Thatai Sheenam, Khurana Parul, Prasad Surendra, Kumar Dinesh
Department of Chemistry, Banasthali Vidyapith, Banasthali 304022, Rajasthan, India.
School of Biological and Chemical Sciences, Faculty of Science, Technology and Environment, The University of the South Pacific, Private Mail Bag, Suva, Fiji.
Talanta. 2015 Mar;134:568-575. doi: 10.1016/j.talanta.2014.11.024. Epub 2014 Nov 20.
The present study was structured to address development of an efficient devise for sensing of toxic Cd(2+) ions at trace level in aqueous media. In order to achieve this objective, the speckled core-shell nanocomposites (NCs) of silica-gold (SiO2@Au) using ~30 nm diameter of spherical gold nanoparticles (Au NPs) with 420 nm diameter of silica cores was synthesized. Au NPs showed the surface plasmon resonance (SPR) peak at 522 nm and spherical core-shell particles at 541 nm. Both Au NPs and SiO2@Au solutions were found to be sensitive to Cd(2+) ions in aqueous sample. The colour change occurred in presence of SiO2@Au at 0.1 ppm (100 ppb) of Cd(2+) ions whereas 2 ppm (2000 ppb) concentration of Cd(2+) ions was necessary for the colour change in Au NPs solution confirmed that SERS active SiO2@Au core-shell NCs 20 times more sensitive compared to Au NPs. The technique using SiO2@Au NCs is quantitative between 100 and 2000 ppb (0.1 to 2 ppm) while effective but non-quantitative above upto 10 ppm, the maximum concentration studied in present investigation. The detection limit using SiO2@Au NCs is 100 ppb (0.1 ppm) while Au NPs is able to detect Cd(2+) as low as 2000 ppb (2 ppm). The scanning electron microscopy (SEM) of Au NPs and SiO2@Au particles showed aggregation of Au NPs and SiO2@Au NCs in the presence of Cd(2+) ions. The surface enhanced Raman spectroscopy (SERS) was used to compare sensitivities of Au NPs and SiO2@Au towards Cd(2+) ions and confirmed that SiO2@Au core-shell NCs is 20 times more sensitive than Au NPs.
本研究旨在开发一种高效的装置，用于检测水介质中痕量水平的有毒镉（Cd(2+)）离子。为实现这一目标，合成了二氧化硅-金（SiO2@Au）的斑点核壳纳米复合材料（NCs），其使用直径约30nm的球形金纳米颗粒（Au NPs）和直径420nm的二氧化硅核。Au NPs在522nm处显示表面等离子体共振（SPR）峰，球形核壳颗粒在541nm处显示。发现Au NPs和SiO2@Au溶液对水性样品中的Cd(2+)离子均敏感。在Cd(2+)离子浓度为0.1ppm（100ppb）时，SiO2@Au存在下会发生颜色变化，而Au NPs溶液中颜色变化需要2ppm（2000ppb）的Cd(2+)离子浓度，这证实了具有表面增强拉曼散射（SERS）活性的SiO2@Au核壳NCs对Cd(2+)离子的敏感性是Au NPs的20倍。使用SiO2@Au NCs的技术在100至2000ppb（0.1至2ppm）之间是定量的，而在高达10ppm（本研究中研究的最大浓度）以上有效但非定量。使用SiO2@Au NCs的检测限为100ppb（0.1ppm），而Au NPs能够检测低至2000ppb（2ppm）的Cd(2+)。Au NPs和SiO2@Au颗粒的扫描电子显微镜（SEM）显示在Cd(2+)离子存在下Au NPs和SiO2@Au NCs发生聚集。使用表面增强拉曼光谱（SERS）比较了Au NPs和SiO2@Au对Cd(2+)离子的敏感性，证实了SiO2@Au核壳NCs比Au NPs敏感20倍。
