Baig Mirza Muhammad Fahad, Chen Yu-Chie
Department of Applied Chemistry, National Chiao Tung University, 1001 University Road, Hsinchu, 300, Taiwan.
Anal Bioanal Chem. 2018 Feb;410(6):1805-1815. doi: 10.1007/s00216-017-0836-2. Epub 2018 Jan 24.
Dipicolinic acid (DPA) can cause neurotoxicity and is abundant in bacterial spores. Although analytical methods have been reported for DPA detection with high sensitivity, their selectivity toward DPA is declined greatly in the presence of phosphates in the samples. In this study, we developed an approach for DPA detection that is not affected by the presence of phosphates. A colorimetric method based on the use of gold nanoparticles (AuNP) complexed with Ca as sensing agents was explored for DPA detection. Calcium ions and glutathione-capped gold nanoparticles (AuNPs@GSH) can easily form complexes (Ca-AuNP@GSH) through GSH-Ca chelation, leading to the aggregation of AuNPs@GSH. The aggregation resulting from the complexes of AuNPs@GSH and Ca can be reversed with the addition of DPA owing to the high formation constant (log K = 4.4) between DPA and Ca. Furthermore, the color of AuNPs@GSH changes from red to purple when complexed with Ca, returning to red upon addition of DPA. The limit of detection of this sensing method toward DPA was estimated to be as low as ~ 2 μM. The feasibility of using the sensing method for quantitative detection of DPA in soil and Bacillus cereus spore samples was also demonstrated. Graphical abstract A AuNP-based colorimetric sensing method against dipicolinic acid is developed.
吡啶二羧酸（DPA）可导致神经毒性，且在细菌孢子中含量丰富。尽管已有报道称一些分析方法可实现对DPA的高灵敏度检测，但在样品中存在磷酸盐的情况下，这些方法对DPA的选择性会大幅下降。在本研究中，我们开发了一种不受磷酸盐存在影响的DPA检测方法。探索了一种基于使用与钙络合的金纳米颗粒（AuNP）作为传感剂的比色法用于DPA检测。钙离子和谷胱甘肽包覆的金纳米颗粒（AuNPs@GSH）可通过谷胱甘肽-钙螯合轻松形成络合物（Ca-AuNP@GSH），导致AuNPs@GSH聚集。由于DPA与钙之间具有较高的形成常数（log K = 4.4），加入DPA后可使由AuNPs@GSH与钙形成的络合物导致的聚集发生逆转。此外，AuNPs@GSH与钙络合时颜色从红色变为紫色，加入DPA后又恢复为红色。该传感方法对DPA的检测限估计低至约2 μM。还证明了使用该传感方法对土壤和蜡样芽孢杆菌孢子样品中的DPA进行定量检测的可行性。图形摘要：开发了一种基于AuNP的针对吡啶二羧酸的比色传感方法。
