Bai Shi, Hu Anming, Hu Youjin, Ma Ying, Obata Kotaro, Sugioka Koji
Advanced Laser Processing Research Team, RIKEN Center for Advanced Photonics, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.
Department of Mechanical, Aerospace and Biomedical Engineering, University of Tennessee Knoxville, 1512 Middle Drive, Knoxville, TN 37996, USA.
Nanomaterials (Basel). 2022 Mar 15;12(6):970. doi: 10.3390/nano12060970.
Surface-enhanced Raman scattering (SERS) enables trace-detection for biosensing and environmental monitoring. Optimized enhancement of SERS can be achieved when the energy of the localized surface plasmon resonance (LSPR) is close to the energy of the Raman excitation wavelength. The LSPR can be tuned using a plasmonic superstructure array with controlled periods. In this paper, we develop a new technique based on laser near-field reduction to fabricate a superstructure array, which provides distinct features in the formation of periodic structures with hollow nanoclusters and flexible control of the LSPR in fewer steps than current techniques. Fabrication involves irradiation of a continuous wave laser or femtosecond laser onto a monolayer of self-assembled silica microspheres to grow silver nanoparticles along the silica microsphere surfaces by laser near-field reduction. The LSPR of superstructure array can be flexibly tuned to match the Raman excitation wavelengths from the visible to the infrared regions using different diameters of silica microspheres. The unique nanostructure formed can contribute to an increase in the sensitivity of SERS sensing. The fabricated superstructure array thus offers superior characteristics for the quantitative analysis of fluorescent perfluorooctanoic acid with a wide detection range from 11 ppb to 400 ppm.
表面增强拉曼散射（SERS）可用于生物传感和环境监测中的痕量检测。当局域表面等离子体共振（LSPR）的能量接近拉曼激发波长的能量时，可实现SERS的优化增强。可以使用具有可控周期的等离子体超结构阵列来调节LSPR。在本文中，我们开发了一种基于激光近场还原的新技术来制造超结构阵列，该技术在形成具有空心纳米团簇的周期性结构方面具有独特的特征，并且比现有技术以更少的步骤灵活控制LSPR。制造过程包括将连续波激光或飞秒激光照射到自组装二氧化硅微球的单层上，通过激光近场还原沿着二氧化硅微球表面生长银纳米颗粒。使用不同直径的二氧化硅微球，可以灵活调节超结构阵列的LSPR，以匹配从可见光到红外区域的拉曼激发波长。形成的独特纳米结构有助于提高SERS传感的灵敏度。因此，制造的超结构阵列具有卓越的特性，可用于对荧光全氟辛酸进行定量分析，检测范围从11 ppb到400 ppm。
