双功能碳点用于葡萄糖的比色/比率荧光测定

Colorimetry/Ratio Fluorimetry Determination of Glucose with Bifunctional Carbon Dots

以生物质(合果芋叶片)、十二水合硫酸铁铵和脲为原料,采用水热法制备了铁、氮共掺杂碳点(Fe,N-CDs),采用透射电子显微镜和X射线光电子能谱对其形貌与元素组成进行了表征.该Fe,N-CDs既具有类过氧化物酶活性,也能在450 nm处产生强荧光发射.以Fe,N-CDs和邻苯二胺(OPD)为探针,建立了一种比色/比率荧光测定双氧水(H_(2)O_(2))的双信号方法.在H_(2)O_(2)存在下,Fe,N-CDs催化OPD氧化成黄色的2,3-二氨基吩嗪(DAP),DAP在420 nm处有1个特征吸收峰.在360 nm波长光的激发下,DAP在550 nm处有强荧光发射;由于荧光内滤效应,DAP又可猝灭Fe,N-CDs在450 nm处的荧光.基于此,DAP在420 nm处的吸光度(A_(420))及DAP与Fe,N-CDs的荧光强度比(I_(550)/I_(450))均可用于H_(2)O_(2)的定量分析.考虑到葡萄糖氧化酶能催化葡萄糖氧化生成H_(2)O_(2),进一步发展了一种比色/比率荧光双信号葡萄糖测定方法.在pH=5.4,温度40℃,1.75 mmol/L OPD及反应时间25 min的条件下,当葡萄糖浓度在1.0~100μmol/L范围内时,A_(420)及I_(550)/I_(450)值与浓度呈良好的线性关系,方法的检出限分别为0.8(比色)和0.6μmol/L(比率荧光).将该方法成功应用于人体血清中葡萄糖的测定.

Fe and N co-doped carbon dots(Fe,N-CDs)were prepared by hydrothermal method using biomass(leaf of syngonium podophyllum schott),ammonium ferric sulfate dodecahydrate and urea as raw materials,and their morphology and elemental composition were characterized by means of transmission electron micro-scopy(TEM)and X-ray photoelectron spectroscopy(XPS).The obtained Fe,N-CDs possessed both peroxidase-like activity and strong fluorescence emission at 450 nm.A dual signal(colorimetry and ratio fluorimetry)method for the determination ofH_(2)O_(2) was developed using Fe,N-CDs and o-phenylenediamine(OPD)as probe.WhenH_(2)O_(2) was present,OPD was oxidized to 2,3-diaminophenazine(DAP)under the catalysis of Fe,N-CDs.DAP had a characteristic absorption peak at 420 nm.When excited at 360 nm,DAP had a strong fluorescence emission at 550 nm,quenching the fluorescence of Fe,N-CDs at 450 nm because of the inner filter effect.Results showed that the concentration ofH_(2)O_(2) could not only affect the color of the DAP but also the fluorescence intensity of DAP and Fe,N-CDs.Thus,the absorbance of DAP at 420 nm(A420)and fluorescence intensity ratio of DAP and Fe,N-CDs(I550/I450)could be used for the quantitative analysis ofH_(2)O_(2).Considering that glucose oxidase can catalyze glucose oxidation to produceH_(2)O_(2),a colorimetric and ratio fluorescence dual-signal method for glucose detection was further developed.Under the conditions of pH 5.4,temperature 40℃,1.75 mmol/L OPD and reaction time 25 min,A420 and I550/I450 showed good linear relationship with the glucose concentration in the range of 1.0—100μmol/L,and the detection limits(LOD)for glucose were 0.8(colorimetry)and 0.6(ratio fluorimetry)μmol/L,respectively.This dual-signal method was applied to the determination of glucose in human serum with satisfactory results.