以铱纳米团簇为标记，通过单细胞和激光剥蚀ICP-MS方法测定和定位ARPE-19细胞中的特定蛋白质

单细胞电感耦合等离子体质谱法（sc-ICP-MS）和激光剥蚀（LA）-ICP-MS互为补充，对在葡萄糖处理（100 mM，48 h）诱导氧化应激条件下的ARPE-19细胞中APOE和claudin-1的表达进行了全面研究。将测试结果与对照细胞进行比较。使用IrNC标记的特异性免疫探针依次通过ICP-MS测定这两种蛋白质，该方法可提供巨大的放大率（平均1760±90个Ir原子）。sc-ICP-MS分析使用新型样品引入系统microFAST Single Cell。该样品引入系统使ARPE-19细胞的细胞运输效率达到85±9%（使用PtNP标准为91± 5%）。在细胞悬浮液中使用特定IrNCs 免疫探针（sc-ICP-MS）进行适当的免疫细胞化学处理后，可获得单个ARPE-19 细胞中APOE和claudin-1的质量。 sc-ICP-MS对每个细胞的平均检出限为0.02 fg的APOE和3 ag的claudin-1。使用商业ELISA试剂盒验证了sc-ICP-MS获得的样品分析结果。LA-ICP-MS揭示了两种靶蛋白在单个细胞（固定在腔室壁上）中的分布。IrNCs免疫探针提供的高放大率可以识别单个ARPE-19细胞内的APOE和claudin-1。使用2×2μm的激光光斑获得高分辨率图像。

Single cell-inductively coupled plasma-mass spectrometry (sc-ICP-MS) and laser ablation (LA)-ICP-MS have been complementary employed to develop a comprehensive study of APOE and claudin-1 expression in ARPE-19 cells submitted to a glucose treatment (100 mM, 48 h) that induces oxidative stress conditions. Results were compared with control cells. The determination of the two proteins by ICP-MS was sequentially carried out using specific immunoprobes labelled with IrNCs that offer a huge amplification (1760±90 atoms of Ir on average). A novel sample introduction system, the microFAST Single Cell set-up, was employed for sc-ICP-MS analysis. This introduction system resulted in a cellular transport efficiency of 85 ± 9% for ARPE-19 cells (91±5% using a PtNPs standard). After the proper immunocytochemistry protocol with the specific IrNCs immunoprobes in cell suspensions (sc-ICP-MS), the mass of APOE and claudin-1 in individual ARPE-19 cells was obtained. Average detection limits per cell by sc-ICP-MS were 0.02 fg of APOE and 3 ag of claudin-1. The results of sample analyses obtained by sc-ICP-MS were validated with commercial ELISA kits. The distribution of both target proteins in individual cells (fixated in the chamber wall) was unveiled by LA-ICP-MS. The high amplification provided by the IrNCs immunoprobes allowed the identification of APOE and claudin-1 within individual ARPE-19 cells. High resolution images were obtained using a laser spot of 2 × 2 μm.