Objective       To prepare targeted nanoscale microbubbles (NBs) with G250 monoclonal antibodies targeting renal cell carcinoma (RCC)

and explore its targeting ability to RCC in vitro and in vivo.        Methods       Mechanical oscillation method was used for preparing blank NBs and its stability was observed. Targeted NBs was prepared by biotin-avidin linking technology and verified by immunofluorescence assay. The expression of G250 in 2 kinds of RCC cells (786-O and ACHN) was identified by immunofluorescence assay. Targeting ability of the 2 kinds of NBs in vitro was identified by target binding assay. In the nude mice model of RCC

contrast-enhanced ultrasound imaging was used for imaging the 2 kinds of NBs

and the dynamic images were collected and analyzed in the quantitative analysis software Qlab 8.1.        Results       The blank NBs and targeted NBs in average particle sizes of 404.9 nm and 611.4 nm

respectively

were successfully prepared

and with good stability. The targeted NBs were labeled with FITC

thus showing green fluorescence. Immunofluorescence assay confirmed that membrane antigen G250 was expressed in 786-O cells

but not expressed in ACHN cells. In the cell binding experiment

it was found that the targeted NBs were able to specifically bind to 786-O cells

but unable to bind to ACHN cells. In vivo ultrasound contrast imaging showed that the mean value and maximum value of the blank NBs and targeted NBs in 786-O cells were significantly different from those in ACHN cells in the nude mice model (average mean: 11.74±0.52 vs 16.34±0.40

P=0.001; maximum value: 13.07±0.94 vs 18.09±0.82

P=0.003).        Conclusion       The prepared targeted NBs targeting G250 can specially bind to 786-O cells in vitro

and significantly enhance the ultrasound imaging effect in vivo.