中文摘要：

目的探讨以与血管内皮生长因子（VEGF）的主要受体KDR特异性结合的短肽K237（P）为配体制备靶向脂质体超声造影剂（P-Bio-Av-Bio-Mbs）的方法。方法 采用生物素-亲和素桥接法构建P-Bio-Av-Bio-Mbs,流式细胞术筛选最佳配体适配剂量,光镜及荧光显微镜观察靶向微泡与KDR强阳性表达的人大肠癌LOVO细胞结合情况,计算花环形成率。分别以5、50、99ml/h速率水流冲刷,光镜观察靶向微泡与LOVO细胞结合情况。结果 不同亲和素剂量下（0、2、6、10、30μg）,微泡表面亲和素携带率差异有统计学意义（P〈0.05）。Mavidin=6μg时,携带率增长达平台期;不同短肽剂量下（0、30、40、50、60、70、100μg）,微泡表面短肽携带率差异有统计学意义（P〈0.05）,当MK237=50μg时,微泡表面短肽携带率增长达平台期。光镜下KDR强阳性表达的LOVO细胞周围花环形成率高达90.52%,荧光显微镜下微泡外壳发出明亮绿色荧光。随冲刷速度增加,靶细胞周围黏附的靶向微泡减少,在99ml/h冲刷速度下,靶细胞周围仍可见花环结构。结论 通过生物素-亲和素桥连作用,短肽K237被有效装配在P-Bio-Av-Bio-Mbs表面,体外具有靶向特异性及一定稳定性。流式细胞术是筛选靶向微泡配体适配剂量的可靠方法。

英文摘要：

Objective To assess preparation method of a new kind of targeted liposome ultrasonic contrast agent with small peptide K237 as the ligand which can combine specifically with KDR as the main receptor of VEGF.Methods Targeted bubbles（P-Bio-Av-Bio-Mbs） were formed through ＂biotin-avidin＂ bridge grafting.Flow cytometry screening was performed to explore the best dose of the ligands,then targeted-bubbles were incubated respectively with LOVO and LS174T which were KDR expressed in different cells.Meanwhile,rosette formation rate was calculated.Results The bubble surface＇s avidin-carrying rates were significant different（P0.05） on different dosages of avidin（0,2,6,10,30 μg）.When M_avidin=6 μg,the avidin labelling ratio reached plateau.There were significant differences in the ratio of peptide K237 labelling（P0.05） as different peptide dosages（0,30,40,50,60,70,100 μg）.When M_k237=50 μg,the peptide labelling ratio reached plateau.In KDR sharply positive expressed LOVO cells,the surrounding rosette formation rate was as high as 90.52% with strong fluorescence intensity.Targeted microbubbles decreased as the water velocity increased.When the velocity reached 99 ml/h,rosette formation still could be seen surrounding the targeted cells.Conclusion KDR-targeted liposome contrast agent with small peptide liganded has been successfully prepared through biotin-avidin mediation,and showed special targeting ability and stability in vitro.Flow cytometry can quantitatively analyze the best dose of ligands carrying targeted microbubbles.