基于脂质体的新型肿瘤成像荧光探针的构建及初步评价

Preparation and evaluation of a novel liposome-based fluorescent probe for tumor imaging

本研究以脂质体作为药物载体,利用磷脂酰乙醇胺(phosphatidyl ethanolamine,PE)和吲哚花青绿(indocyanine green,ICG)的疏水相互作用,制备了纳米荧光探针Lipo ICG。再通过人血清白蛋白(human serum albumin,HSA)包裹,对脂质体的结构进行固化,制备了一种新型的纳米荧光探针H-LipoICG。实验制得的Lipo ICG为大小均匀的圆球形,粒径约为94.47 nm,zeta电位约-43.5 m V,包封率(encapsulation efficiency,EE)约81.5%;H-LipoICG为大小均匀的圆球形,粒径约为121.5 nm,zeta电位约为-32.3 m V,EE约为98.2%。说明通过HSA包裹,能提高脂质体的载药量。药物释放结果表明,ICG在Lipo ICG中的释放速度比在H-LipoICG中快,证明HSA的包裹能使脂质体的结构更稳定,有利于维持ICG的荧光强度。通过Cell Counting Kit-8(CCK-8)实验研究材料对人乳腺癌细胞MCF-7的毒性,证明Lipo ICG和H-LipoICG材料对细胞无毒,具有良好的生物相容性。通过研究材料在荷瘤小鼠体内的组织分布,说明HSA修饰后的脂质体H-LipoICG比Lipo ICG具有更强的肿瘤靶向性和更高的荧光强度,能够在注射8 h后富集于肿瘤组织,显著勾勒出实体瘤的轮廓并维持荧光信号至24 h。H-LipoICG具备良好的肿瘤荧光成像性质。

In this study,a fluorescent nanoprobe based on liposome was synthesized by the hydrophobic interaction of phosphatidyl ethanolamine and indocyanine green（ICG）.The nanoprobe was called LipoICG.In order to enhance the stability of liposome,we made a new LipoICG by coating it with human serum albumin（HSA）.The new fluorescent nanoprobe,H-LipoICG,was produced for tumor imaging.The LipoICG and H-LipoICG were observed as spherical shape with uniform size distribution.The particle size of LipoICG was 94.47 nm,zeta potential was-43.5 mV and encapsulation efficiency（EE） was 81.5%.The particle size of H-LipoICG was 121.5 nm,zeta potential was-32.3 mV and EE was 98.2%.The coating of HSA could enhance the stability of liposome and increase the EE of ICG.Studies on drug release demonstrated that the release of ICG in H-LipoICG was slower than LipoICG,which suggests that HSA may reduce the ICG leakage from liposome,the fluorescence intensity could be enhanced in the nanoprobe.The Cell Counting Kit-8 assay demonstrated that LipoICG and H-LipoICG was not toxic for MCF-7 cells with good biocompatibility.In the study of biodistribution in mice,our experiments demonstrated that H-LipoICG had better tumor targeting ability and exhibited an enhanced fluorescence intensity than LipoICG.An optimize tumor contrast was observed after 8 h intravenous administration,the tumor margins could be clearly detected for up to 24 h after injection.So,H-LipoICG was an effective fluorescent probe for tumor imaging.