Radiation & Photochemistry Division, Bhabha Atomic Research Centre, Mumbai, India.
J Colloid Interface Sci. 2012 Aug 15;380(1):141-9. doi: 10.1016/j.jcis.2012.04.071. Epub 2012 May 9.
Surface-enhanced Raman scattering (SERS) study of tryptophan was carried out in silver hydrosol. The surface adsorption properties of tryptophan were investigated due to its biological importance. Tryptophan is an essential amino acid needed for the normal growth in infants and for nitrogen balance in adults. DFT calculations using B3LYP functional with LANL2DZ basis set was carried out to support the experimental Raman and SERS data. The strong enhancement of 1343 cm(-1) band, assigned to the CO(2) sym. stretching vibration in the SERS spectrum along with a red shift of 63 cm(-1), manifests that chemical mechanism contributes to the SERS activity. Moreover, the observed features in the SERS spectrum as well as theoretical calculations infer that tryptophan is chemisorbed to the silver surface directly through the oxygen and nitrogen atoms of the carboxylate and amino groups with an edge-on orientation with the indole ring lying nearly perpendicular to the silver surface. The SERS enhancement factors for various Raman vibrations of tryptophan were found to be of the order of 10(5)-10(6).
在银水溶胶中进行了色氨酸的表面增强拉曼散射（SERS）研究。由于色氨酸的生物重要性，研究了其表面吸附特性。色氨酸是婴儿正常生长和成人氮平衡所需的必需氨基酸。使用 B3LYP 函数和 LANL2DZ 基组进行了 DFT 计算，以支持实验拉曼和 SERS 数据。在 SERS 光谱中，强烈增强了 1343 cm(-1) 带，该带归因于 CO(2) sym。在 SERS 光谱中观察到的特征以及理论计算表明，化学机制有助于 SERS 活性。伸展振动，同时发生 63 cm(-1)的红移，表明化学机制有助于 SERS 活性。此外，在 SERS 光谱中观察到的特征以及理论计算表明，色氨酸通过羧酸盐和氨基中的氧和氮原子直接化学吸附到银表面上，具有与银表面几乎垂直的吲哚环的侧挂取向。色氨酸的各种拉曼振动的 SERS 增强因子被发现为 10(5)-10(6)的数量级。
