State Key Laboratory of Systems Medicine for Cancer, School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai 200030, PR China.
State Key Laboratory of Systems Medicine for Cancer, School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai 200030, PR China.
Spectrochim Acta A Mol Biomol Spectrosc. 2024 Dec 5;322:124852. doi: 10.1016/j.saa.2024.124852. Epub 2024 Jul 21.
Label-free surface-enhanced Raman spectroscopy (SERS) has attracted extensive attention as an emerging technique for molecular phenotyping of biological samples. However, the selective enhancement property of SERS mediated by complicated interactions between substrates and analytes is unfavorable for molecular profiling. The electrostatic force is among the most dominating interactions that can cause selective adsorption of molecules to charged substrates. This means if only negatively- or positively-charged SERS substrates are applied, then considerable SERS information from a portion of analytes would be lost, hindering comprehensive SERS sensing. In this work, we utilize both negatively- and positively-charged colloidal silver (Ag) nanoparticles (NPs) to detect various charged molecules. The negatively-charged citrate-stabilized Ag and the positively-charged Ag prepared via a cetyltrimethyl-ammonium chloride-based charge reversal protocol have been adopted as SERS substrates. The Ag NPs are all relatively well-dispersed with good uniformity. After applying the oppositely-charged NPs to the detection of charged molecules, we find the SERS results explicitly demonstrate the electrostatically-driven SERS selective enhancement, which is further supported and clarified by molecular electrostatic potential calculations. Our work highlights the importance of developing SERS substrates modified with appropriate surface charges for various analytes, and enlightens us that potentially more molecular SERS information can be acquired from complex bio-samples using combinations of oppositely-charged substrates.
无标记表面增强拉曼光谱（SERS）作为一种新兴的生物样本分子表型分析技术，受到了广泛关注。然而，基底与分析物之间复杂相互作用介导的 SERS 选择性增强不利于分子分析。静电力是最主要的相互作用之一，它会导致分子对带电荷的基底的选择性吸附。这意味着如果只使用带负电荷或带正电荷的 SERS 基底，那么一部分分析物的相当一部分 SERS 信息将会丢失，从而阻碍全面的 SERS 传感。在这项工作中，我们利用带负电荷和带正电荷的胶体银（Ag）纳米粒子（NPs）来检测各种带电荷的分子。采用带负电荷的柠檬酸盐稳定的 Ag 和通过十六烷基三甲基氯化铵基电荷反转协议制备的带正电荷的 Ag 作为 SERS 基底。Ag NPs 均具有良好的分散性和均匀性。将带相反电荷的 NPs 应用于带电荷分子的检测后，我们发现 SERS 结果明确表明静电驱动的 SERS 选择性增强，这通过分子静电势计算得到了进一步的支持和阐明。我们的工作强调了开发具有适当表面电荷的 SERS 基底用于各种分析物的重要性，并启发我们可以使用带相反电荷的基底组合从复杂的生物样本中获取更多的分子 SERS 信息。
