The Preparation Of Nanoparticles And Their Influence On Cavitation Threshold Of Exploration

In recent years, with the application of ultrasonic in medicine greatly improved the progress of ultrasonic medical diagnosis and treatment. Ultrasonic medical begin to enter a new stage in the diagnosis and treatment of the human microcirculation system. Ultrasound used on drug particles target specific areas for drug release and action, realizing ultrasonic non-destructive testing. The focus of the research is the use of cavitation effection, achieved control drug particles therapeutic precisely. Sonoporation is a term used to describe a phenomenon that the ultrasound could temporarily change the structure of cell membrane, form a reversible hole in the cell membrane, promoting low molecular weight or high molecular weight particles into the cells. The size of the holes in the cell membrane perforated by acoustic very suitable for large molecules transmission such as DNA and drugs, so the ultrasound widely applied for promoting gene or drugs into the targeted living cells. In the study of this process, transient cavitation is considered plays an important role in the process of sonoporation. Sonoporation derived from two main aspects:one is the damage of the shock wave and jet force of microbubble vibration crushing near cell membrane on the cell, the other is the microbubble wall movement caused the change of the structure of the cell membrane. Although in recent years the results are generally considered both cavitation and microbubbles are enhancing cavitation effect on cell to improve the genes or the drugs transmission efficiency, but the mechanism of sonoporation is not studied clearly.This paper aims to build an ultrasonic system, based on spectrum analysis method for cavitation field research, hydrophone as measuring device, using spectrum analyzer measurements to analyse different concentration and size of the magnetite particles solution,silica particles solution, and distilled water cavitation noise. The main works are conducted in my thesis are outlined below.(1) First illuminate the nanometer biological materials are used in modern medical diagnosis and treatment. Through the introduction of ultrasonic into organism non-destructive mechanism, provides the basis of theory for ultrasonic biomedical. Ultrasound molecular imaging is a new emerging discipline in recent years, imaging contrast source is specific molecular in vivo, using the level characteristics of molecular located in lesions of internal tissue, at the molecular level real-time and non-destructive measuring pathological processes in vivo for early diagnosis and detection of complex diseases. The development of ultrasound contrast agents and imaging method improve the ultrasound diagnosis of disease and the identification efficiency.(2) Synthesizing superparamagnetic iron oxide nanoparticles/colloids for labeling of cell. On the basis of searching the reaction conditions and for specific size of particles, using ultrasound assisted chemical coprecipitation method, sol-gel method, respectively, synthesis of magnetic nanoparticles and silica nanoparticles. The main characters of the particles were investigated by transmission electron microscopy, scanning electron microscopy, X-ray diffraction, magnetic properties studied by vibrating sample magnetometer. The synthesized black power show face-centered of anti-spinel crystal phase. The average diameter of magnetic particle is about10nm, magnetic saturation intensity is64.396emu/g, and available as MRI contrast agent on physical properties.(3) Design a ultrasound system for cavitation noise detection. Through the integration, we have established a set of ultrasonic cavitation noise measuring apparatus composed of the ultrasonic generator, ultrasonic power meter, sensor, spectrum analyzer. Separated cavitation noise spectrum by the spectrum statistical method. From nose intensity in three different liquids shows that with increasing of the concentration, cavitation nuclear increased, enhanced cavitation effect, reduced tthe cavitation threshold, the same with the nano-particles gradually increasing.