已有探针为什么不够用#

亚硫酸氢盐是食品中常见的防腐剂，也是体内含硫氨基酸代谢的产物，但过量与神经和心血管疾病相关。现有荧光探针各有短板：氢键识别易受微环境干扰，醛基亲核反应pH窗口窄，迈克尔加成易被生物硫醇干扰且识别后光谱蓝移，脱保护响应慢、灵敏度有限。本文要回答的是：能否利用席夫碱C=N键被HSO₃⁻特异性切断，做一种高信噪比的“开灯”检测，并系统解释取代基如何调控反应活性。

(a) UV−visible spectra of CME-OMe (10 μM) and CME-OMe (10 μM) + HSO3− (30 μM) in THF/H2O (v/v, 2/8). (b) Fluorescence spectra of CME-OMe (10 μM) and CME-OMe (10 μM) + HSO3− (30 μM) in THF/H2O (v/v, 2/8). (c) Bar graphs of fluorescence intensity for CME-OMe (10 μM) + different anions (30 μM) and CME-OMe (10 μM) + HSO3− (30 μM) + different anions (30 μM) in THF/H2O (v/v, 2/8): CO32−, S2−, HCO3−, SO32−, I−, PO43−, SO42−, CN−, ClO−, H2PO4−, NO3−, HPO42−, Ac−, Br−, SCN−, F−, HS−, NO2−, S2O32−, HSO3−, and CME-OMe. (d) Bar graph of fluorescence intensity for CME-OMe (10 μM) + HSO3− (30 μM) in THF/H2O (v/v, 2/8) at pH = 1−13, at 657 nm. (e) Scatter plot of fluorescence intensity vs time for CME-OMe (10 μM) + HSO3− (30 μM) in THF/H2O (v/v, 2/8) at 657 nm. (f) Fluorescence curve for CME-OMe (10 μM) + HSO3− (0−2.5 eq) in THF/H2O (v/v, 2/8). (g) Reaction mechanism diagram of HSO3− and CME-OMe. (h) Molecular frontier orbital diagram of CME-OMe and CME-OMe + HSO3−.

取代基怎么决定响应快慢#

作者合成了五个末端取代基不同的探针（CME-OMe、CME-OH、CME、CME-Tpe、CME-NO₂），均带AIE和近红外发射。HSO₃⁻亲核进攻C=N键使其断裂，释放强荧光的芳香胺片段，荧光从“关”变“开”。CME-OMe的甲氧基给电子，使亚胺氮电子密度最高，反应最快：t₉₀仅7.65秒，而CME-NO₂的硝基吸电子，t₉₀长达575.65秒。检出限为3.47×10⁻⁷ M，在pH 1–13范围内信号稳定，对41种干扰物保持选择性。NMR、HR-MS、IR和HPLC均确认产物为化合物A和B；理论计算显示反应后HOMO能级上移，共轭体系改变。实际样品中，水样回收率83.13%–103.20%，食品和中药材87.17%–102.21%；HeLa细胞和小鼠心、肝、肾切片中，加HSO₃⁻后红色荧光明显增强；APAP诱导的急性肝损伤模型中，损伤组肝组织荧光反而降低，作者解释为损伤肝内HSO₃⁻及其衍生物生成增多、与探针反应消耗所致。这些成像依赖外源或模型诱导的HSO₃⁻变化，原文未提供内源性水平的绝对定量。

(a) Cell survival rate bar graph for CME-OMe and CME-OMe + HSO3−(0−100 μM). (b) Confocal imaging of HeLa cells from top to bottom: CME-OMe (10 μM) and CME-OMe (10 μM) + HSO3− (5−20 μM). (c) Confocal fluorescence intensity bar graph. (d) Fluorescence imaging of mouse organ sections: from left to right, heart, liver, and kidney. From top to bottom: blank group, control group (CME-OMe), and experimental group (CME-OMe + HSO3−). (e) Liver organ imaging in a mouse liver injury model: from left to right: blank group (PBS), control group (PBS + CME-OMe), control group (APAP), and experimental group (APAP + CME-OMe). From top to bottom: three replicate experiments for each group. (f) Fluorescence intensity bar graph of the liver organ in a mouse liver injury model.

能用到哪一步#

这项工作把C=N键断裂做成一种可设计的识别开关，并用取代基电子效应把响应时间从近十分钟拉到七秒级，给食品安全快检和术中/活体成像提供了一条新思路。但所有应用仍停留在加标回收、细胞和小鼠模型层面，食品基质中的假阳性、探针在体内的代谢清除和长期毒性原文均未系统评估。它更像一个机理清晰、性能可调的探针平台，而不是已经可以直接部署的检测产品。