Folate receptor ( FR )-targeted fluorescent nanoprobes ( RSiNPs-Folate ) were constructed by modifying Rubpy-doped silica nanoparticles ( RSiNPs) with folic acid ( FA) based on click chemistry coupling method, which was successfully used for cancer cell imaging. Firstly, RSiNPs were prepared by St?ber method and modified with azide groups through the hydrolysis of silane coupling agents ( Az-PTES ) , then propargyl folate were conjugated onto the nanoparticle surfaces via click reaction. It was demonstrated that the FA-functionalized nanoprobes were successfully prepared by monitoring the characteristic peak of the azide group at 2105 cm-1 before and after coupling. In the condition of physiological pH, the nanoprobes exhibited strong red emission at 601 nm when excited at the 458 nm excitation wavelength. The cell imaging results showed that RSiNPs-Folate could effectively target FR-positive HeLa cells, while no obvious fluorescence was observed for FR-negative A549 cells. The receptor-mediated imaging mechanism was confirmed by free FA competition experiments. More importantly, HeLa cells could be selectively recognized and imaged in the mixing cell system. Compared with the carbodiimide conjugation protocols, the click-functionalized nanoprobes had many advantages such as simple synthesis procedures, mild reaction conditions and high yields, which could be potentially used for fluorescent labeling and imaging of different cancer cells.%采用点击化学偶联法对荧光二氧化硅纳米粒子表面进行叶酸功能化修饰,构建了一种叶酸受体靶向的荧光纳米探针,并成功用于肿瘤细胞的成像研究.首先通过St?ber法制备包裹钌联吡啶的荧光二氧化硅纳米粒子(RSiNPs),然后利用叠氮化硅烷偶联剂(Az-PTES)的水解反应在其表面引入叠氮基团,最后通过点击化学反应将炔丙基叶酸衍生物偶联到粒子表面.利用红外光谱对其偶联前后的叠氮基特征峰(2105 cm-1)进行表征,证实了叶酸功能化的荧光纳米探针(RSiNPs-Folate)已被成功制备.在生理pH条件下,以458 nm为激发波长,RSiNPs-Folate在601 nm处发射较强的红色荧光,且光稳定性较好.细胞成像结果表明,这种叶酸受体靶向的荧光纳米探针能够有效地标记叶酸受体呈阳性的人宫颈癌细胞(HeLa),而叶酸受体呈阴性的人肺癌细胞(A549)未观察到明显的荧光.叶酸竞争性结合实验证明了这种叶酸受体介导的肿瘤细胞成像机制.此探针能够实现混合细胞体系中HeLa细胞的选择性识别与荧光成像.与酰胺化反应偶联叶酸相比,这种点击功能化的纳米探针的合成方法简单、反应条件温和、产率高,可用于不同肿瘤细胞的荧光标记与成像.
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