ultrasound

Drug targeted therapy for malignant tumor is one of the hot technologies in current research,aiming to improve the local drug concentration in the focus area and reduce the damage of drug toxicity to healthy tissues.Drug delivery in human body depends on blood circulation and is in a relatively passive state.Enhancing the active control of drug delivery is one of the difficulties.Therefore,in this paper,two drug types,nanoparticles and microbubbles,are taken as controlled objects,and a targeted drug release technology of ultrasound in vitro is proposed.The specific research contents are as follows:Firstly,taking nanoparticles as the research object,through the COMSOL finite element calculation and experiment,it is found that the acoustic energy can generate a synthesis effect of the potential energy well and the acoustic streaming through in the blood vessel phantom made of agarose hydrogel.When the acoustic intensity is within the range of 7.5 W/cm² and 20.8 W/cm²,the 2.5 MHz focused ultrasound beam can effectively aggregate the nano-Si O₂ particles and manipulate the cluster’s movement,and the maximum aggregation diameter within 35 s can reach 418μm.Then,taking microbubbles as the research object,the finite element model of the effect of acousticfield on microbubbles is established,the principle of the interaction of acoustic radiation force and flow resistance is revealed,and the trajectory of microbubbles is predicted by the particle tracking model.The experiment combines ultrasonic capture and ultrafast plane wave imaging technology together,which is a combination of control and monitoring,to realize the movement control and real-time monitoring of microbubble at the depth of 10 mm under the flow rate of 0.03 ml/min.Finally,a scheme of ultrasound microbubble driving assisted by medium boundary is proposed.Anon-contact acoustic microbubble driving based on the difference of boundary acoustic properties is formed by the combination of ultrasound and bubble wall,so as to realize the fine adjustment of microbubble’s local position in the blood vessel.Through simulation and experiment,it is found that the microbubbles can gather rapidly to the wall within 2 s,and then complete the movement of rotation with an average angular velocity of 2.84°/s.