| Rare-earth doped upconversion luminescent nanomaterials as a new type of nanoparticles has many excellent luminescence properties,such as no background interference,large anti-Stokes shift,high resistance to photo-bleaching,good tissue penetration depths and low biotoxicity,etc.Therefore,studying on rare-earth doped upconversion luminescent nanomaterials and their properties have attracted numerous researcher's interests.Based on this,firstly,we synthesized two kinds of Mn2+doped upconversion luminescent nanoparticles?UCLNPs?including Mn2+-NaYF4:Yb,Er UCLNPs and Mn2+-NaYF4:Yb,Tm UCLNPs,and then the surface of modification through a ligand exchange procedure.Lastly,we established redox reaction which realized the quick detection of uric acid?UA?,glucose?GO?,ascorbic acid?AA?,cysteine?Cys?and glutathione?GSH?.Detailed methods are listing as follows:?1?SynthesizedMn2+-dopedNaYF4:Yb,ErUCLNPsby hydrothermal and were modified with citrate.In the presence of the Fenton reagent,the hydroxyl radical was generated,and the Mn2+was oxidized,so that the luminescence intensity of UCLNPs could be quenched.And then,in biochemistry,some reactions can produce H2O2 as a byproduct in the presence of O2-dependent oxidases,such as glucose oxidase and uricase.When Fe2+existence,the Fenton reaction can produce hydroxyl radical,which leads to the fluorescence quenching of UCLNPs.Based on this,a sensing system for detecting UA and GO were designed in this chapter.And under optimal conditions,the fluorescence quenching signal showed good linearity with the H2O2 concentration in the range of 3.00×10-88 M6.00×10-55 M,and the detection limit of this assay was 1.30×10-88 M.Meanwhile,the linear concentration range for UA was 4.00×10-99 M1.00×10-55 M,and the lower limit of detection was 1.90×10-99 M.The linear concentration range for GO was 4.00×10-88 M8.00×10-55 M,and the lower limit of detection was 3.80×10-99 M.?2?The prepared Mn2+-doped NaYF4:Yb,Tm UCLNPs exhibited a emission in near infrared region and were modified by citrate.In the presence of the Fenton-like reagent,the hydroxyl radical was generated,so that the luminescence intensity of UCLNPs could be quenched.And then,in biochemistry,some reactions can produce H2O2 as a byproduct in the presence of O2-dependent oxidases,such as glucose oxidase and uricase.When Co2+existence,the Fenton-like reaction can produce hydroxyl radical,which leads to the fluorescence quenching of UCLNPs.And under optimal conditions,the linear concentration range and the lower limit of detection for H2O2 were 2.00×10-77 M1.00×10-55 M and 9.00×10-88 M.Meanwhile,the linear concentration range and the lower limit of detection for UA were1.00×10-66 M1.00×10-33 M and 4.00×10-77 M.The linear concentration range and the lower limit of detection for GO were 3.00×10-66 M3.00×10-44 M and 6.00×10-77 M.?3?In the study,the citrate modification of Mn2+-doped NaYF4:Yb,Er UCLNPs interacted with heavy metal ion(Fe3+)to leading the fluorescence quenching of UCLNPs.When the reducing agents were added in this system,the Fe3+was reduced and accompanied with UCLNPs fluorescence recovery.Based on this,we realized the detection of antioxidants such as AA,Cys and GSH.And the linear range of AA,Cys or GSH was 8.00×10-66 M to 2.00×10-44 M,2.00×10-66 M to 1.80×10-44 M,8.00×10-77 M to 1.50×10-44 M respectively.The limit of detections were3.55×10-66 M,1.22×10-66 M,2.30×10-77 M respectively. |
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