肿瘤归巢穿膜肽介导的靶向相变脂质纳米粒的制备及特性研究

Preparation and characteristics of targeted phase-shift lipid nanoparticles mediated by tumor homing and penetrating peptide

目的制备一种新型超声造影剂一肿瘤归巢穿膜肽tLyP-1介导的靶向相变脂质纳米粒，并评价其特性。方法薄膜水化-声振法制备纳米粒，检测其形态、分布、粒径及表面电位；加热和低强度聚焦超声仪（lowintensityfocusedultrasound，LIFU）辐照观察其液气相变及体外增强超声显影情况；激光共聚焦显微镜定性观察、流式细胞仪定量分析其体外靶向性和细胞穿膜性；CCK8检测其细胞毒性。结果tLyP-1介导的靶向相变脂质纳米粒大小均一、分散性好，粒径为（399．50±29．98）nm，表面电位为（3．28±1．72）mV；加热到45℃可致相变，一定功率的LIFU辐照后也可致相变并能增强超声显像（P〈0．05）；激光共聚焦显微镜结果显示tLyP-1介导的靶向相变脂质纳米粒可靶向聚集到MDA-MB-231细胞膜周围且部分穿膜进入到细胞质中，而HUVEC细胞膜表面未见明显聚集和穿膜现象，无tLyP-1介导的相变脂质纳米粒在两种细胞周围也未见明显聚集和穿膜现象；流式细胞仪结果显示MDA-MB-231细胞内tLyP-1介导的靶向相变脂质纳米粒的荧光强度明显高于其余各对照组（P〈0．05）；CCK8检测显示tLyP-1介导的靶向相变脂质纳米粒对两种细胞活性无明显影响（P〉0．05）。结论成功制备了肿瘤归巢穿膜肽tLyP-1介导的靶向相变脂质纳米粒，其能有效地靶向乳腺癌MDA—MB-231细胞并穿膜进入细胞质中，且一定功率的LIFU辐照后能增强超声显影，有望成为一种新型肿瘤靶向的超声造影剂和实现肿瘤细胞水平的超声分子成像。

Objective To prepare a novel ultrasound contrast agent, targeted phase-shift lipid nanoparticles mediated by tumor homing and penetrating peptide tLyP-1, and to evaluate its characteristics. Methods The nanoparticles were prepared by filming-rehydration and acoustic-vibration methods. The morphology, distribution, particle size and zeta potential were detected. After heating and irradiating of low intensity focused ultrasound （LIFU）, the phase-shift characteristic and the enhancement effect in vitro were observed. The tumor homing and cell-penetrating properties of the nanoparticles were examined by eonfocal laser scanning microscopy and flow cytometry. The eytotoxicity of the nanopartieles was evaluated by CCK8 assay. Results The size and distribution of nanoparticles were uniformed. The size and zeta potential of nanoparticles were （399.50 ± 29.98）nm and （3.28 ±1.72）mV, respectively. When the nanoparticles were heated to a temperature of 45 ℃ or after irradiated by LIFU, nanoparticles generated phase-shift and enhanced ultrasound imaging in vitro （ P 〈 0.05）. The confocal laser scanning microscopy showed that nanoparticles mediated by tLyP-1 can targetedly aggregate to cell membrane of MDA-MB-231 and penetrate into the cell, but not to HUVEC. The flow eytometry showed that intracellular fluorescence intensity of nanopartieles mediated by tLyP-1 in MDA-MB-231 group was higher than that in control groups （ P〈0.05）. The CCK8 assay indicated that different concentrations of nanoparticles had no significant effects on cell activity （P 〉 0.05 ）. Conclusions A novel ultrasound contrast agent, targeted phase-shift lipid nanoparticles mediated by tumor homing and penetrating peptide tLyP-1, is prepared successfully. It can target to MDA-MB-231 cell and penetrate into the cell in vitro, and enhance ultrasound imaging in vitro after LIFU irradiation, which expected to become a novel tumor targeted ultrasound contrast agent and achieve ultrasound molecular imaging at the level of tumor cell.