Department of Chemistry, University of Warsaw, Pasteur Street 1, 02-093 Warsaw, Poland.
Analyst. 2014 Mar 7;139(5):1101-11. doi: 10.1039/c3an01197f.
We report the first use of 3-amino-5-mercapto-1,2,4-triazole (AMT) to construct a surface-enhanced Raman scattering (SERS) based pH nano- and microsensor, utilizing silver nanoparticles. We optimize the procedure of homogenous attachment of colloidal silver to micrometer-sized silica beads via an aminosilane linker. Such micro-carriers are potential optically trappable SERS microprobes. It is demonstrated that the SERS spectrum of AMT is strongly dependent on the pH of the surroundings, as the transformation between two different adsorption modes, upright (A form) and lying flat (B form) orientation, is provoked by pH variation. The possibility of tuning the nanosensor working range by changing the concentration of AMT in the surrounding solution is demonstrated. A strong correlation between the pH response of the nanosensor and the AMT concentration in solution is found to be controlled by the interactions between the surface and solution molecules. In the absence of the AMT monomer, the performance of both the nano- and microsensor is shifted substantially to the strongly acidic pH range, from 1.5 to 2.5 and from 1.0 to 2.0, respectively, which is quite unique even for SERS-based sensors.
我们首次报道了利用 3-氨基-5-巯基-1,2,4-三唑（AMT）构建基于表面增强拉曼散射（SERS）的 pH 值纳米和微传感器，该传感器利用了银纳米粒子。我们优化了通过氨基硅烷连接剂将胶体银均匀附着到微米级硅珠上的过程。这样的微载体是潜在的可光学捕获的 SERS 微探针。结果表明，AMT 的 SERS 光谱强烈依赖于周围环境的 pH 值，因为两种不同的吸附模式（垂直（A 型）和水平（B 型）取向）之间的转变是由 pH 值变化引起的。通过改变周围溶液中 AMT 的浓度来调节纳米传感器工作范围的可能性得到了证明。还发现纳米传感器的 pH 值响应与溶液中 AMT 浓度之间存在很强的相关性，这是由表面和溶液分子之间的相互作用控制的。在没有 AMT 单体的情况下，纳米传感器和微传感器的性能都显著向强酸性 pH 值范围移动，分别从 1.5 到 2.5 和从 1.0 到 2.0，即使对于基于 SERS 的传感器来说，这也是非常独特的。
