Centro de Ciências Naturais e Humanas, Universidade Federal do ABC, Santo André, SP, Brazil.
PLoS One. 2013 Sep 3;8(9):e73701. doi: 10.1371/journal.pone.0073701. eCollection 2013.
In this proof-of-concept study, we describe the use of the main red beet pigment betanin for the quantification of calcium dipicolinate in bacterial spores, including Bacillus anthracis. In the presence of europium(III) ions, betanin is converted to a water-soluble, non-luminescent orange 1∶1 complex with a stability constant of 1.4 × 10(5) L mol(-1). The addition of calcium dipicolinate, largely found in bacterial spores, changes the color of the aqueous solution of [Eu(Bn)(+)] from orange to magenta. The limit of detection (LOD) of calcium dipicolinate is around 2.0 × 10(-6) mol L(-1) and the LOD determined for both spores, B. cereus and B. anthracis, is (1.1 ± 0.3)× 10(6) spores mL(-1). This simple, green, fast and low cost colorimetric assay was selective for calcium dipicolinate when compared to several analogous compounds. The importance of this work relies on the potential use of betalains, raw natural pigments, as colorimetric sensors for biological applications.
在这项概念验证研究中，我们描述了主要的红甜菜色素甜菜红素在定量细菌孢子（包括炭疽芽孢杆菌）中的二价钙离子二吡咯烷酮酸方面的应用。在铕(III)离子存在下，甜菜红素转化为一种水溶性、非发光的橙色 1:1 配合物，其稳定常数为 1.4×10(5)L mol(-1)。大量存在于细菌孢子中的二价钙离子二吡咯烷酮酸的加入会使[Eu(Bn)(+)]水溶液的颜色从橙色变为品红色。二价钙离子二吡咯烷酮酸的检测限（LOD）约为 2.0×10(-6)mol L(-1)，对于芽孢杆菌和炭疽芽孢杆菌两种孢子，LOD 值分别为（1.1±0.3）×10(6)孢子 mL(-1)。与几种类似化合物相比，这种简单、绿色、快速且低成本的比色测定法对二价钙离子二吡咯烷酮酸具有选择性。这项工作的重要性在于甜菜红素，即原始天然色素，作为生物应用的比色传感器的潜在用途。
