叶酸偶联金纳米棒靶向探针制备及体外肝癌细胞对其摄取状况的研究

Preparation of nanorods probes targeting cancer cells and uptake of HepG2 cells in vitro

目的探讨叶酸偶联的二氧化硅包覆的金纳米棒（GNRs@SiO2-FA）探针制备方法和其光学性质，检测探针靶向性，并观察其进入细胞过程。方法采用种子生长法制备出金纳米棒，以SiO2作为壳材，制备出GNRs@SiO2，最后偶联叶酸得到GNRs@SiO2-FA。（1）利用透射电镜、紫外光谱对制备出的GNRs@SiO2-FA探针进行检测。（2）取对数生长期肝癌HepG2细胞随机分为2组，分别加入金元素浓度为40．0×10^-6、20．0×10^-6、10．0×10^-6、5．0×10^-6、2．5×10^-6的GNRs@SiO2-FA和GNRs溶液，采用四甲基偶氮唑盐（MTT）微量酶反应比色法测得吸光度值（A值），以此判断其细胞毒性。（3）将细胞随机分为2组，分别加入相同金元素浓度的GNRs@SiO2-FA和GNRs@SiO2溶液，然后孵育2、4、8、16、24h时，应用电感耦合等离子体质谱法（ICP—MS）监测GNRs@SiO2-FA细胞摄入的靶向性。（4）用透射电镜观察GNRs@SiO2-FA进入细胞过程。所得数据用元±s表示，单因素方差分析进行两两组间比较，P〈0．05为差异有统计学意义。结果紫外图谱证实成功制备GNRs@SiO2-FA。对2组金浓度相同细胞的A值进行方差分析比较，差异均有统计学意义，金元素浓度从高到低（40．0×10^-6、20．0×10^-6、10．0×10^-6、5．0×10^-6、2．5×10^-6），2组比较F值分别为191．876、265．419、77．987、52．061、18．745，P值均〈0．01。ICP—MS监测结果显示，GNRs@SiO2组细胞在孵育2、4、8、16、24h时细胞固体金元素含量分别为（256．7±3．3）、（602．8±2．4）、（1067．1±3．6）、（1998．5±4．3）、（2078．5±1．3）mg／kg，GNRs@Si02-FA组分别为（693．1±2．0）、（1432．0±2．6）、（2331．3±3．5）、（2484．5±5．0）、（2589．7±2．1）mg／kg，组间两两比较差异有统计学意义（F值分别为3278．070、34287．199、85434．870、18333．454、42412．973，P值均〈0．01），证明叶酸偶联的探针具有很强的靶向性。透射电镜观察到，GNRs@SiO2-FA与细胞共同培养1h后，细胞质内见少量纳米探针；4—24h，细胞质内见大量探针，但细胞核内未见。结论制备出的GNRs@SiO2-FA探针具有很好的生物安全性和靶向性。

Objective To develop a cancer cell targeting probe based on silica-coated gold nanorods and investigate its optics properties and its targeting effect on human hepatocellular carcinoma HepG2 cells in vitro. Methods Preparation of gold nanorods （GNRs） by seeded growth method, and then the spherical core-shell silica-coated gold nanorods were successfully prepared by a sol-gel method,finally the GNRs@ SiO2 was conjugated with folate （GNRs@ SiO2-FA）. The characteristics of GNRs@ SiO2-FA were studied using transmission electron microscopy, and UV spectra. The cells were divided into 2 groups randomly, adding GNRs@ SiO2-FA and GNRs solution respectively at the gold concentration of 40.0 × 10-6,20.0 × 10-6 ,10. 0 × 10-6,5.0 × 10-6,2. 5 × 10-6, and the MTr method was applied to detect the absorbance （A value） and study the cytotoxicity of GNRs@ SiOz-FA and GNRs. The cells were divided into 2 groups randomly, and incubated with the same concentration of GNRs @ SiO2-FA and GNRs @ SiO2 solution respectively,at 2,4,8,16,24 h,and the targeting of GNRs@ SiO2-FA cellular uptake were detected by ICP- MS by observing the process of GNRs@ SiO2-FA into the cells by transmission electron microscopy （TEM）. The data represented by x ± s ; single factor analysis of variance were compared between the 2 groups ; and the differences were significant when P 〈 0. 05. Results UV spectrum confirmed the successful preparation of GNRs@ SiO2-FA. The A value of the same concentration group was variance analysised, and the differences between the 2 groups was statistically significant （ all P 〈 0. 01 ） with the gold element concentration from high to low： F = 191. 876,265.419,77. 987,52. 061,18.745. The ICP-MS confirmed GNRs@ SiO2-FA could specifically bind with HepG2 cells. GNRs @ SiO2 group gold element content at 2,4,8, 16, 24 h was （256. 7 ± 3.3）, （602. 8 ± 2.4）, （ 1067. 1 ± 3.6）, （ 1998.5 ± 4. 3 ）, （ 2078. 5 ± 1.3 ） mg/kg and GNRs @ SiO2-FA group was（693.1 ± 2.0）, （ 1432. 0 ± 2. 6）, （2331.3 ± 3.5 ）, （2484. 5 ± 5.0）, （2589. 7 ± 2. 1 ） mg/kg,and the 2 groups was statistically significant （F =3278. 070, 34287. 199, 85434. 870, 18333. 454, 42412. 973 ,P 〈 0. 01 ）. TEM results showed that a small amount of nano probes were in the cytoplasm after cultured with GNRs@ SiO2-FA cells 1 h,and that ,a lot of probe were in the cytoplasm,4 -24 h later, but there was no probe in the nucleus. Conclusion The prepared Folate-conjugated gold nanorods has good performance on biocompatibility and targeting.