AbstractEuropium(III)-doped carbon dots (Eu-CDs) were prepared from citric acid and europium nitrate via a one-pot pyrolytic method. The Eu-CDs emit intense blue fluorescence (with excitation/emission peaks at 365/465 nm), are water soluble and biocompatible. On addition of 2,6-dipicolinic acid (DPA; an anthrax biomarker), ligand-to-ion energy transfer occurs from DPA to Eu(III) which has a red emission peaking at 615 nm. This results in an increase of the intensity of the red fluorescence. DPA can be detected by the ratio of fluorescence intensities at 616 and 475 nm. The method has an analytical range that extends from 5 to 700 nmol·L−1, with a 5 nmol·L−1 detection limit. The Eu-CDs also were incorporated into a test paper for visual detection of DPA with a portable UV lamp and a smartphone. In this case, the detection limit is 1 μmol·L−1. The Eu-CDs internalize well into HeLa cells, and this paves the way to bioimaging. Graphical abstractSchematic of a method for visual detection of 2,6-dipicolinic acid (DPA, an anthrax biomarker) by using a test stripe impregnated with europium(III)-doped carbon dots (Eu-CDs).

中文翻译：

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通过在测试条中使用掺铕 (III) 的碳点，比色法测定炭疽生物标志物 2,6-吡啶二羧酸

摘要 以柠檬酸和硝酸铕为原料，通过一锅热解法制备了掺铕(III)的碳点(Eu-CDs)。Eu-CD 发出强烈的蓝色荧光（激发/发射峰位于 365/465 nm），具有水溶性和生物相容性。添加 2,6-吡啶二羧酸（DPA；炭疽生物标志物）后，配体到离子的能量转移发生从 DPA 到 Eu(III)，其红色发射峰值为 615 nm。这导致红色荧光强度的增加。DPA 可以通过 616 和 475 nm 处的荧光强度比来检测。该方法的分析范围从 5 到 700 nmol·L-1，检测限为 5 nmol·L-1。Eu-CDs 也被整合到一张试纸中，用于使用便携式紫外线灯和智能手机对 DPA 进行视觉检测。在这种情况下，检测限为 1 μmol·L-1。Eu-CDs 很好地内化到 HeLa 细胞中，这为生物成像铺平了道路。图形摘要使用浸有铕 (III) 掺杂碳点 (Eu-CD) 的测试条对 2,6-吡啶二羧酸（DPA，一种炭疽生物标志物）进行视觉检测的方法示意图。