近日，日本大阪大学的Takeo Minamikawa&Mitsuo Kawasaki及其研究团队取得一项新进展。经过不懈努力，他们利用柱状结构二氧化硅覆盖层保护银纳米岛实现荧光和拉曼光谱的长程增强。相关研究成果已于2024年10月28日在国际知名学术期刊《光：科学与应用》上发表。

该研究团队展示了使用厚度超过100纳米的柱状结构二氧化硅（CSS）覆盖层包覆的密集随机银纳米岛（AgNIs）阵列，实现了荧光和拉曼散射的长程增强，即远程类等离子体增强（RPE）。CSS层提供了物理和化学保护，减少了分析物分子与金属纳米结构之间的影响。RPE板通过溅射和化学浸泡在金（I）/卤化物溶液中高效制备。

即使分析物分子与金属纳米结构不接近，RPE板也能显著增强拉曼散射和荧光。拉曼散射的最大增强因子为10⁷倍，荧光的最大增强因子为10²倍。RPE已成功应用于增强HeLa细胞内信号转导动力学的荧光生物传感和食管组织的拉曼组织学成像。这一发现与传统的近场增强理论存在有趣的偏差，因为该理论框架无法轻易解释这些发现。

然而，根据研究人员所展示的现象学方面，观察到的增强可能与AgNIs的局域表面等离激元与分析物分子跃迁偶极子之间通过CSS结构实现的远程共振耦合有关。尽管需要进一步研究以充分了解其潜在机制，但RPE板具有高生产率和生物相容性等实际优势，是化学、生物学和医学领域生物传感和生物分子分析的有价值工具。研究人员预计，RPE将作为一种多功能分析工具，在各种生物学背景下通过拉曼和荧光分析实现增强的生物传感。

附：英文原文

Title: Long-range enhancement for fluorescence and Raman spectroscopy using Ag nanoislands protected with column-structured silica overlayer

Author: Minamikawa, Takeo, Sakaguchi, Reiko, Harada, Yoshinori, Tanioka, Hiroki, Inoue, Sota, Hase, Hideharu, Mori, Yasuo, Takamatsu, Tetsuro, Yamasaki, Yu, Morimoto, Yukihiro, Kawasaki, Masahiro, Kawasaki, Mitsuo

Issue&Volume: 2024-10-28

Abstract: We demonstrate long-range enhancement of fluorescence and Raman scattering using a dense random array of Ag nanoislands (AgNIs) coated with column-structured silica (CSS) overlayer of over 100nm thickness, namely, remote plasmonic-like enhancement (RPE). The CSS layer provides physical and chemical protection, reducing the impact between analyte molecules and metal nanostructures. RPE plates are fabricated with high productivity using sputtering and chemical immersion in gold(I)/halide solution. The RPE plate significantly enhances Raman scattering and fluorescence, even without proximity between analyte molecules and metal nanostructures. The maximum enhancement factors are 10⁷-fold for Raman scattering and 10²-fold for fluorescence. RPE is successfully applied to enhance fluorescence biosensing of intracellular signalling dynamics in HeLa cells and Raman histological imaging of oesophagus tissues. Our findings present an interesting deviation from the conventional near-field enhancement theory, as they cannot be readily explained within its framework. However, based on the phenomenological aspects we have demonstrated, the observed enhancement is likely associated with the remote resonant coupling between the localised surface plasmon of AgNIs and the molecular transition dipole of the analyte, facilitated through the CSS structure. Although further investigation is warranted to fully understand the underlying mechanisms, the RPE plate offers practical advantages, such as high productivity and biocompatibility, making it a valuable tool for biosensing and biomolecular analysis in chemistry, biology, and medicine. We anticipate that RPE will advance as a versatile analytical tool for enhanced biosensing using Raman and fluorescence analysis in various biological contexts.

DOI: 10.1038/s41377-024-01655-3

Source: https://www.nature.com/articles/s41377-024-01655-3