Nanobiophotonics Center, Interdisciplinary Research Institute in Bio-Nano-Sciences and Faculty of Physics, Babes-Bolyai University, Cluj-Napoca, Romania.
Nanotechnology. 2012 Dec 7;23(48):485706. doi: 10.1088/0957-4484/23/48/485706. Epub 2012 Nov 9.
Surface-enhanced Raman scattering (SERS) nano-tags are of increasing interest in biomedical research as viable alternatives to bio-imaging techniques based on semiconductor quantum dots or fluorescent molecules. In this work, we fabricate silica-coated gold nanorods (AuNRs) encoded with two molecular labels to operate as highly effective spectroscopic nano-tags in near-infrared SERS (NIR-SERS) and surface-enhanced resonance Raman scattering combined with metal-enhanced fluorescence (SERRS-MEF), respectively. Specifically, a non-fluorescent molecule with strong affinity for a gold surface (para-aminothiophenol, p-ATP) and a common dye (Nile Blue, NB) with lower affinity have been successfully tested as NIR-SERS nano-tags under laser excitation at 785 nm. Moreover, as a result of designing AuNRs with a plasmon resonance band overlapping the electronic absorption band of the encoded NB molecule, a dual SERRS and MEF performance has been devised under resonant excitation at 633 nm. We explain this result by considering a partial desorption of NB molecules from the metal surface and their trapping into the silica shell at favorable distances to avoid quenching and enhance the fluorescence signal. Finally, we prove that the silica shell prevents the desorption or chemical transformation of p-ATP into p,p'-dimercaptoazobenzene species, as previously noticed, thus providing a highly stable SERRS signal, which is crucial for imaging applications.
表面增强拉曼散射(SERS)纳米标签在生物医学研究中越来越受到关注,它们是基于半导体量子点或荧光分子的生物成像技术的可行替代品。在这项工作中,我们制备了编码有两个分子标签的二氧化硅包覆的金纳米棒(AuNRs),分别作为近红外 SERS(NIR-SERS)和表面增强共振拉曼散射与金属增强荧光(SERRS-MEF)的高效光谱学纳米标签。具体来说,一种对金表面具有强亲和力的非荧光分子(对氨基苯硫酚,p-ATP)和一种亲和力较低的常见染料(尼罗蓝,NB)已成功作为 NIR-SERS 纳米标签进行了测试,在 785nm 激光激发下。此外,由于设计了等离子体共振带与编码 NB 分子的电子吸收带重叠的 AuNRs,因此在 633nm 共振激发下设计了双 SERRS 和 MEF 性能。我们通过考虑 NB 分子从金属表面部分解吸并在有利距离捕获到二氧化硅壳中来解释这一结果,以避免猝灭并增强荧光信号。最后,我们证明二氧化硅壳可以防止 p-ATP 解吸或化学转化为 p,p'-二巯基偶氮苯物种,如先前所注意到的,从而提供了对成像应用至关重要的高度稳定的 SERRS 信号。