The Synthesis Of Dual-doped Fluorescence Carbon Dots And Its Application In The Detection Of Small Molecules

Carbon Dots(CDs)are a new type of fluorescent Carbon nanomaterials with a size less than 10 nm.They are prepared by“top-down”cutting by physical/chemical methods and“bottom-up”carrying out the dehydration and carbonization processes(including hydrothermal,microwave,combustion concentrated acid etc.).Because of its unique optical properties,low toxicity,excellent water solubility,facile preparation and modification,carbon dots have potential application in sensing,therapy,biological imaging,optoelectronic devices.However,the weak fluorescence intensity and low quantum yield of"naked"carbon dots,which emission blue or green fluorescence,makes the carbon dots vulnerable to background interference in specific applications.It is of great significance to prepare carbon dots with high quantum yield and long wavelength fluorescence emission.The main summary is as follows:(1)Hydrothermal synthesis of orange-emitting nitrogen and fluorine co-doped carbon dots(N,F-CDs)for the determination of 2,4,6-trinitrophenol.N,F-CDs were synthesized by one-step hydrothermal method from 4-fluoro-phenylenediamine and dopamine.The carbon spot has two emiison peaks located at 370 nm and 570 nm.The relative quantum yield of N,F-CDs was calculated(18.6%)by using rhodamine B as reference.Absorption spectrum of TNP significantly overlaps with the excitation spectrum of orange-emission N,F-CDs,which results in efficient inner-filter effect and the fluorescence quenching of N,F-CDs by TNP.Based on this we established fluorescent probe for the detection of TNP.The linear range and detection limits of TNP are13.3-50μM,and 37 nm,respectively.At the same time,the method was applied to the determination of TNP in actual sample detection.(2)Dual-emission ratio fluorescence detection of curcumin and hypochlorite(Cl O~-).The ratio fluorescence probe was established by the Purple fluorescence of N,F-CDs and the yellow fluorescence of curcumin.At the same time,the phenols and methoxy groups of curcumin can be reduced to quinones by hypochlorite(Cl O~-).Based on this,curcumin and hypochlorite was sequentially detected.The linear range of curcumin and hypochlorite are1.3-30μM/30-63μM and 0.24-13μM,respectively.The detection limit of curcumin and hypochlorite are 0.2μM and25 n M,respectively.The method in detecting hypochlorite was also verified in milk samples.(3)Red-emitting N,Br co-doped carbon dots as“turn off-on”fluorescent probe for sequential detection of Ag~+and biothiols.Nitrogen-bromide co-doped carbon dots(N,Br-CDs)were synthesized by one-step hydrothermal method from 4-bromo-o-phenylenediamine and dopamine.The N,Br-CDs exhibits the characteristic emission located at 640 nm at a single excitation wavelength of 570 nm and the quantum yield of N,Br-CDs 24.6%.Due to the fluorescence of carbon dots could be quenched by Ag~+and recovered by biothiols.Based on this,we established“turn off-on”fluorescent probe for sequential detection of Ag~+and biothiols.The linear range and detection limit of Ag~+was 0.167-13.3μM and 42 n M,respectively.The linear ranges of biothiols(GSH,Hcy and Cys)were 0.3-0.75μM,0.5-11.7μM and 0.3-5.8μM,respectively.The detection limits were 22 n M,15 n M and 33 n M,respectively.The reliability of this method was verified in human urine samples.