ABSTRACT
<p><b>OBJECTIVE</b>To prepare an ultrasound microbubble contrast agent using PLLA-PEG-PLLA copolymer as the shell material, and test their acoustic characteristics in vitro.</p><p><b>METHODS</b>PLLA-PEG-PLLA tri-block co-polymers were synthesized by ring-opening polymerization. Microbubbles were prepared by using double emulsion technique. Light microscope and scanning electron microscope were applied to observe the morphology of the microbubbles. Their size distribution was analyzed using MASTERSIZER 2000. The acoustic characteristics of microbubbles were tested by using color Doppler Ultrasonography.</p><p><b>RESULTS</b>Microbubbles were well dispersed in water. Contrast enhancement was stronger and longer lasting at low mechanical index.</p><p><b>CONCLUSION</b>The polymer-encapsulated microbubbles prepared by using double emulsion technique with PLLA-PEG-PLLA as the shell material can be used as an ultrasound contrast agent.</p>