Study On The Design,Property And Analysis Application Of The Original Graphene Quantum Dots

Graphene quantum dots are kinds of carbon nanomaterials that have graphene sheets structure and the character of shine like quantum dots.Graphene quantum dots have the advantages of low toxicity,environmental protection,stable photoluminescence,high fluorescence quantum yield and good biocompatibility.Because of these advantages,graphene quantum dots are used in different fields such as photoelectric sensors,biological imaging,photoelectrocatalysis and medical diagnosis.However,at present,graphene quantum dots still have the disadvantages including complicated synthesis methods,strong hydrophilicity,lack of hydrophobicity,low fluorescence quantum yield and single performance,which greatly limit their applications.Therefore,it is particularly significant to develop a simple and easy-to-function method for synthesizing graphene quantum dots and achieve high fluorescence intensity.In this paper,new type of graphene quantum dots were designed which synthesized by hydrothermal method and dry burning method.The method can explore structure and improve properties.The applications of graphene quantum dots in analytical detection,cell imaging,preparation of new materials and medical applications are develped.D-penicillamine functionalized graphene quantum dots are synthesized by introducing D-penicillamine on the surface of graphene quantum dots.D-penicillamine functionalized graphene quantum dots have strong fluorescence intensity and strong coordination with Fe³⁺that can be designed as fluorescence sensor for the determination of Fe³⁺.D-penicillamine functionalized graphene quantum dots are prepared by one-step hydrothermal method of citric acid.The fluorescent quantum yield of D-penicillamine functionalized graphene quantum dots reaches 99.8%,which is much better than that of the reported graphene quantum dots.nder strong acidic conditions,the peak fluorescence intensity linearly decreases with increasing concentration of Fe³⁺in the range of 0.004¹.8 m M with the detection limit of 1.2×10^-6 M?S/N=3?.The D-penicillamine functionalized graphene quantum dots as a novel fluorescent probe also possesses excellent selectivity for the optical detection of Fe³⁺.All metal and nonmetallic ions and amino acids,especially Fe²⁺,don't interfere with the fluorescent detection of Fe³⁺.It has been successfully applied in the detection of Fe³⁺in iron supplement oral liquids.Based on the introduction of folic acid on the surface of graphene quantum dots,the folic-functionalized graphene quantum dots have strong and tunable fluorescence emission under visible light excitation.By controlling the ratio of raw materials,different graphene quantum dots can be prepared according to different requirements.By controlling the temperature,the introduction of folic acid molecule not only maintains its special structure,but also enhances the fluorescence intensity.Due to the specificity of folic acid structure,folic-functionalized graphene quantum dots have a specific recognition effect on cancer cells and can be used for cell imaging.So folic-functionalized graphene quantum dots can be used for cell imaging to detect cancer cells.It was confirmed that folic functionalized graphene quantum dots have specific recognition effects on HepG2 cancer cells through fluorescence microscopy.Due to the specificity of folic-functionalized graphene quantum dots and its strong coordination with Hg²⁺,it can be designed as a fluorescence sensor for the determination of Hg²⁺.Under strong acidic conditions,with the increase of Hg²⁺concentration,the fluorescence intensity of folic-functionalized graphene quantum dots decreased linearly in the range of 2.0×10^-65.0×10^-1212 M,and the detection limit was 1.7×10^-1212 M?S/N=3?.All of the metal and nonmetal ions tested did not interfere with the optical detection of Hg²⁺.The sensitivity and selectivity of Hg²⁺are much better than reported optical sensors.This method has been successfully applied to the determination of Hg²⁺in water samples.Dodecylamine-functionalized graphene quantum dots are synthesized by introducing dodecylamine with a hydrophobic alkyl chain on the surface of graphene quantum dots.Dodecylamine-functionalized graphene quantum dots have excellent amphiphilicity that can be designed as a template for synthesizing other multi-functional materials which open up new areas of graphene quantum dots.Dodecylamine-functionalized graphene quantum dots consist of small graphene sheets with abundant amino,carboxyl,acylamino,hydroxyl and alkyl chains on the edge.The amphiphilic structure gives the dodecylamine-functionalized graphene quantum dots high surface activity.Dodecylamine-functionalized graphene quantum dots can reduce the surface tension of water to 30.8 mN·m^-1 and the interfacial tension of paraffin oil/water to 0.0182 mN·m^-1.The surface activity is much better than that of previously reported solid particle surfactants for Pickering emulsions and is close to that of sodium dodecylbenzenesulfonate,which is a classical organic surfactants.Dodecylamine-functionalized graphene quantum dots are employed as solid particle surfactants for stabilizing styrene-in-water emulsions.The emulsions exhibit excellent stability at pH=7.0.However,stability is lost when the pH is more than 9.0 or less than 4.0.Therefore,the dodecylamine functionalized graphene quantum dots can be designed as pH-switchable which achieved application in other fields.A stable styrene-oil-in-water Pickering emulsion is used as a template and 2,2?-azobis?2-methylpropionitrile?as initiator to trigger emulsion polymerization.The as-prepared polystyrene nanospheres display a uniform morphology with a narrow diameter distribution of204 nm.Different particle sizes of polystyrene nanospheres can be prepared by changing the concentration of graphene quantum dots.The method is not only simple,but also the polystyrene nanospheres have a small and controllable particle size.The polystyrene nanospheres have fluorescent because of the fluorescent dodecylamine-functionalized graphene quantum dots coated the surfaces.The specific groups of dodecylamine-functionalized graphene quantum dots on the surface of polystyrene nanospheres were used to coordinate with metal ions such as Pb²⁺,Ni²⁺,Cu²⁺,and Cd²⁺,the adsorption behavior was studied.The result shows that pH has a significant effect on the adsorption of polystyrene nanospheres.Pb²⁺Adsorption effect of Pb²⁺is the best and the best pH value of 8.0.It is considered that polystyrene nanospheres are feasible,recyclable and environment-friendly for Pb²⁺adsorption and applied to adsorpt the Pb²⁺in electroplating wastewater.