Experimental Study Of The Development Of Analytical Methods For The Detection Of Glucose And Iron Ion

Two ways of the signal modulation by the sensing of target materials can be established,one is signal reduction and the other is signal enhancement.In this paper,according to the requirement of fast detection of the object,UV-visible absorption spectra and fluorescence spectra were applied to fabricate several methods to realize the detection of some specific targets through color or fluorescence spectrometry.Three sections of this paper were developed as follows:Chapter 1 Fabrication of signal-off assay based on MnO2 nanosheets for the visual detection of glucoseIn this chapter,a visual assay for the change of hydrogen peroxide concentration is established according to the fact that yellow MnO2 can be converted into colorless Mn2+ based on the redox reaction of MnO2 with hydrogen peroxide.Then,the visual method can be further developed to test glucose in two steps based on the reaction between MnO2 and H2O2.The first step was the formation of H2O2 due to the catalysis of glucose by Glucose Oxidase(GOD),then the change of color the introduction of uniform dispersion of yellow MnO2 nanosheets can be applied to quantify the concentrations of glucose.Chapter 2 Detection of Fe3+ through signal-off fluorescence assay based on graphene quantum dotsIn this chapter,nitrogen and sulphur co-doped graphene quantum dots(N-S/GQDs)was synthesized through pyrolysis of mixture of citric acid and GSH.As-prepared NS/GQDs owned strong blue fluorescence.Fluorescence intensity of N-S/GQDs can be quenched due to the specific interaction of N-S/GQDs and Fe3+,and then the decreased intensities of N-S/GQDs can indicate the concentration of Fe3+.In the actual complex system,N-S/GQDs can detect Fe3+ accurately in serum environment.In addition,cell imaging can be modulated through the introduction of N-S/GQDs in the presence or absence of Fe3+.Chapter 3 In situ growth of plasmonic gold nanoparticles for the signal-on colormetric assay of glucoseIn situ formation of Gold nanoparticles(Au NPs)showed different color due to the surface plasmon resonance(SPR)effect.Thus,signal-on colorimetric assay for the highly sensitive and selective detection of glucose has been conducted.The formation of H2O2 was happened due to the catalysis of GOD to glucose.And then,under the stability effect of trace amounts of tween-20,the reaction between AuCl4-and H2O2 performed to formation of gold nanoparticles to imply the concentration of glucose.Thus,this change could be observed with the naked eye or a UV-vis spectrophotometer.Some common interfering compounds in beverages,including other sugars and food additives,did not affect glucose sensing.The proposed Au NP-based colorimetric assay could be successfully used to determine glucose in several beverages,with the consistent results with the standard method.