The Preparation Of Novel Doped Carbon Quantum Dots And Their Application In Fluorescent Detection

Carbon quantum dots(CDs),as one of fluorescent nanoparticles,have attracted tremendous attention with many outstanding features such as,excellent photostability,biocompatibility,low toxicity,easy modification,abundant raw materials.And has been widely applied in chemical sensing,biological applications catalysis and optoelectronic devices.However,the emission wavelengths of the reported carbon quantum dots are mostly in the blue or green light region.Therefore,the optical properties adjusting of CDs and synthesis of CDs with long wavelength hold more great importance.In this dissertation,based on the easy modification of CDs,we have preparated novel carbon quantum dots with different doping elements,and then they were applied to detect methyl parathion,copper ion and lysine.The research contents are as follows:1.Solid-phase synthesis of Sc doped carbon dots for rapid fluorescent sensing of Cu2+In this work,Sc doped carbon dots(Sc-oCDs)were synthesized by a facile solid-phase synthetic strategy.And the the optimum synthesis conditions(reaction temperature,time and the mass ratio of Sc2O3 and o PD)of CDs were explored.Moreover,the morphology and properties of Sc-o CDs was characterized by TEM,UV-adsorption spectra,fluorescence(FL)spectra etc.In addition,the fluorescence of Sc-o CDs could be quenched by copper ions through dynamic quenching effect(DQE).Therefore,Sc-o CDs were successfully employed for determining Cu2+ in water samples.2.Dual emission carbon dots for specific ratiometric detection of lysine and p H at different wavelengthIn this context,dual emission carbon dots(r DCDs)were prepared by hydrothermal method.And the morphology and optical properties of this nanoparticle were characterized by TEM,FIRT,XPS,UV absorption spectra etc.r DCDs showed two fluorescence emission peaks located at 440 nm and 624 nm when excitated at 380 nm.Lysine can make the emission intensity at 440 nm increased while the red fluorescence intensity remained unchanged.,Moreover,we also found that the fluorescence intensity of r DCDs at 624 nm gradually decreasedwith the p H value increased in the range of 1.5-5.0,while the blue fluorescence intensity remain unchanged at the same time.In view of the above phenomenon,we constructed a ratiometric fluorescent probe for specific detection of lysine and intracellular p H based on the different wavelength of r DCDs,and successfully realized the determination of lysine in human serum.3.The detection of parathion-methyl pesticide residues based on carbon dots and methyl parathion hydrolaseIn this paper,we propose a new method for detecting parathion methyl,based on the fluorescence intensity of NCDs could be quenched by p-nitrophenol which is the hydrolysis product of PM catalyzed by methyl parathion hydrolase.And the quenching mechanism is inner filter effect(IEF)and molecular interactions between NCDs and p-nitrophenol.In addition,we have optimizated the detection conditions of PM,and the linear range and detection limit of PM by this method were also investigated.Finally,it was successfully used to detect PM in water,soil and pear.