The Synthesis And Research Of Water-Soluble Sulfhydryl Probe Based On Aromatic-Fused Imidazole

Recently years, due to high selectivivty and sensitivity, low concentration of detectionlimit and easy detection operation methods, fluorescent probes have been widely applied todetect various ions in living organisms. More attention was focused on synthesis offluorescent compounds, which makes detecting ions more efficient and more convenient.Based on the principle of fluorescent probes’s design and synthesis, we synthesized two kindsof transition-metal complexes as fluorescent probes, which exhibit highly water-soluble.Thiols are an important component of many proteins and small molecules in organismsand play an important role in the antioxidant system in biological system. Such as glutathione（GSH）, cysteine （Cys） and homocysteine （Hcy） . Thiols play an important role in maintainingbiological redox homeostasis. They also play a crucial role in metabolic pathways. The levelsof certain thiols have been linked to some diseases.In this paper, two kinds of aromatic-fused imidazole sulfhydryl fluorescent probes weredesigned, which exhibit highly water-soluble. We synthesized HPBI-based compounds of2-[5′-（N, N-dimethyl-N-dodecyl ammonium chloride）-acetamide-2′-hydroxyphenyl] benzimidazole （DMDACA-HPBI）, Which was added long-chain carbon group and trimethyl ammonium chloride group. We also synthesized NIP-based compound of 4-（trimethyl ammoniumchloride）-acetamide-2-（1H-naphtho[2,3-d]imidazol-2-yl） phenol （TMACA-NIP）. Various metal ions were added into the fluorescent compounds solution respectively. It found that Cu²⁺quenched the fluorescence of compounds most efficiently by measured UV absorptionspectrum and fluorescence emission spectrum of the solution.Next, we examined the UV absorption spectrum and fluorescence emission spectrum ofthe probe with Cu²⁺in the presence of thiols, such as glutathione （GSH）, L-Cysteine MethylEster Hydrochloride （L-Cys）, mercaptoethylamine hydrochloride （MEA）, thioglycolic acid（TGA）. It found that, the fluorescence emission intensity increased rapidly only after addingGSH into aqueous solutions of fluorescence compound and Cu²⁺. In addition, the water-solubility of fluorescence probes were improved by added quaternary ammonium salt groups.It’s helpful to measure of GSH levels in biological systems.