Fabrication Of Functionalized Graphene Modified Electrode And Their Applications In The Pharmaceutical Analysis

As a novel two-dimensional single-atom-thick carbon material,graphene?GR?has unique advantages in the construction of chemically modified electrode.However,GR nanosheets are hydrophobic and trend to agglomerate irreversibly by ?-? stacking interaction and Van der waals,which hinders its further application as electrode modified materials.In order to overcome this problem,the functionalization of GR has been applied.Functional reagent not only improves GR nanosheets dispersibility,but also allows them to be further decorated with other nanomaterials,such as nanometal particles,which possess fast electron transfer rate,high catalytic efficiency and so on.Based on this,three kinds of voltammetric sensors were fabricated with excellent performance for pharmaceutical analysis.The main research is expressed as follows:?1?A simple,environmental-friendly and cost-effective approach for preparation of polyethyleneimine-functionalized graphene?PEI-GR?was proposed for constructing a voltammetric sensor platform.The prepared composite was characterized by several techniques;including Transmission electron microscope?TEM?,UV-vis spectrum?UV-vis?and Fourier transform infrared spectroscopy?FT-IR?.This voltammetric sensor showed strong accumulation ability and excellent voltammetric response for puerarin.The electrochemical behavior of puerarin was investigated systematically.Under the optimized conditions,a lower detection limit of8.0×10^-8 mol L^-1?S/N=3?and a wide linear detection range from 3.0×10^-7 to 1.0×10^-5mol L^-1were achieved by the linear sweep voltammetry?LSV?.Additionally,this effective method was proved to be suitable for the determination of puerarin in Puerarin Injection with satisfactory results.?2?A novel and sensitive electrochemical sensor for rutin determination was developed based on cetyltrimethylammonium chloride?CTAC?functionalized graphene?Gr?and palladium nanoparticles?Pd?composite?CTAC-Gr-PdNPs?.Rutin displayed remarkably increased electrochemical activity on CTAC-Gr-PdNPscomposite modified electrode due to the synergistic effect of the large surface area and electrocatalytic activity of both Gr and Pd nanoparticles,which offers the feasibility for highly sensitive determination of rutin.The electrochemical properties of rutin on the modified electrode were investigated by cyclic voltammetry?CV?and square wave voltammetry?SWV?.Under the optimum experimental conditions,the oxidation peak current of rutin was proportional to its concentration in the range of2.0×10^-8-1.0×10^-6 mol L^-1 and the limit of detection?LOD?was of 8.0×10^-9 mol L^-1?S/N=3?.The developed method was successfully applied to determine rutin in real sample with satisfactory recoveries,showing that fabricated sensor has potential in application.?3?This part reported a one-pot synthesis of Co nanoparticles doped amino-graphene nanocomposites?Co-amino-Gr?,involving in situ generation of Co nanoparticles?NPs?.The simultaneous reduction of graphene oxide?GO?and Co2+ to produce Co-amino-Gr had been achieved under mild reaction conditions using an environmentally benign reducing agent,glycine.By combining the merits of amino-Gr and the Co NPs,a highly sensitive electrochemical sensor was erected and used to detect baicalin based on the Co-amino-Gr nanocomposites.Under optimum conditions,the response peak currents were linear related with baicalin concentrations in the range of 1.0×10^-8-8.0×10^-7 mol L^-1 with a lower detection limit of 5.0×10^-9mol L^-1?S/N=3?.Additionally,the proposed method was used to detect baicalin in the medicinal capsules with satisfactory results.