Fluorescent/Electrochemical Dual-mode Aptamer Sensor For Detection Of Liver Cancer Marker GP73

Golgi Protein 73（GP73）is a novel serum marker used in recent years in clinical medicine for the early diagnosis and screening of hepatocellular carcinoma（HCC）.In this thesis,we introduced nucleic acid aptamer（Apt）,nitrogen-doped graphene quantum dots（NGQDs）,electroactive material reduced graphene oxide-palladium nanoparticles-Prussian blue（RGO-Pd-PB）,and photoelectric nanocomposite molybdenum disulfide-ferrocene-palladium nanoparticles（MoS₂-Fc-PdNPs）with both fluorescence quench and electroactivity for the precise detection of GP73.Single electrochemical,single fluorescence and fluorescence/electrochemical dual-mode detection systems were developed for the accurate and sensitive analysis of GP73 in serum.The main research is divided into the following aspects:（1）Synthesis of characteristic materials:NGQDs with abundant fluorescence properties were prepared by one-step hydrothermal synthesis,RGO-Pd-PB with electroactive material and MoS₂-Fc-PdNPs with photo-electric nanomaterials were prepared by two-step synthesis.The three materials were characterized by ultraviolet spectroscopy（UV-vis）,scanning electron microscopy（SEM）,transmission electron microscopy（TEM）,infrared spectroscopy（FI-IR）,X-ray photoelectron spectroscopy（XPS）,particle size and zeta potential,and their properties in terms of fluorescence and electrochemical detection were analyzed.（2）Research of sandwich-type electrochemical aptamer sensor for GP73 detection:The reduced graphene oxide-palladium nanoparticle-Prussian blue（RGO-Pd-PB）was modified with aptamer to form a recognition probe（RGO-Pd-PB-Apt）,the GP73 aptamer（Apt）was immobilized on the surface of screen-printed electrodes（SPE）modified with gold nanoparticles（Au NPs）to form a capture probe（Apt/Au/SPE）,and then a sandwich-type The detection of GP73 was achieved by an electrochemical sensor with the signal amplification technique of RGO-Pd-PB-like enzyme-catalyzed silver deposition.The sandwich electrochemical sensor was constructed by combining the capture and recognition probes,and the detection of GP73 was achieved by the signal amplification technique of RGO-Pd-PB-like enzyme-catalyzed silver deposition.Under the optimal conditions,the sensor response current difference was linearly correlated with GP73 concentration（1～100 ng/m L）with the calibration equation Y=0.01166-C_GP73+0.6941,R₂ of 0.9835 and LOD of 0.0261ng/m L.（3）Research of fluorescent aptamer sensor for GP73 detection:A fluorescence aptamer sensor based on fluorescence resonance energy transfer（FRET）was constructed using GP73aptamer（Apt）as the recognition element,NGQDs as the fluorescence donor and MoS₂-Fc-PdNPs as the acceptor.The changes of fluorescence intensity within the whole system were measured by fluorescence spectroscopy to realize the analysis of GP73.Under optimal conditions,the relative degree of fluorescence recovery of this sensor was linearly correlated with GP73 concentration（1～10 ng/m L）.The calibration equation was Y=0.02125C_GP73+0.06901,R² of 0.9979 and LOD of 0.812 ng/m L.（4）Research of fluorescence/electrochemical dual-mode aptamer sensor for GP73detection:A fluorescent/electrochemical dual-mode detection system was constructed by GP73 aptamer（Apt）,fluorescent substances NGQDs and photo-electric nanocomposite MoS₂-Fc-PdNPs.Based on this dual-mode sensor,a sensitive dual-mode fluorescence and electrochemical analysis of GP73 in serum was achieved.Under optimal conditions,the difference in response current of this sensor was linearly correlated with GP73 concentration（1～100 ng/m L）,and the calibration equation of Y=0.00298CGP73+0.01074,with the R₂ of0.9964 and LOD of 0.0425 ng/m L;Meanwhile,the relative degree of fluorescence recovery of this sensor was linearly correlated with GP73 concentration（1～10 ng/m L）,and the calibration equation was Y=0.01462C_GP73+0.00804,with the R₂ of 0.9897 and LOD of 0.586ng/m L.The dual-mode sensor has low detection limits,excellent specificity and high stability for GP73 in both fluorescence and electrochemistry.（5）Comparison of three aptamer sensors:the fluorescent aptamer sensor is simple and inexpensive to prepare,the sandwich-type electrochemical aptamer sensor including features high sensitivity and simple device operation.Compared with single fluorescence or electrochemical sensors,the fluorescence/electrochemical dual-mode aptamer sensor has the same detection accuracy as a single sensor,while reducing the possibility of misdiagnosis and underdiagnosis by cross-referencing the two detection results,which is of excellent practicality.