Tumor necrosis factor alpha (TNF-α) is a cytokine with significance in early diagnosis of cardiovascular diseases, obesity and insulin resistance. We demonstrate the proof of concept for a rapid and sensitive detection of TNF-α using a magnetic bead pull-down assay in combination with surface-enhanced Raman scattering (SERS). The use of purified and highly SERS-active small clusters of gold nanoparticles (AuNP) provides the high sensitivity of the assay with a limit of detection of ca. 1 pg/mL. Continuous density gradient centrifugation was employed for separating the very bright silica-encapsulated AuNP dimers and trimers from the significantly weaker AuNP monomers. Negative control experiments with other cytokines (IL-6, IL-8) and bovine serum albumin (BSA) confirm the high specificity of the assay, but indicate also space for future improvements by further reducing non-specific binding between proteins and the SERS nanotags. The multiplexing potential of this SERS-based detection scheme is exemplarily demonstrated by using a set of three spectrally distinct and highly SERS-active AuNP clusters with unique spectral barcodes.

中文翻译：

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通过纯化和高度拉曼活性金纳米粒子簇的磁珠下拉测定法快速，灵敏的SERS检测细胞因子肿瘤坏死因子α（tnf-α）

肿瘤坏死因子α（TNF-α）是一种细胞因子，在心血管疾病，肥胖和胰岛素抵抗的早期诊断中具有重要意义。我们证明了结合磁珠下拉测定法和表面增强拉曼散射（SERS）进行快速灵敏的TNF-α检测的概念证明。金纳米颗粒（AuNP）的纯化和高SERS活性小簇的使用提供了测定的高灵敏度，并且对ca的检出限有限。1 pg / mL。连续密度梯度离心法用于将非常明亮的二氧化硅包裹的AuNP二聚体和三聚体与明显较弱的AuNP单体分离。其他细胞因子（IL-6，IL-8）和牛血清白蛋白（BSA）的阴性对照实验证实了该检测方法的高特异性，但也表明了通过进一步减少蛋白质与SERS纳米标签之间的非特异性结合来实现未来改进的空间。通过使用三个具有独特光谱条形码的光谱上不同且具有高度SERS活性的AuNP簇的集合，示例性地证明了这种基于SERS的检测方案的多路复用潜力。