Department of Physics, Mother Teresa Women's University, Kodaikanal, India.
UGC-DAE Consortium for Scientific Research, Indore, India.
Mater Sci Eng C Mater Biol Appl. 2019 Aug;101:431-437. doi: 10.1016/j.msec.2019.03.088. Epub 2019 Apr 2.
Label-free, sensitive, compatible and non-invasive nature of surface enhanced Raman spectroscopy (SERS) had substantially influenced various biological applications such as cell investigations, analysis of biomolecules such as DNA, RNA, proteins and detection of biomarkers for various diseases. This renders the engineering of bio-compatible, sensitive and efficient SERS substrates a necessity. In this study, the SERS activity of plasmonic silver nanospheres embedded ε-caprolactone/reduced graphite oxide nano layers (AGP) has been analyzed. The interactions of the nanolayers with nanospheres were evidenced by the broadening of the SPR band observed in UV-visible spectroscopy. Formation of AGP was further affirmed through X-ray diffraction patterns, X-ray photoelectron spectroscopy and the transmission electron microscopic images. Rhodamine 6G, a widely used SERS label for biological samples such as DNA and RNA sensing, protein screening, etc., was used here as the probing molecule to determine the efficiency of AGP as a SERS substrate. A low detection limit of 10 M was achieved with a calculated SERS enhancement factor of 1.2 × 10. The formation of 'hotspots' at the nanogaps between Ag nanospheres and the 'hot surfaces' on the nanolayers along with the efficient suppression of fluorescence, synergistically result in the enhanced Raman signals. This suggests the feasibility of developing AGP as a biocompatible, robust and efficient SERS substrate towards bio-sensing, molecule detection, etc.
表面增强拉曼光谱（SERS）具有无标记、高灵敏度、兼容性和非侵入性等特点，在细胞研究、生物分子如 DNA、RNA、蛋白质分析以及各种疾病生物标志物的检测等多个生物学领域得到了广泛应用。这使得工程化具有生物兼容性、高灵敏度和高效率的 SERS 基底成为必要。在本研究中，分析了等离子体银纳米球嵌入ε-己内酯/还原氧化石墨烯纳米层（AGP）的 SERS 活性。通过在紫外-可见光谱中观察到的 SPR 带的展宽，证明了纳米层与纳米球之间的相互作用。通过 X 射线衍射图谱、X 射线光电子能谱和透射电子显微镜图像进一步证实了 AGP 的形成。罗丹明 6G 是一种广泛用于生物样品如 DNA 和 RNA 传感、蛋白质筛选等的 SERS 标记物，这里用作探测分子，以确定 AGP 作为 SERS 基底的效率。通过计算得出的 SERS 增强因子为 1.2×10，实现了低至 10⁻⁶ M 的检测极限。Ag 纳米球之间的纳米间隙处形成的“热点”和纳米层上的“热点表面”，以及荧光的有效抑制，协同作用导致拉曼信号增强。这表明 AGP 作为一种生物相容性、坚固且高效的 SERS 基底，具有在生物传感、分子检测等方面进行开发的可行性。
