标题： 细菌与金表面之间的静电相互作用和空间排斥的相互作用影响拉曼增强 显示英文标题

标题： Interplay of Electrostatic Interaction and Steric Repulsion between Bacteria and Gold Surface Influences Raman Enhancement

摘要： 等离激元纳米结构在光子学中有广泛的应用，包括通过表面增强拉曼光谱（SERS）进行病原体检测和诊断。尽管等离激元在信号增强中起着重要作用，但SERS中的静电作用仍未被完全理解并加以利用。在这里，我们对设计用于携带+29、+16、0和-9 mVζ电位的785 nm共振金纳米棒之间的静电相互作用进行了系统研究，覆盖了正电、中性和负电域。SERS活性在代表性革兰氏阴性大肠杆菌和革兰氏阳性表皮葡萄球菌上进行测试，这两种细菌在水中的ζ电位分别为-30和-23 mV。拉曼光谱和冷冻电子显微镜显示，+29、+16、0和-9 mV纳米棒对表皮葡萄球菌的SERS增强分别为7.2倍、3.6倍、4.2倍、1.3倍，对大肠杆菌的SERS增强分别为3.9倍、2.8倍、2.9倍、1.1倍。理论结果表明，静电作用是在所有相互作用力中决定细胞-纳米棒接近度和信号增强的主要因素。我们确定由于细胞突起引起的立体排斥是关键的对抗力。最后，提出了一种设计原则来估计SERS中的静电强度。我们的工作为细菌-纳米棒相互作用的原理提供了新见解，实现了可重复和精确的生物分子读数，这对下一代现场诊断和智能医疗应用至关重要。 显示英文摘要

摘要： Plasmonic nanostructures have wide applications in photonics including pathogen detection and diagnosis via Surface-Enhanced Raman Spectroscopy (SERS). Despite major role plasmonics play in signal enhancement, electrostatics in SERS is yet to be fully understood and harnessed. Here, we perform a systematic study of electrostatic interactions between 785 nm resonant gold nanorods designed to harbor zeta potentials of +29, +16, 0 and -9 mV spanning positive neutral and negative domains. SERS activity is tested on representative Gram-negative Escherichia coli and Gram-positive Staphylococcus epidermidis bacteria with zeta potentials of -30 and -23 mV respectively in water. Raman spectroscopy and Cryo-Electron microscopy reveal that +29, +16, 0 and -9 mV nanorods give SERS enhancement of 7.2X, 3.6X, 4.2X, 1.3X to Staphylococcus epidermidis and 3.9X, 2.8X, 2.9X, 1.1X to Escherichia coli. Theoretical results show that electrostatics play the major role among all interaction forces in determining cell-nanorod proximity and signal enhancement. We identify steric repulsion due to cell protrusions to be the critical opposing force. Finally, a design principle is proposed to estimate the electrostatic strength in SERS. Our work provides new insights into the principle of bacteria-nanorod interactions, enabling reproducible and precise biomolecular readouts, critical for next-generation point-of-care diagnostics and smart healthcare applications.