肉类新鲜度检测的荧光探针机理研究

Study on the Mechanism of Fluorescent Probes for Meat Freshness Detection

摘要: 本研究聚焦肉类新鲜度检测的荧光探针机理，以BM、BHM、BTH三种探针为研究对象。双描述符势计算显示，探针苯环上醛基和1,3-茚满二酮基团易与肉类腐败标志物尸胺(Cad)中NH₂发生亲电反应，醛基和1,3-茚满二酮基团为亲电位点、NH₂为亲核位点。BM、BHM因含单一反应基团，与尸胺反应生成链状BMP；BTH含双反应基团，与尸胺两端NH₂反应生成环状BTHP，且对尸胺检测限更低。激发态电子转移特性方面，BHM、BTH因1,3-茚满二酮吸电子效应，反应前呈电荷转移激发，反应后为局域激发，荧光波长从760 nm缩短至450 nm左右、颜色显著变化；BM反应前后均为局域激发，荧光及颜色变化不明显。电子态密度计算表明，引入1,3-茚满二酮基团改变探针轨道贡献，综合检出限与荧光变化，BTH是检测肉类新鲜度的最优候选荧光探针。

Abstract: This study focuses on the mechanism of fluorescent probes (BM, BHM, and BTH) for detecting meat freshness. Through the calculation of dual descriptor potentials, it is revealed that the aldehyde groups and 1,3-indanedione moieties on the benzene rings of these probes are prone to undergo electrophilic reactions with the NH₂ groups in cadaverine (Cad), a key marker of meat spoilage. BM and BHM, each containing a single reactive group (aldehyde or 1,3-indanedione), react with Cad to form the chain-like product BMP. In contrast, BTH, with both aldehyde and 1,3-indanedione groups, reacts with the NH₂ groups at both ends of Cad to generate the cyclic product BTHP, exhibiting a lower detection limit for Cad. Regarding the electron transfer characteristics in the excited state, due to the electron-withdrawing effect of the 1,3-indanedione group, BHM and BTH show charge-transfer excitation before the reaction, with a fluorescence wavelength of around 760 nm. After reacting with Cad, they switch to local excitation, and the fluorescence wavelength shortens to approximately 450 nm, accompanied by a distinct color change from red/orange to blue. However, BM, without a strong electron-withdrawing group, shows local excitation both before and after the reaction with Cad, resulting in an insignificant change in fluorescence wavelength (from 489 nm to 473 nm) and color. The calculation of the electronic state density indicates that the introduction of the 1,3-indanedione group alters the contribution of orbitals in the probes. Considering the detection limit of Cad and the degree of fluorescence (color) change, BTH is identified as the most suitable candidate fluorescent probe for detecting meat freshness, providing a theoretical basis for the design of efficient fluorescent probes for meat freshness detection.