[Preparation and evaluation of microbubble ultrasound contrast agent with N-carboxymethyl chitosan].

OBJECTIVE To prepare microbubble, made of N-carboxymethyl chitosan, as ultrasound contrast agent and evaluate its characteristics and acoustic effects in vivo. METHODS Oil-Water-Oil multiple emulsion/solvent evaporation method was used to prepare the microbubble contrast agent. Both optical micrography and scanning electron micrography were performed to determine the bubble size and morphology. The acoustic effect of the N-carboxymethyl chitosan echo contrast agent was evaluated in vivo in rabbit. Liver echo images were recorded with ultrasound machine before and after intravenous bolus injecting 0.5 ml of the agent. RESULTS The novel N-carboxymethyl chitosan echo contrast agent was formulated as lyophilized product, with a mean diameter of 2-3 microm and a shell thickness of 250-300 nm. Its size is relatively uniform. The imaging effect was remarkably enhanced with the ultrasonic contrast agent when applied in rabbit livers. CONCLUSION It is feasible to prepare excellent microbubble ultrasound contrast agent with N-carboxymethyl chitosan as membrane components.