Preparation And Properties Of Functional Carbon Quantum Dots

Carbon Quantum Dots(CQDs)are quasi-spherical carbon nanoparticles with a diameter of less than 10 nm.which are mainly divided into graphene quantum dots,carbon nanodots and polymer quantum dots.In the structure of carbon atoms to Sp2/Sp3 hybrid into the bond,the surface contains a large number of oxygen-containing functional groups and polymer molecules,so the surface of carbon quantum dots can be modified to make it multi-functional.Compared with organic dyes and conventional semiconductor quantum dots,carbon quantum dots have many advantages,such as strong fluorescence emission in the visible spectrum,excellent water solubility,low toxicity,good anti-bleaching,easy synthesis,surface modification and so on.As a result,carbon nanotubes have become new nanomaterials for biosensing,biomimetic,and drug delivery potential applications.At present,under the continuous efforts of domestic and foreign scholars,the application area of carbon quantum dots is gradually expanded.However,there are still some limitations in the preparation of multifunctional carbon quantum dots.The application of carbon quantum dots is too simple to extend its application in other fields.In the process of preparation,the introduction of functional inorganic matter,which increases the biological toxicity of quantum dots.Therefore,the preparation of a multi-functional carbon quantum dots has attracted more and more scholars attention.The basic structural elements of the organism,such as amino acids,nucleotides and other skeletons are composed of carbon elements,so the composition of the most basic elements of life is carbon.Meanwhile,pure carbon material is usually non-toxic,low toxicity and biocompatible to the living body.Adenosine triphosphate(ATP)is composed of adenine,nuclein and three phosphate groups.In the time of the ATP hydrolysis,much energy can be released which is the immediate source of energy in the body.ATP is rich in carbon sources,nitrogen sources and phosphorus sources,and it can be used as carbon materials for the preparation of carbon quantum dots.In this paper,N,P co-doped carbon quantum dots(N-P-CQDs)were synthesized by one-step hydrothermal method,which use ATP as a carbon source with good biocompatibility and realized the application of cell multi-color imaging.In order to further expand the function of carbon quantum dots,ATP was combined with biocompatible graphene and rare earth lanthanum elements with antibacterial properties.The carbon quantum dots and the antimicrobial properties were synthesized by one step hydrothermal method.Finally,the two types of carbon quantum dots prepared were conventionally characterized,such as their composition,physical properties and biocompatibility.In addition,the antibacterial properties of the carbon quantum dots were evaluated.The specific research contents are as follows:1.In this paper,ATP as a carbon source with good biocompatibility and containing N and P element was prepared by one-step hydrothermal method.And the prepared carbon quantum dots with good water-solubility and the dependency of ecitation wavelength(N-P-CQDs).The morphologies,structural properties and fluorescence characteristics of N-P-CQDs were characterized by TEM,XRD,FTIR,PL,UV,XPS and EDS.The results show that N-P-CQDs are homogeneous and have no obvious agglomeration.The particle size distribution is broad,mainly distributed in the range of 2.6-4.8 nm.The fluorescence quantum yield of N-P-CQDs is 9.8%,and its fluorescence has obvious excitation wavelength dependence and luminous stability and no photobleaching.N-P-CQDs were irradiated under Xenon lamp or added to a solution contained different ions and found that the fluorescence intensity was almost unchanged.The cells cytotoxicity and hemolysis experiment show that N-P-CQDs have good biocompatibility.In the process of co-culture with human cervical cancer cells(HeLa),laser confocal microscopy can be used to clearly show that in different wavelengths of light source,HeLa cells show blue,green and red multi-color fluorescence.Finally,in vivo toxicity experiments showed that N-P-CQDs had no significant toxic effects on mouse body weight and various organs.Thus,in future cell imaging applications,cell monitoring can be achieved by adjusting the excitation wavelength.2.In order to further explore the application of prepared carbon quantum dots in the field of antibacterial nano-additives,we disulfide disodium triphosphate(ATP)and lanthanum chloride,and then prepared by a step hydrothermal method with a narrow particle size distribution and strong fluorescence properties of lanthanum-doped carbon quantum dots(La-CQDs),expanding the carbon quantum dots in the anti-bacterial function,through UV,PL,FTIR,EDS,XRD,XPS and TEM and other modern means of analysis of lanthanum doped ccarbon quantum dots,physical properties and fluorescence characteristics of the conventional characterization.The results show that the carbon quantum dots have good water solubility,light stability and biocompatibility.La-CQDs can also be applied to cell imaging.La-CQDs show different colors of fluorescence inside lung cancer cells(A549)under the excitation of different wavelengths.Cell MTT assay and hemolysis rate experiment showed that La-CQDs had good biocompatibility.Meanwhile,in vivo toxicity experiments showed that La-CQDs had no significant toxic effects on mouse body weight and various organs.The results of bacterial MTT assay and minimum bacteriostatic concentration showed that the antibacterial ability of La-CQDs was greatly enhanced compared with N-P-CQDs.3.On the basis of this,we prepared La-CQDs@PVA fluorescent composite films by dissolving La-CQDs powder in deionized water and PVA by solution blending.La-CQDs@PVA fluorescent composite films were characterized by PL,TGA and SCA.Hydrophilicity,fluorescence properties and cytotoxicity of the composite films were evaluated.The release of La-CQDs in the PBS solution was obtained by in vitro release experiments.The antibacterial properties of the La-CQDs@PVA fluorescent composite films were studied by bacterial adhesion experiments.Finally,it is proved that the La-CQDs@PVA fluorescent composite film through the wound healing experiment,promoting the healing of the wound and prevent the wound infection.