Construction Of Lead Ion Electrochemical Detection Electrode Based On Nucleic Acid Aptamer

Background:Heavy metal pollution is a major threat to human health and environmental safety.Lead(Pb²⁺),as a major heavy metal pollutant,can cause a variety of neurotoxic reactions in humans（especially children）,including anemia,memory loss,irritability,and mental retardation.Therefore,accurate,sensitive,and immediate on-site monitoring of Pb²⁺is essential for environmental and food safety as well as clinical toxicology.At present,the detection of lead ions,such as graphite furnace atomic absorption method,inductively coupled plasma mass spectrometry,chemiluminescence method,etc.,are limited by large-scale detection instruments,and the research that can be used for on-site real-time detection technology is very scarce.The electrochemical sensor is an emerging detection method,which has the advantages of small size,easy portability,fast response,and simple operation.Aptamers are a new type of sensor recognition element that has been widely used in recent years.They have higher thermal stability than antibodies and are easy to synthesize and modify.Objectives:Based on the above background,this project aims to construct an electrochemical detection electrode based on nucleic acid aptamer technology that can be applied to the immediate detection of lead.Methods:（1）The effects of four commonly used dispersants on the solubility of multi-walled carbon nanotubes and the electrochemical properties of the modified carbon nanotubes were investigated,and the best dispersant suitable for the dispersion and modification of multi-walled carbon nanotubes was determined.（2）The selected carbon nanotube dispersions were applied while nanogold was modified on the electrode surface by electrodeposition,and lead ion detection electrodes were prepared using single-stranded DNA based on the label-free method to evaluate the linearity,precision accuracy,selectivity,and stability of the electrodes.（3）To construct electrochemical sensors based on redox probes using double-stranded complementary DNA that can be directly used for sample analysis,optimize the modification conditions as well as the electrode detection conditions,and evaluate the linearity,and precision accuracy,selectivity,and stability of the electrodes.Result:This topic explores the improvement of the solubility of carbon nanotubes by different dispersion methods,and at the same time explores the effect of different dispersions on electrode modification,and selects the most suitable carbon nanotube dispersion for electrode modification.A label-free single-stranded aptamer lead ion detection electrode was prepared.The standard curve is:?I=12.06*（lg C）+14.13,R²is 0.9276,detection limit is 1ng/m L,detection limit It is 0.1ng/m L.A highly sensitive and selective lead ion detection electrode based on double-stranded DNA was prepared,which can be directly used for sample detection.Its standard curve is?I=3.605*lg（C）+2.926.R² is 0.9159.Conclusion:In this study,Nafion,a solvent suitable for multi-walled carbon nanotubes,was screened out.The dispersed carbon nanotubes had small particle size and good stability,which played a good gain for electrode modification.The label-free electrochemical sensor constructed based on nucleic acid aptamers in this study can specifically and accurately quantify lead ions in biological samples.The labeled redox probe double-stranded DNA electrochemical detection electrode constructed in this study can be directly applied to sample analysis.