Research On Mercury Ion Detection Method Based On Gold Nanoclusters And Porphyrin

Mercury ion is one of the most common toxic heavy metal ions.Mercury ion is persistent,easy to trasfer,and cannot be degraded.Mercury ion is accumulated in the body,thus causing irreparable and irreversible damage to the nervous system and kidney of the human body.Therefore,it is of great significance to construct simple,rapid and sensitive methods to detect mercury ions in practical samples.Part one.Ratiometric fluorometric method detection of mercury ion based on its quenching effect on tetraphenylporphyrin tetrasulfonic acid modified gold nanoclustersHere a ratiometric fluorescence nanosensing platform was developed for sensitive detection of mercury(?)ion by using glutathione-stabilized gold nanoclusters(GSH-AuNCs)/tetraphenylporphyrin tetrasulfonic acid(TPPS)nanocomposites in an aqueous environment.The formation of GSH-AuNC/TPPS nanocomposites was verified by significant change of absorption intensity and red-shift of emission peak of TPPS.The GSH-AuNC/TPPS nanocomposites have dual emission peaks centering at 572 nm and 664 nm under single excitation wavelength at 365 nm.Mercury(?)ion intensively quenches the fluorescence of GSH-AuNCs at 572 nm and has a negligible influence on that of TPPS at 664 nm.The decrease amplitude of the relative fluorescence intensities is linearly dependent on the concentration of mercury(?)ion in the range of 0.02-2.0?mol/L with a detection limit of 7 nmol/L(3Sb/S).The relative standard deviation was 2.0%at 0.5?mol/L mercury(?)ion concentration level(n=11).The method was successfully applied to the determination of mercury(?)ion in water samples with recoveries within the range of 87.5%-107.5%.Part two.Ratiometric fluorometric method detection of mercury ion based on inactivating peroxide mimicking enzyme and quenching fluorescence of gold nanoclustersGold nanoclusters ftonction as a peroxide mimicking enzyme which can catalyze the color reaction between 3,3',5,5'-tetramethylbenzidine(TMB)and hydrogen peroxide(H2O2)in weak acid solution.The absorption peak of OxTMB at 650 nm has a large spectral overlap with the fluorescence emission peak of TPPS at 664 nm,resulting in a decrease in the fluorescence intensity of TPPS.In the presence of mercury ions,the enzyme activity of AuNCs was inactivated;the catalytic ability of AuNCs was weakened.As a result,the produced amount of OxTMB decreased,weakening the inner filtration effect between OxTMB and TPPS and restoring the fluorescence of TPPS.Meanwhile,the fluorescence intensity of the gold nanoclusters was inhibited by mercury ions.Based on these facts,a ratiometric fluorometric method was constructed for mercury(?)ion.The linear response range of the method for mercury ion is 0.02-2.0 ?mol/L,and the detection limit is 11 nmol/L(3Sb/S).In summary,two ratiometric fluorometric methods were constructed for the determination of mercury(?)ion by using GSH-AuNCs and TPPS.They are simple,rapid,and sensitive and can be applied for determination of mercury ion content in the actual samples.This work provides an alternative method for the detection of mercury(?)ion in environmental water samples,food safety and cosmetics safety.