Preparation Of Three Fluorescent Carbon Dots And Their Application In Drug Analysis

Carbon dots（CDs）is a nearly spherical zero-dimensional carbon nanomaterial.Due to its excellent photoluminescence properties,light stability,small size,good biocompatibility,low cytotoxicity or non-toxic,etc.It widely used in the fields of chemical analysis,biological analysis,drug analysis,drug delivery,solar devices,biological imaging,and cancer diagnosis,etc.In this paper,three kinds of fluorescent CDs with different properties were successfully prepared by using p-phenylenediamine and different acids as carbon sources,through the solvent thermal method and microwave method of regulation and optimization of conditions.They will be applied to the detection of chlortetracycline,doxycycline and gatifloxacin.The contents were summarized as follows:（1）An orange fluorescent CDs was synthesized from p-phenylenediamine and acetic acid.FTIR characterization shows that there are a large number of carbon and oxygen-containing functional groups on the surface of the fluorescent CDs,which has excellent hydrophilicity.Under 527 nm excitation,the CDs has the best emission peak at 576nm,and has a special excitation dependence.A new method for detection of chlortetracycline based on aggregation induced fluorescence enhancement.The fluorescence intensity of CDs increased significantly with the increase of CTC concentration.The linear range for CTC determination was found to be the range from 1.0×10^-8mol/L to 5.0×10^-6mol/L,and the detection limit was 3.30 nmol/L.Therefore,we have established a dual-function probe sensor for chlortetracycline.（2）The double-emitting fluorescent CDs were synthesized using citric acid and p-phenylenediamine as carbon sources and their application to doxycycline.The emission peaks of the CDs were 459 nm and 583 nm at the excitation wavelength of 361 nm.Based on static quenching,CDs and doxycycline were synthesized a non-luminescent ground state complex,which can be used to detect doxycycline.The fluorescence quenching degree of CDs increased significantly with the increase of doxycycline.Studies show that within the concentration range of doxycycline from 1.0×10^-8to 5.0×10^-5mol/L,there was a good linear relationship between the fluorescence quenching degree((ΔI_F=(I_F0-I_F))of CDs and doxycycline,and the detection limit was 5.10 nmol/L.Based on this,doxycycline tablets were successfully detected in actual samples.（3）The Red-fluorescent CDs were synthesized using p-phenylenediamine and sulfuric acid as carbon sources and its application to gatifloxacin was studied.The excitation and emission peaks of the synthesized CDs are 599 nm and 687 nm,respectively.Based on charge transfer mechanism,the degree of fluorescence quenching of CDs was directly proportional to the concentration of gatifloxacin.When the concentration range of gatifloxacin was 0.01 to 40μmol/L,it had a good linear relationship with the fluorescence quenching degree of CDs,and the detection limit was 2.14 nmol/L.Based on this linear relationship,the method was successfully used to detect the content of gatifloxacin in actual samples.