Detection and Determination of Mercury and Glutathione Based on the On-Off Fluorescence of Functionalized Metal-Organic-Framework as Nanosensor

Abstract: Metal-organic frameworks, called coordination polymers, are composed of building blocks such as organic ligands and metal ions that are joined by coordination bonds [۱]. The sensitive luminescence properties of MOFs have led to the development of sensor applications of LMOFs[۲]. In this study, a simple, selective, and sensitive fluorescence sensor based on the functionalized metal-organic-framework was designed for the detection and measurement of Hg۲+ and glutathione. The addition of Hg۲+ solution at pH = ۵.۰ to functionalized MOF resulted in the quenching of fluorescence at ۵۸۰ nm due to the interaction between Hg۲+ ion and sulfur-containing groups on MOF surface as well as electrostatic interaction. However, the addition of glutathione۲to this solution cause turn-on fluorescence due to the stronger interaction of this amino acid with mercury (II). Under optimal conditions, the calibration curve was linear in the concentration range of ۰.۰۰۱-۰.۴ nmol L-۱ for Hg۲+ with a coefficient of determination of R۲ = ۰.۹۹۷۶ and for glutathione in the range of ۱۰۰-۱۰۰۰ μmol L-۱ with a coefficient of determination of R۲ = ۰.۹۹۹۱. The limit of detection (LOD = ۳sb/m) and quantification (LOQ = ۱۰sb/m) for Hg۲+ was ۰.۰۰۰۳ nmol L-۱and ۰.۰۰۰۹ nmol L-۱ and for glutathione were ۲.۹۰ μmol L-۱ and ۹.۷۰ μmol L-۱, respectively. Inter-day and intra-day relative standard deviations (RSD%) for determination of (n = ۵) for mercury (II) (۰.۱ nmol L-۱) were ۲.۲ and ۴.۱% and for glutathione (۵۰.۰ μmol L-۱) were ۳.۲ and ۴.۲%, respectively. The method was successfully applied to the determination of mercury (II) in water samples and glutathione in biological samples.