Nanobiophotonics and Laser Microscopy Center, Interdisciplinary Research in Bio-Nano-Sciences, and Faculty of Physics, Babes-Bolyai University, Treboniu Laurian Street 42, 400271 Cluj-Napoca, Romania.
Nanotechnology. 2012 Feb 10;23(5):055501. doi: 10.1088/0957-4484/23/5/055501. Epub 2012 Jan 11.
Surface-enhanced Raman spectroscopy (SERS) is a technique that has become widely used for identifying and providing structural information about molecular species in low concentration. There is an ongoing interest in finding optimum particle size, shape and spatial distribution for optimizing the SERS substrates and pushing the sensitivity toward the single-molecule detection limit. This work reports the design of a novel, biocompatible SERS substrate based on small clusters of anisotropic silver nanoparticles embedded in a film of chitosan biopolymer. The SERS efficiency of the biocompatible film is assessed by employing Raman imaging and spectroscopy of adenine, a significant biological molecule. By combining atomic force microscopy with SERS imaging we find that the chitosan matrix enables the formation of small clusters of silver nanoparticles, with junctions and gaps that greatly enhance the Raman intensities of the adsorbed molecules. The study demonstrates that chitosan-coated anisotropic silver nanoparticle clusters are sensitive enough to be implemented as effective plasmonic substrates for SERS detection of nonresonant analytes at the single-molecule level.
表面增强拉曼光谱（SERS）是一种广泛用于识别和提供低浓度分子物种结构信息的技术。人们一直致力于寻找最佳的颗粒尺寸、形状和空间分布，以优化 SERS 基底，并将灵敏度推向单分子检测极限。本工作报道了一种基于壳聚糖生物聚合物薄膜中嵌入各向异性银纳米粒子簇的新型生物相容性 SERS 基底的设计。通过对腺嘌呤这一重要生物分子的拉曼成像和光谱分析，评估了生物相容性薄膜的 SERS 效率。通过原子力显微镜与 SERS 成像相结合，我们发现壳聚糖基质能够形成银纳米粒子的小簇，其中的连接和间隙极大地增强了吸附分子的拉曼强度。该研究表明，壳聚糖包覆的各向异性银纳米粒子簇具有足够的灵敏度，可以用作非共振分析物的 SERS 检测的有效等离子体基底，在单分子水平上实现。
