The Synthesis Of The Novel Fluorescent Carbon Quantum Dots And Their Applications

In recent years,carbon quantum dots(CDs)have attracted a lot of attention due to their excellent optical,chemical and biological properties.Compared with the other fluorescent nanomaterials,such as semiconductor quantum dots(QDs)with heavy metals as the essential composition to accomplish their high performance photoluminescent(PL),the biocompatibility of CDs is better,and the preparation of CDs is more convenient and green.In this paper,two kinds of CDs were successfully prepared via microwave treatment,and two kinds of CDs were characterized by various analytical methods.In addition,we studied the properties of two kinds of CDs.We obtained the following conclusions:(1)CDs were prepared by the one-step microwave treatment of denatured proteins(dBSA),which is a simple and green method for preparing high fluorescence CDs.In this system,the microwave irradiation method was taken,which saves a lot of time and energy,and suppressing undesired side-reactions.The quantum yield of denatured protein CDs(DPCDs)prepared by this method can reach 13.3%.At the same time,the DPCDs possess excellent up-conversion fluorescent properties.We have studied the formation mechanism of DPCDs,and the formation of DPCDs is proposed to proceed via four stages,including crosslinking,aromatization,nucleation,growth.In addition,the prepared DPCDs also exhibited the selectivity for Ag~+,which can be sensitive to Ag~+.When the range of Ag~+ concentration is from 0.1 to 10.0 ?M,a nice linear correlation exists between the quenching rate and the Ag~+ concentration,giving a calibration curve with R2 of 0.991.(2)CDs were prepared by green and convenient microwave treatment of ionic liquids(ILs,[PAVIm~+][Br-])and ethylenediamine mixtures.The IL-based CDs(ILCDs)exhibited a superior selective sensitivity for Cr(VI).When the concentration of Cr(VI)is in the range of 0.05-10.0 ?M,the linear relationship is shown between the fluorescence intensity of ILCDs and Cr(VI)concentration.The linear equation is:(F0-F)/F0=0.0222×CCr(?M)~+0.0047(R2=0.994).The detection limit is 0.015 ?M(S/N=3).The guideline value recommended by World Health Organization(WHO)is 50.0 ?g L-1(ca.1.0 ?M)in drinking water,which just lies in the detection range of our ILCDs-based Cr(VI)detection system.In addition,we also received satisfactory results by using the ILCDs for Cr(VI)detection in real samples.Moreover,the ILCDs can also be used as a fluorescent nanosensors to detect pH and temperature in the solution.