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Abstract：
SERS immunoassay biosensors hold immense potential for clinical diagnostics due to their high sensitivity and growing interest in multi-marker panels. However, their development has been hindered by difficulties in designing compatible extrinsic Raman labels. Prior studies have largely focused on spectroscopic characteristics in selecting Raman reporter molecules (RRMs) for multiplexing since the presence of well-differentiated spectra is essential for simultaneous detection. However, these candidates often induce aggregation of the gold nanoparticles used as SERS nanotags despite their similarity to other effective RRMs. Thus, an improved understanding of factors affecting the aggregation of RRM-coated gold nanoparticles is needed. Substituent electronic effects on particle stability were investigated using various para-substituted thiophenols. The inductive and resonant effects of functional group modifications were strongly correlated with nanoparticle surface charge and hence their stability. Treatment with thiophenols diminished the negative surface charge of citrate-stabilized gold nanoparticles, but electron-withdrawing substituents limited the magnitude of this diminishment. It is proposed that this phenomenon arises by affecting the interplay of competing sulfur binding modes. This has wide-reaching implications for the design of biosensors using thiol-modified gold surfaces. A proof-of-concept multiplexed SERS biosensor was designed according to these findings using the two thiophenol compounds with the most electron-withdrawing substitutions: NO2 and CN.
摘要：
SERS免疫测定生物传感器由于其高灵敏度和对多标记物组日益增长的兴趣而在临床诊断中具有巨大的潜力。然而,它们的发展受到设计兼容的外在拉曼标记的困难的阻碍。先前的研究主要集中在选择用于多路复用的拉曼报告分子（RRM）的光谱特性上，因为充分分化的光谱的存在对于同时检测至关重要。然而,尽管它们与其他有效的RRM相似，但这些候选物通常会诱导用作SERS纳米标签的金纳米颗粒的聚集。因此，需要更好地了解影响RRM包覆的金纳米粒子聚集的因素。使用各种对位取代的苯硫酚研究了取代基电子效应对颗粒稳定性的影响。官能团修饰的感应和共振效应与纳米颗粒表面电荷密切相关，因此与它们的稳定性密切相关。用苯硫酚处理减少了柠檬酸盐稳定的金纳米颗粒的负表面电荷，但是吸电子取代基限制了这种减少的幅度。建议这种现象是通过影响竞争性硫结合模式的相互作用而产生的。这对于使用硫醇改性的金表面的生物传感器的设计具有广泛的意义。根据这些发现，使用两种具有最吸电子取代基的苯硫酚化合物：NO2和CN，设计了概念验证的多路SERS生物传感器。
