Preparation And Biological Imaging Study Of Caffeic Acid Derived Yellow And Green Fluorescent Carbon Nanodots

Fluorescent carbon nanodots are a new class of carbon nanomaterials,due to carbon nanodots has excellent water solubility,chemical inertness,biocompatibility,easy light bleaching,easy surface functional and simple preparation,and many other advantages,and it has attracted more and more people's attention,in the biological imaging,sensing,biomedicine,photocatalysis,optoelectronic devices have demonstrated the potential application value.Although there have been many reports on carbon nanodots,most of them show strong emission in the blue area,the emission in the longer wavelength region(yellow to red)is weak.Because of the blue autofluorescence of biological matrix and photodamage of biological tissues by the ultraviolet excitation light,the further application of carbon nanodots is limited.Therefore,it is necessary to prepare carbon nanodots which can show emission in a longer wavelength region.The fluorescence properties of carbon nanodotos can be regulated by the heteroatom doping(such as quantum yield and long wavelength emission).The main contents of this paper are caffeic acid as carbon precursor,and by doping different heteroatoms to regulate the fluorescence properties of carbon nanodots.At the same time,the preparation conditions of the experiment were optimized.Finally,the yellow and green fluorescent carbon dots were prepared with caffeic acid and ethylenediamine as the raw material,and they can be applied to biological imagingsuccessfully.The main research works: 1.Carbon nanotots were prepared by caffeic acid and the sources of different heteroatom,the sources of different heteroatom were formamide,ethylenediamine,cysteine hydrochloride,urea etc.Among of carbon nanodots,some carbon nanodotshave a lower quantum yield,which were prepared by caffeic acid with cysteine hydrochloride,urea and formamide.However,the carbon nanodots were prepared with caffeic acid and ethylenediamine,which exhibited higher quantum yields.2.By adjusting the molar mass ratio of caffeic acid and ethylenediamine,the carbon nanodots prepared showed blue fluorescence by molar mass ratios of 10:1,5:1,2:1and the carbon nanodots showed yellow fluorescence when the molar mass ratio was 1:1,the carbonnanodots showed green fluorescence by molar mass ratios of 1: 2,1: 5,1: 10 etc.3.By optimizing conditions,the yellow and green fluorescent carbon nanodots were prepared with high quantum yield,which of reaction conditions were the molar ratio of caffeic acid and ethylenediamine was 1:80 and 1:1,the reaction temperature was 200?.They exhibited lower cytotoxicity,higher light stability,and were successfully applied to cell imaging.