The Preparation And Application Of Nanoprobes For Visual Detection

The surface effect,small size effect,macroscopic quantum tunneling effect,quantum size effect and dielectric confinement effect of nanomaterials endow them with properties of light,magnetism,electricity,heat and mechanics,which are extensively used in catalysis,sensing,food and biomedicine.In recent years,nanoprobes used for visual detection have attracted much attention on account of its rapid,convenient and sensitive detection advantages.As three dimensional graphene has large specific surface area,metal or metal oxide supported on three dimensional graphene with enzymatic catalytic properties can effectively promote electron transfer,providing more active sites to enhance the catalytic properties.These enzyme-like nanomaterials could realize visual detection.However,noble metals are always doped in the enzyme-like catalytic materials in order to obtain better catalytic effect,leading to high cost.Carbon dots could achieve visible detection under UV light and have been widely used in biosensing and imaging due to its excellent ability of good optical and chemical stability,low toxicity and simple preparation.However,there are still some problems about carbon dots,such as the emission wavelength of fluorescence carbon dots and the detection mode are single.Based on that,the following create works have been developed:1.Three dimensional reduced graphene oxide nickel ferrite/nickel oxide nanoparticles?3DRGO-NiFe₂O₄/NiO NPs?for visual detection of H₂O₂ and organophosphorus pesticides.In this work,a low-cost mimetic peroxidase three dimensional reduced graphene nickel ferrite/nickel oxide nanoparticles?3DRGO-NiFe₂O₄/NiO NPs?were prepared by one-pot hydrothermal method.The 3DRGO-NiFe₂O₄/NiO NPs could be used to catalyze the decomposition of hydrogen peroxide?H₂O₂?to hydroxyl radical?·OH?and oxidation of substrates3,3',5,5'-tetramethylbenzidine?TMB?to a blue color which could realize the response of H₂O₂with detection limit?LOD?as low as 0.1?M.H₂O₂ could be produced by acetylcholinesterase?AChE?,choline oxidase?ChOx?and acetylcholine chloride?AChCl?,while the enzyme activity of AChE could be inhibited by organophosphorus pesticide?OPs?.Based on the catalytic properties of 3DRGO-NiFe₂O₄/NiO NPs and above enzyme inhibition reaction,a method for detection OPs was established.Dicholorvos?DDVP?was chosen as a model of OPs and test paper was designed to combine with smart phones APP named Colorgrab to fast and sensitively detect residue of DDVP on the surface of fruit and vegetables.2.The ratiometric carbon dots?RIM-CDs?were used for visual detection of ClO^-under UV light and the application of cell imaging.In this work,a ratiometric carbon dots?RIM-CDs?were synthesized by one-pot hydrothermal method,which exhibited two emission peaks at 426 nm and 541 nm.The fluorescence intensity was decreased at 426 nm while increased at 541 nm after addition of ClO^-.The viaration of fluorescence color for the responding solution coule be observed under UV light.Detection for ClO^-based on RIM-CDs possessed good selectivity and the LOD for ClO^-was calculated to be0.93?M?linear range of 2.5-55?M?.Serum and rat brain microdialysates were selected as real samples for determination of ClO^-and the result of recovery was good.Furthermore,the RIM-CDs were applied in cell imaging.3.Fluorescence and colorimetric dual mode carbon dots were used for endogenous and exogenous ClO^-imaging.In this work,RD-CDs were prepared to detect of ClO^-by fluorescence and colorimetric dual mode.The LOD for ClO^-by fluorescence mode was calculated to be 0.083?M?linear range of0.1-100?M?and 2.2?M?linear range of 5-200?M?by colorimetric mode.Compared with RIM-CDs prepared in above work,the detection sensitivity based on RD-CDs toward ClO^-was improved and it realized dual mode detection.Both fluorescence and colorimetric modes could be used for quantification of ClO^-in serum and rat brain microdialysates samples.Hela cells and RAW264.7 cells were selected for endogenous and exogenous imaging of ClO^-.