Dipicolinic acid (DPA) is a key biomarker of bacterial spores. In this study, we present a novel distance-based paper analytical device (d-PAD) for the fluorescence sensing of DPA. The detection mechanism relies on the complexation of ofloxacin (OFL) with Cu²⁺ ions, where Cu²⁺ quenches the fluorescence of OFL via static quenching. Upon the introduction of DPA, it interacts with the OFL-Cu²⁺ complex, resulting in an enhanced fluorescence signal from OFL. The assay demonstrated a limit of detection (LOD) of 0.08 μM over a range of 0.6–120 μM, as measured using a spectrofluorometer. The d-PAD was designed for efficient reagent transport through capillary action on paper substrates, allowing for rapid on-site DPA analysis without requiring advanced laboratory equipment. The length of the fluorescent bands on the d-PADs was proportional to the concentration of DPA, providing a simple and effective readout method. With a sensitivity of 0.6 μM, the device shows a strong response to varying DPA concentrations. This distance-based platform offers a straightforward and quantitative approach to result interpretation, making it a promising tool for detecting bacterial spores in real samples. The development and optimization of this paper-based microfluidic assay represent a significant step forward in portable diagnostic technologies.

中文翻译：

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一种基于长带荧光的纸张分析装置，用于通过氧氟沙星与 Cu2+ 络合检测二磷脂酸


二吡啶酸 （DPA） 是细菌孢子的关键生物标志物。在这项研究中，我们提出了一种用于 DPA 荧光传感的新型基于距离的纸张分析设备 （d-PAD）。检测机制依赖于氧氟沙星 （OFL） 与 Cu²⁺ 离子的络合，其中 Cu²⁺ 通过静态猝灭猝灭 OFL 的荧光。引入 DPA 后，它与 OFL-Cu²⁺ 复合物相互作用，导致 OFL 发出增强的荧光信号。该分析表明，使用荧光分光光度计测量，在 0.6–120 μM 范围内，检测限 （LOD） 为 0.08 μM。d-PAD 旨在通过毛细管作用在纸张基材上实现高效的试剂运输，无需先进的实验室设备即可进行快速的现场 DPA 分析。d-PADs 上荧光条带的长度与 DPA 的浓度成正比，提供了一种简单有效的读出方法。该装置的灵敏度为 0.6 μM，对不同的 DPA 浓度表现出强烈的响应。这种基于距离的平台提供了一种直接的定量结果解释方法，使其成为检测真实样品中细菌孢子的有前途的工具。这种基于纸张的微流控检测的开发和优化代表了便携式诊断技术向前迈出的重要一步。