摘要/Abstract

构建了一种近红外二区成像探针，能对脑部病变进行近红外二区荧光成像.利用脑靶向肽Angiopep-2对Ag₂S量子点进行修饰，Ag₂S量子点和Angiopep-2多肽经EDC和NHS介导，通过氨基和羧基的缩合反应进行连接，采用琼脂糖电泳、动态光散射及透射电镜等方法对材料进行表征，并观察了材料对脑胶质瘤细胞U87MG的细胞毒性、材料在该细胞中的分布、摄取以及在实体瘤荷瘤鼠中的分布情况.结果显示，Ag₂S量子点水合粒径约为6 nm，经肽修饰后粒径约为8 nm，表面zeta电位正电性增强，在琼脂糖电泳中，肽修饰后Ag₂S迁移距离较Ag₂S短，表明Angiopep-2多肽修饰到了量子点上.经过细胞实验发现，修饰后的Ag₂S量子点在100 μg/mL以下没有细胞毒性，脑胶质瘤U87MG细胞对Angiopep-2多肽修饰的Ag₂S较Ag₂S具有更高的摄取.经过初步的实体瘤动物实验发现，Angiopep-2修饰的Ag₂S能在皮下瘤模型中出现分布和聚集，说明修饰后的Ag₂S量子点具有一定脑胶质瘤细胞的靶向性.
关键词: 硫化银量子点, 脑靶向, Angiopep-2, 近红外二区成像
Ag₂S quantum dot with excellent NIR-Ⅱ fluorescence can provide deeper tissue penetration (>1.1 cm) and higher spatiotemporal resolution (25 μm, 50 ms) in comparison to the conventional fluorophore. In this study, we designed a NIR-Ⅱ probe based Ag₂S quantum dot for imaging of brain tumor. Angiopep-2 was used to modify Ag₂S quantum dot, which is a 19-mer peptide exhibiting high binding efficiency with low-density lipoprotein receptor-related protein-1 (LRP-1) of blood brain barrier and glioma. Due to the surface of Ag₂S quantum dots with carboxyl groups and angiopep-2 peptide with amino groups, Ag₂S was conjugated with Angiopep-2 (Ag₂S-ANG) through the condensation reaction of amino and carboxyl groups mediated by EDC and NHS. The structure, size and spectral properties of Ag₂S-ANG were characterized by agarose electrophoresis, dynamic light scattering transmission, electron microscope (TEM), UV-vis spectrometer and NIR fluorescence spectrometer, respectively. Results showed that Ag₂S-ANG had a short migration distance compared with Ag₂S in the agarose gel electrophoresis. The hydrate particle size of Ag₂S was approximately 6 nm, Ag₂S-ANG was approximately 8 nm and its zeta potential exhibited electropositive reinforcement, zeta potential of Ag₂S is -11.47±1.56 mV and Ag₂S-ANG is +28.7±1.35 mV. Ag₂S-ANG exhibited similar absorbance and fluorescence spectra to Ag₂S, except a slight enhancement of emission peak. These results indicated that Ag₂S-ANG was synthesized successfully. We further observed its cell cytotoxicity, distribution and uptake in Uppsala 87 Malignant Glioma cells(U87MG), and in vivo distribution in the solid tumor-bearing mouse. Ag₂S-ANG had no obvious cytotoxicity when the concentration is inferior to 100 μg/mL and had more uptake in U87MG cells than that of Ag₂S. In animal experiments, glioma tumor-bearing mice were used to investigate the distribution and tumor targeting of Ag₂S-ANG. Results showed that Ag₂S-ANG can distribute and accumulate in subcutaneous tumor site, indicating that Ag₂S-ANG had the potential of targeting the glioma cells.
Key words: Ag₂S quantum dot, brain-targeting, angiopep-2, NIR-II imaging References


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