基于多肽识别基团的荧光探针及其对食品中氰化物的检测

摘要

以7-二乙胺基香豆素-3-羧酸、甘氨酸、组氨酸为原料,采用标准多肽合成法成功合成了水溶性的荧光探针分子香豆素—甘氨酸-甘氨酸-组氨酸(Coumarin Gly-Gly-His,C-GGH),利用GGH三肽对Cu2+的络合作用形成C-GGH-Cu2+络合物,使探针分子C-GGH的荧光猝灭;然后,通过向体系中加入氰化物后,CN-对Cu2+的强络合作用形成稳定的络合物[Cu(CN)x]而使探针分子荧光逐渐恢复,以此实现对氰化物的定量检测.该法检测限为0.015 μmol/L,远低于国家标准(GB 8537-2008)中要求最严的矿泉水中氰化物的限量值0.01 mg/L(相当于摩尔浓度0.385 μmol/L),该探针分子对CN的检测不受SCN、F-、Cl-、Br-、I、PO43-、N3-、NO3-、AcO-、SO42-、Co32-等共存阴离子的影响.经对实际食物样品中氰化物进行检测,证明该方法的准确度与国标(GB/T 5009.48-2003、GB/T 5009.36-2003、GB/T8538-2008)方法一致,且更快捷、简单.%Cyanide is considered to be one of the most toxic species in food while the existing detection methods involve complex operation and will produce toxicity to inspectors.In this study,a water-soluble fluorescent probe(C-GGH) was synthesized by HOBT/DIC protocol in solution using 7 diethylaminocoumarin-3-carboxylic acid,Glycine and Histidine.Due to the presence of the recognition unit GGH,the probe C-GGH can conjugated with Cu2+ to formed non-fluorescent C-GGH-Cu2+complex.Due to the strong binding affinity of CN-to Cu2+,CN-can extract Cuz+ from C—GGH-Cu2+ complex,leading to the release of C-GGH and the recovery of fluorescent emission of the system.The probe allowed detection of cyanide in aqueous solution with a LOD (limit of detection) of 0.017 μmol/L which is much lower than the maximum contaminant level (0.385 μmol/L)for cyanide in mineral water set by national standard (GB 8537-2008).The probe also displayed excellent specificity for CN-towards other anions,including F-,Cl-,Br-,I-,SCN-,PO43-,N3-,NO3,AcO-,SO4242-,and CO32-.The method developed in this study received the same results as national standard method (GB/T 5009.48-2003,GB/T 5009.36-2003,GB/T 8538-2008),but more simple and quick in real sample detection.