Preparation And Characterization Of Air-Filled Albumin Microspheres As Ultrasound Contrast Agent

Ultrasound contrast agent has been paid close attention since a few years,it can enhance much more colorful Doppler signals remarkablely and normal viscera substance and the gray scale picture of tumor strengthen,and improve diagnostic accuracy and application range.At the present time various contrast agents have been on the market abroad,Beisheng pharmaceutical factory is producing sonic albumin microspheres(MS) contrast agent- Shengweixian injection.Contrast agents that have already appeared on the market are divided into two kinds:air-filled(the first generation ultrasound contrast agents) and inert gases- filled contrast agents(the second generation ultrasound contrast agents),two types contrast agents all can strengthen definition,but the first generation ultrasound contrast agents stay time in the body short,their package,albumin film of protection air or surface active agent break quickly in the blood,the air protected overflow,so the function of improving imaging can maintain only for 1～3 minutes.In the meantime,because of the restriction of manufacturing method,the diameter scope of MS is wide(1～12 microns)and influence imaging effect.The second generation ultrasound contrast agents overcome time problem,but they are mainly ejected the outside of the body by lung,their tiny bubbles can fuse large bubbles and produce tiny aeremia.So the research on contrast medium that long lasting time and small scope and small danger and obvious clarity is still very important content in diagnose.The preparation process of MS was optimized by using ultrasonic atomizing method and taking particle diameter of MS as the observing index in this experiment,albumin is membrane wall,air is gas-filled.The optimized process parameters were:albumin density was 5%,solvent was ethanol without water,ultrasonic atomizer power was 225W,thermostat temperature was 95℃,glutaraldehyde density was 0.1%as cross-linking agent,solidified time was 90 min,stirring velocity was 2000 r/min, vacuum pump power was 280W,volume of cross-linking agent was 1.35～1.5 ml in 100 ml MS solution.MS prepared in this preparation process was symmetrical and round,the average diameter was ranged from 2 to 5μm,diameter distributing was narrow,the dispersing was good,the use was much more safe,this process can produce continuously and batchly and keep consistency,on the one hand it could meet demand for industrialization,on the other hand it could guarantee stability of the products,it can be a reference for the preparation process of gas-filled albumin microsphere as ultrasound contrast agents.