Department of Chemistry, Sardar Vallabhbhai National Institute Technology, Surat, 395007, Gujarat, India.
Department of Zoology and Aquatic Animal Health Laboratory, C. Abdul Hakeem College, Melvisharam, 632509, Tamil Nadu, India.
Chem Biodivers. 2022 Sep;19(9):e202200425. doi: 10.1002/cbdv.202200425. Epub 2022 Aug 24.
An aggregation-induced emission (AIE) active Schiff base L was obtained by reacting pyridoxal and 2-hydroxy-1-naphthaldehyde with p-phenylenediamine in two simple steps. The colorimetric, UV/VIS and fluorescence studies of L revealed that the yellow emissive L (λ =540 nm, λ =450 nm) in pure DMSO turned to a red-emissive L, when the poor solvent fraction (HEPES buffer, 10 mM, pH 7.4) was increased above 50 % in DMSO. The SEM and DLS results indicated the formation of self-aggregates of L that restricted the intramolecular motion and promoted the excited state intramolecular proton transfer (ESIPT) process. The cations sensing ability of the AIEgen L was explored in HEPES buffer (5 % DMSO, 10 mM, pH 7.4), where Cu selectively quenched the fluorescence at 608 nm due to the chelation-enhanced fluorescence quenching (CHEQ) effect with an estimated sensitivity limit of 0.9 μM. Subsequently, the in situ formed AIEgen L-Cu complex was applied for the cascade detection of glutathione (GSH), cysteine (Cys) and homocysteine (Hcy). The decomplexation of Cu from the AIEgen L-Cu by GSH, Cys and Hcy restored the quenched fluorescence emission of AIEgen L at 608 nm. With this Cu displacement approach, the concentration of Cys, Hcy and GSH can be detected down to 2.8 μM, 3.12 μM and 2.0 μM, respectively. The practical utility of AIEgen L and AIEgen L-Cu was examined by monitoring the selective analytes in real environmental and biological samples, and also applied successfully for the cell imaging applications.
希夫碱 L 是由吡哆醛和 2-羟基-1-萘醛与对苯二胺在两步反应中得到的，具有聚集诱导发光（AIE）活性。L 的比色、紫外/可见和荧光研究表明，在纯 DMSO 中，黄色发光 L（λ=540nm，λ=450nm）在加入 DMSO 中不良溶剂分数（HEPES 缓冲液，10mM，pH7.4）超过 50%时转变为红色发光 L。SEM 和 DLS 结果表明，L 的自聚集形成限制了分子内运动，促进了激发态分子内质子转移（ESIPT）过程。AIE 试剂 L 的阳离子传感能力在 HEPES 缓冲液（5%DMSO，10mM，pH7.4）中进行了探索，其中 Cu 由于螯合增强荧光猝灭（CHEQ）效应而选择性猝灭 608nm 的荧光，估计其灵敏度极限为 0.9μM。随后，将原位形成的 AIE 试剂 L-Cu 复合物用于谷胱甘肽（GSH）、半胱氨酸（Cys）和同型半胱氨酸（Hcy）的级联检测。GSH、Cys 和 Hcy 从 AIE 试剂 L-Cu 中解络合 Cu，恢复 AIE 试剂 L 在 608nm 的猝灭荧光发射。通过这种 Cu 置换方法，可以检测到浓度低至 2.8μM、3.12μM 和 2.0μM 的 Cys、Hcy 和 GSH。通过监测实际环境和生物样品中的选择性分析物，对 AIE 试剂 L 和 AIE 试剂 L-Cu 的实际应用进行了检验，并且还成功地将其应用于细胞成像应用。
