The Synthesis Of Functionalized Carbon Dots Based On Green Plant And Their Applications

Fluorescent nanomaterial with the advantages of nanomaterial and fluorescent material,including semiconductor quantum dots,rare earth element nanomaterial and metallic nanocluster,is significant to investigate.But materials above mentioned are high toxicity,requiring complicated process,high cost and not environment friendliness which limit the application.The carbon dots（CDs）have attracted tremendous attentions because of their low toxicity,environment friendliness and low cost.Up to now,so many carbon source and synthesis method have been developed.Moreover,the natural materials are more popular due to the low cost.But there are still some defects of CDs used natural materials as carbon source.For example,the quantum yields of CDs from natural materials are low and the surface groups are single,which result in the inferior sensitivity and selectivity.So the main assignment of us is preparing the functionalized CDs to enhance the fluorescence property.And heteroatom doping and surficial decoration are effective methods to obtain functionalized carbon dots.In the article,the natural materials and different passivation agents or co-reactant were employed to synthesize the functionalized CDs.And the CDs were applied in biology and detection area.In addition,the ratiometric fluorescence probe was fabricated used CDs we obtained and other fluorescent molecule,which broaden the application field of CDs.The following is the main research work:（1）The nitrogen atom doped CDs（N-CDs）were obtained from flowers of elm tree and ethanediamine by hydrothermal method.The N-CDs had the uniform diameter,high fluorescence intensity and stability.Moreover,the N-CDs were pH-sensitive and promising for bio-sensing.In addition,the N-CDs were also applied in Hela cells and mung bean sprouts imaging because of the low toxicity,which demonstrating the N-CDs had good biocompatibility and had significance in biology area.（2）The ratiometric fluorescence probe was formed used N-CDs above obtained and calcein.And the interaction of N-CDs and calcein was studied.With the adding of calcein,the fluorescence intensity of N-CDs was reduced,but the fluorescence intensity of calcein was increased.And there was an overlap between the emission of N-CDs and the absorbance of calcein.All of above proved that the resonance energy transfer occurred between N-CDs and calcein.In addition,the effect of pH on fluorescence properties of ratiometric fluorescence probe was researched.The optimal fluorescence spectrum was obtained at the p H of 6.So,the ratiometric fluorescence probe was prepared in the Britton-Robison buffer solution（pH=6）.Ultimately,the ratiometric fluorescence probe was employed simultaneously to detect the Cu ²⁺and Fe ²⁺.The detection limits were 0.50 and 0.31μM respectively.The method was simple which not required special apparatus and rigorous conditions.（3）The polyethylene glycol 8000 functionalized CDs（PEG-CDs）were synthesized by hydrothermal method used carrot plants and polyethylene glycol 8000（PEG）.The PEG-CDs were compared with the CDs which were prepared used carrot plants only in fluorescence intensity,quantum yield,lifetime,size distribution.The results indicated that all the properties above mentioned were improved.In addition,the PEG-CDs,with the good fluorescence stability and low toxicity,could stain the HeLa cells and mung bean sprouts and were used to cell and mung bean sprout imaging as fluorescence probe.（4）The CDs were prepared employing flowers of elm tree,ethanediamine and mercaptoacetic acid by hydro-thermal synthesis.The CDs had the high fluorescence intensity,high stability and broad size distribution.Moreover,the fluorescence could be quenched by Bi ³⁺.And there was a good linear relation between fluorescence intensity of CDs and the concentration of Bi ³⁺under the certain concentration.So,the CDs could be used to detect the concentration of Bi ³⁺.