Preparation,Properties And Application Of Heteroatom-Doped Carbon Dots

Carbon dots have become the most popular nanomaterials among the nanocarbon family,including fullerene,carbon nanotube and graphene,since they were found in 2004.Carbon dots possess the excellent optical performance,the great chemical stability,the good biocompatibility and the adjustable surface function.They have been widely researched in the field of bioimaging,environmental testing and nanomaterials with enormous application potential.Heteroatom-doping is often used for improving the properties of carbon materials such as carbon nanotube and graphene.Therefore,heteroatom-doped carbon dots have caught many researchers' eyes and developed very well.The doped heteroatom can tune the properties of carbon dots,including the electrical character and the chemical features inside and outside carbon dots.Nitrogen,sulfur,phosphorus and boron are usually doped in carbon dots singly or together to change their properties.In this paper,the biomolecules containing heteroatom are employed to synthesize the many kinds of heteroatoms co-doped carbon dots with the hydrothermal method.Nitrogen and sulfur co-doped carbon dots and nitrogen,phosphorus and sulfur co-doped carbon dots are fabricated from heparin sodium and thiamine pyrophosphate,respectively.The prepared carbon dots have been successfully applied in cell imaging,ion detection and pH response.Some novel results are obtained in this paper as following:1.Preparation,properties and application of nitrogen and sulfur co-doped carbon dotsHeparin sodium is used to fabricate carbon dots as the precursor,which will liberate D-glucosamine,D-glucuronic acid,L-iduronic acid,acetic acid and sulphuric acid after complete hydrolysis.Under a hydrothermal condition,heparin sodium can directly form the functionalized nitrogen and sulfur co-doped carbon dots without any other additional or subsequent chemicals.The as-prepared carbon dots possess obvious graphite structure and high crystallinity.The existing pyrrole and thiophene rings in the carbon dots due to the doped nitrogen and sulfur atoms make more surface defects to enhance the fluorescence quantum yield.The obtained carbon dots have been successfully employed in the cell imaging thanks to their low toxicity.What's more,Fe3+ will induce the fluorescence quenching of the prepared carbon dots,so they can be used as the fluorescence probe for the selective detection of Fe3+.2.Preparation,properties and application of nitrogen,phosphorus and sulfur co-doped carbon dotsThiamine pyrophosphate is used to synthesize carbon dots with the hydrothermal method.The existing pyridine rings,thiazole rings,amino groups and pyrophosphoric groups in the thiamine pyrophosphate molecules will be recombined or preserved after hydrothermal treatment and then the nitrogen,phosphorus and sulfur atoms can get into the generated carbon dots.The prepared carbon dots own lots of defects,which will improve the fluorescence quantum yield of the carbon dots.The quantum yield is 19.6%which is obviously higher than that of many other reported carbon dots.The obtained carbon dots can be applied in pH quantitative detection for basic solutions because of the linear relationship between fluorescence intensity and pH in the alkaline range.