Department of Biomolecular Physics, Faculty of Physics, Babes-Bolyai University, M. Kogalniceanu Str. 1, 400084 Cluj-Napoca, Romania. Nanobiophotonics and Laser Microspectroscopy Center, Interdisciplinary Research Institute in Bio-Nano-Sciences, Babes-Bolyai University, T. Laurian Str. 42, 400271 Cluj-Napoca, Romania.
Nanotechnology. 2019 Aug 2;30(31):315701. doi: 10.1088/1361-6528/ab1857. Epub 2019 Apr 11.
This paper presents the fabrication and characterization of new gold-silver core-shell nanoparticles labeled with para-mercaptobenzoic acid (4MBA) molecules and demonstrates their use as surface-enhanced Raman spectroscopy (SERS)-nanotags with ultra-bright traceability inside cells and ability to convey spectrally-coded information about the intracellular pH by means of SERS. Unlike previous reported studies, our fabrication procedure includes in the first step the synthesis of chitosan-coated gold nanoparticles as a seed material with subsequent growing of a silver shell. The bimetallic core-shell structure is revealed by transmission electron microscopy, high-angle annular dark field scanning transmission electron microscopy, energy-dispersive x-ray elemental mapping and the presence of two interacting localized surface plasmon resonance modes in UV-vis extinction spectrum. The high SERS activity and sensitivity of as fabricated 4MBA-chit-Au-AgNPs nano-constructs to different pH in solution is investigated under 532 and 633 nm laser lines excitation. Next, in view of future studies in cancer diagnosis, the in vitro antiproliferative effects of SERS-nanotags against human ovarian adenocarcinoma cells (NIH:OVCAR-3) are evaluated. The capacity to operate as bright SERS nanotags with precise localization at a single cell level as well as intracellular pH indicators is clearly demonstrated by performing cell imaging under scanning confocal Raman microscopy.
本文介绍了新型金-银核壳纳米粒子的制备和表征，这些纳米粒子标记有对巯基苯甲酸（4MBA）分子，并展示了它们作为表面增强拉曼光谱（SERS）纳米标签的用途，具有超亮的细胞内示踪能力和通过 SERS 传递关于细胞内 pH 的光谱编码信息的能力。与之前报道的研究不同，我们的制备步骤包括在第一步合成壳聚糖包覆的金纳米粒子作为种子材料，随后生长银壳。通过透射电子显微镜、高角环形暗场扫描透射电子显微镜、能量色散 X 射线元素映射以及在紫外-可见消光光谱中存在两个相互作用的局域表面等离子体共振模式，揭示了这种双金属核壳结构。在 532nm 和 633nm 激光线激发下，研究了所制备的 4MBA-壳聚糖-Au-AgNPs 纳米结构在溶液中不同 pH 值下的高 SERS 活性和灵敏度。接下来，考虑到未来在癌症诊断方面的研究，评估了 SERS 纳米标签对人卵巢腺癌细胞（NIH：OVCAR-3）的体外增殖抑制作用。通过在扫描共聚焦拉曼显微镜下进行细胞成像，清楚地证明了它们作为明亮的 SERS 纳米标签的能力，具有精确的单细胞定位能力和细胞内 pH 指示剂的能力。
