Experimental study on preparation and targeting in vitro of nanobubbles with two-fold amount of folate

Objective To investigate the selective targeting ability of a novel folate-modified nanobubbles with two-fold amount of folate [(FOL)2-NBs]. Methods DSPE-PEG2000-AD-(FOL)2 with two-fold of folate per DSPE-PEG2000 chain was synthesized and then tested by 1H nuclear magnetic resonance (1H NMR). The novel (FOL)2-NBs was prepared using the mechanical shaking method based on lipid-stabilized perfluoropropane. The bubble size was measured by Malvern laser particle size analyzer and the contrast enhancement ability was also detected with imaging machine using a self-made agarose mold. The experiment of selective targeting ability was also carried out in human breast cancer MCF-7 cell with over-expression of folate receptor (FR) using fluorescence activated cell sorting (FACS). Results The result of 1H NMR proved that DSPE-PEG2000-AD-(FOL)2 was successfully synthesized, and the purity reached up to 90%. The novel prepared (FOL)2-NBs showed superior contrast enhancement ability with a particle size of (286.87±22.96)nm. Compared with the conventional NBs, the novel (FOL)2-NBs exhibited improved selective cellular targeting ability proven by FACS. Conclusions A novel nanobubble with improved selective targeting ability is successfully prepared and shows great potential in extravascular imaging and curation in FR overexpressed tumors. Key words: Contrast-enhanced ultrasound; Nanobubble; Folate receptor; Breast cancer