Fluolab【Angew.Chem.】陕西师范大学房喻院士、丁立平等|5ppb以下！臭氧触发COF薄膜开关，实现新精神活性物质的超灵敏检测
通讯作者： Ling-Ya Peng, Liping Ding, Yu Fang
文章概要
引言
新精神活性物质（NPS） 由于其结构多变、演变迅速且隐蔽性强，已成为全球公共安全和公共卫生的重大威胁。然而，这类物质在气相状态下的饱和蒸气压极低，且极易受到环境干扰（如水汽、二氧化碳等），导致现场快速、灵敏的监测技术一直面临巨大挑战。荧光薄膜传感器因其易于集成和高灵敏度而备受关注，但传统的薄膜材料往往存在有序性不足、活性位点分布不均等缺陷。针对这一痛点，陕西师范大学房喻院士团队开发了一种基于共价有机框架（COF） 的高性能荧光薄膜，通过独特的臭氧触发机制，为新精神活性物质的便携式实时检测提供了创新的技术方案。
(a) Representative methods for the preparation of fluorescent sensing films; (b) Structures of TTPA and TFPA, along with a schematic illustration of the preparation process for TTPA–TFPA COF membrane; (c) Schematic illustration of the response of TTPA–TFPA COF membrane to ozone, DMBA, and NH3.
主要实验及结论
研究人员通过界面限制聚合方法，结合后处理工艺，成功制备了由TTPA和TFPA单体构成的自支撑TTPA-TFPA COF薄膜。这种薄膜具有高度有序的孔道结构和优异的机械强度（杨氏模量达2.6 GPa）。实验发现，原始的COF薄膜发出绿色荧光，但在经过臭氧处理后，薄膜内部的亚胺键发生质子化，导致薄膜颜色变为浅红，荧光也相应红移至643 nm。这种“激活”后的薄膜在接触到模拟物DMBA蒸气时，荧光会迅速从红色切换回蓝色。质子化触发的荧光开关机制使得该传感器展现出极高的灵敏度，其检测限低至2.1 ppb，且响应时间缩短至1分钟以内。
Images and characterization of the TTPA–TFPA COF membrane. (a) COF membrane floating on water surface; (b) SEM image; (c) HRTEM image, with an inset showing the electron diffraction pattern obtained after FFT analysis and (d) AFM cross-sectional image of the COF membrane; (e) Raman spectra and (f) The solid-state 13CNMR spectrum of TTPA–TFPA COF membranes; (g) XRD pattern of the COF membrane, compared with that of the amorphous membrane and simulated stacking data; (h) N2 adsorption isotherms of the amorphous membrane and the COF membrane; (i) Pore size distribution of the COF membrane.
Visualization of the ozone treated TTPA–TFPA COF membrane's response to DMBA. (a) Fluorescence images and chromaticity coordinates, (b) absorption spectra, and (c) fluorescence emission spectra of the TTPA–TFPA COF membrane, ozone-treated COF membrane, and the membrane exposed to DMBA vapor after ozone treatment; (d) Colorimetric and fluorescence images for DMBA vapor detection at varying concentrations;(e) Plot of the (B+G)/R values extracted from the colorimetric and fluorescence images of the sensor membrane versus DMBA concentration.
Sensing performance of the ozone treated TTPA–TFPA COF membrane toward DMBA. (a) Photographs of the home-made portable DMBA sensor and a schematic of the sensor platform; (b) Photostability of the COF membrane after ozone treatment; (c) Responses of the COF membrane to DMBA and other common volatile gases, note: NTP denotes normal temperature and pressure (25°C, 1 atm) and error bars represent the standard deviation of three measurements; (d) Responses of the membrane to eight amines at a concentration of 333.3 ppm; (e) Response kinetics of the COF membrane to DMBA; (f) Membrane response to varying concentrations of DMBA vapor, and error bars represent the standard deviation of three measurements; (g) Durability test of the COF membrane (Concentration: 333.3 ppm, injection time: 30 s, recovery time: 60 s).
为了验证实际应用潜力，研究团队构建了一套便携式荧光传感平台。实验结果显示，该传感器对DMBA表现出卓越的选择性，能够排除酒精、乙酸、甲苯等常见干扰物。更重要的是，研究人员利用该系统对麻黄碱（EPH）、3-FEA、NENK等七种具有代表性的NPS参考标准品进行了测试。通过深入分析传感器在接触不同毒品分子时的动力学响应特性（如响应时间 和恢复时间 ），结合PCA主成分分析法，成功实现了对多种结构相似毒品分子的精准识别与区分。理论计算进一步证实，这种高性能的传感行为源于毒品分子与质子化COF框架之间强烈的氢键相互作用。
Mechanism of the membrane's response to DMBA. (a) XPS N 1s spectra of the TTPA–TFPA COF membrane, ozone-treated COF membrane, and the membrane exposed to DMBA-saturated vapor after ozone treatment. (b) Reduced density gradient (RDG) isosurface map of the protonated TTPA–TFPA COF fragment and DMBA. (c) Noncovalent interaction (NCI) analysis of the interaction between the protonated TTPA–TFPA COF fragment and DMBA. (d) Molecular orbitals involved in the S1 to S0 transitions of TTPA–TFPA COF membrane, ozone-treated COF membrane, and the membrane exposed to DMBA-saturated vapor after ozone treatment, along with the corresponding energy levels.
Ozone-treated TTPA–TFPA COF membrane for distinguishing seven secondary amine-based new psychoactive substances (NPS). (a) Schematic illustration of NPS vapor preparation. (b) Membrane response intensity to the seven NPS. (c) Kinetic response of the membrane to the seven NPS, with their molecular structures shown. (d) Logical decision-making process using fluorescence-based membrane detection to distinguish the seven NPS in unknown samples. (e) Three-dimensional PCA score plot for differentiating the seven NPS. (f) Electrostatic potential (ESP) values and (g) molecular size of the seven analyte molecules.
总结及展望
该研究不仅研制出一种超灵敏的自支撑COF荧光薄膜，还展示了其在复杂环境下进行现场快速筛查的巨大价值。这种基于臭氧激活和动力学分析的检测模式，为开发针对低挥发性化学毒物的便携式监控设备开辟了新路径。未来，该技术有望广泛应用于缉毒禁毒、公共场所安检以及临床药物监测等领域，为社会和谐稳定和人民生命健康提供坚实的技术保障。