Application Of Enhanced Dual-wavelength Light-emitting Diode-induced Fluorescent Capillary Electrophoresis In Analysis And Detection

As an effective separation and analysis technology,capillary electrophoresis(CE)is widely used in the fields of environment,biology,medicine and food because of its high separation efficiency,fast analysis speed,low reagent consumption and many separation modes.However,the problems of low injection volume and short optical path limit the sensitivity of CE coupled with the spectral detector.Although CE combined with the commercial laser induced fluorescence detector(LIF)and mass spectrometry detector(CE-MS)can greatly reduce the detection limit of CE,the high cost of these detection techniques make them unpopular in most of the routine laboratories.In addition,with the increase of sample complexity,multi-throughput detection has become a development trend.However,due to the difference in excitation wavelength,it is currently rare to perform simultaneous detection of multiple types of targets in the same sample.The CE system constructed using light-emitting diodes(LEDs)as excitation light sources can meet the requirements of low cost and multi-wavelength detection,and its small size also meets the requirements of miniaturized laboratories.Therefore,it is very valuable for improving detection sensitivity and detection throughput to build a CE detection system that uses LEDs as the excitation light source.In this work,an enhanced LEDIF-CE detection system was designed and self-assembled,and a dual-wavelength LEDIF-CE enhanced detection system was built on this basis.The detection performance of the two methods was verified by respectively or simultaneously detecting amino acids and peptides.Here,the developed dual-wavelength LEDIF-CE enhanced detection system was further applied to the analysis of fluorescent carbon dots to monitor its performance and scope of application.Carry out research work from the following aspects:This work self-assembled enhanced LEDIF capillary electrophoresis instrument to improve the sensitivity of the LEDIF detection system.By comprehensively considering the outer diameter and inner diameter of the capillary tube,the thickness and height of the detection plate,and the optimal reflectivity of the coating material,a silver-plated concave silver mirror was designed and customized.A simple comparative experiment was designed,which used two LEDIF detection systems with concave mirror and no concave mirror to detect two amino acids.The results show that the sensitivity of the LEDIF system with concave silver mirror is 16 times that of the system without concave silver mirror,which verifies the effectiveness of the design.In order to achieve the simultaneous detection of multiple targets in the same sample,based on the research of the first system,we take advantage of self-assembly and LED light sources to further design and optimize the instrument(including the optical path,various cuts,etc.)as a whole,thereby increasing the detection throughput.That is,the detection board with two LED-coupled optical fiber units of different wavelengths was manufactured,and the separation of CEs enabled the simultaneous detection of two types of targets in the same sample.The results show that the two types of targets were all detected within 8 minutes,and the sensitivity using dual-wavelength excitation was higher than that using single-wavelength excitation.Finally,the designed dual-wavelength LEDIF-CE enhanced detection system was successfully applied to the simultaneous detection of two types of tumor markers in the real serum of liver cancer patients.It will be applied to the separation and analysis of fluorescent carbon dots(C-dots)for the developed dual-wavelength LEDIF-CE enhanced detection system to further monitor performance and application scope.We explored the synthesis of a new C-dots using m-aminophenol as the raw material,and the C-dots can emit strong fluorescence.After preliminary characterization and observation,the developed system was used to investigate the effect of buffer solution type,concentration,pH,additives,etc.on the separation of C-dots.The surface charge and functional groups of the carbon dot were analyzed and quantitatively analyzed.The results show that the developed dual-wavelength LEDIF-CE enhanced detection system can be well applied in the analysis and characterization of nanomaterials.The method of the system construction provides effective experimental data for further follow-up applications of C-dots.