Long Yu,Qutong Zheng,Heng Wang,Chenxi Liu,Xiaoqing Huang,Yuxiu Xiao
Water is one of the most widespread impurities and contaminants for pharmaceuticals and chemical products. A simple, fast and reliable water assay method is of high significance for the pharmaceutical and chemical manufacturing industries. In this work, lanthanide metal–organic framework Eu-dipicolinic acid/2-aminophthalic acid (Eu-DPA/PTA-NH2) was prepared as a double-color ratiometric fluorescent water sensor, which shows ultrasensitive (limit of detection 0.01% v/v) and linear broad-range (0–100% v/v) response to water. An innovative analytical device based on a one-to-two logic gate was constructed by using the water content and the two fluorescence responses as the input and output signals, respectively. The direct analysis of water content can be achieved by the four output types, NOT (0, 1), PASS 0 (0, 0), PASS 1 (1, 1), and YES (1, 0). Importantly, the metal–organic framework (MOF)-loaded fiber paper was prepared as a microsensor, and a water assay tube was designed for rapid water detection of solid pharmaceuticals via ratiometric chromaticity, coupled with a portable visual determination device. The paper-based microsensor is response-rapid (20 s), long-term stable (at least 30 days), and can achieve the accurate (relative error <9.8%) visual assay of trace water in solid pharmaceuticals. To our knowledge, this is the first time to report an MOF-based double-color ratiometric fluorescent water sensor, a water analytical logic device, and a paper-based water microsensor for point-of-care visual water assay in solid samples via ratiometric chromaticity.
We synthesized blue fluorescent carbon quantum dots (CDs) by the solvothermal strategy using 2,5-dihydroxyterephthalic acid as the precursor. The as-prepared CD surfaces contain abundant carboxyl and hydroxyl groups and show excitation-independent emission and excellent chemical stability. Interestingly, with the increment of water contents in organic solvents, the CDs underwent a visual fluorescence color transition from blue to green, which could be attributed to the excited-state intramolecular proton transfer effect via the intermolecular hydrogen bonding between CDs and water. Based on this, we designed an effective ratiometric fluorescence water sensor in organic solvents, which featured self-calibration, visualization, rapid response (<20 s), and high sensitivity (limit of detection = 0.052%, v/v, in ethanol). The smartphone-based quantitative assay was also realized using CD-loaded paper strips through a color processing application and successfully applied to monitor the water content in spirit samples. Humidity sensing was further evaluated through the as-prepared CDs/polymer films. Remarkably, the CD-based sensors were well recyclable both with paper strips and polymer films. The as-prepared CDs also hold great potential for anticounterfeiting.
危险品化学品经营许可证（带存储）