Construction Of Aptamer Sensing System And Its Detection Of Pesticide Residues In Traditional Chinese Medicine

Traditional Chinese medicine is a valuable asset to the Chinese nation.With the gradual development of Chinese medicine this year,its unique treatment concept has gradually been accepted by the world.Due to the huge demand and scarcity of wild Chinese medicine resources,artificial cultivation of traditional Chinese medicine has become an inevitable trend.Improper use of pesticides during planting not only affects the quality of Chinese herbal medicines and export trade but also poses a huge hidden danger to human health.Although the traditional pesticide residue detection method has been widely used,this method requires cumbersome sample pretreatment,and most of the required instruments are expensive,difficult to carry,and not suitable for rapid on-site detection.The development of new sensor technologies with rapid detection,sensitivity,accuracy,and convenience is extremely necessary for the detection of pesticide residues.Aptamers and nanomaterials have received wide attention due to their unique advantages.The preparation of aptamers is relatively inexpensive and specific.Nanomaterials can increase the sensitivity of detection.The combination of the two can overcome the limitations of conventional detection and achieve rapid and sensitive detection of pesticide residues in traditional Chinese medicine.The specific work content is as follows:Chapter 1:Based on the nucleic acid aptamer and gold nanoparticles visual detection method to quickly,sensitively and accurately determine the acetamiprid in the medicinal materials.Firstly,according to the literature,the pesticide acetamiprid aptamer was selected as the recognition component,and the gold nanoparticles were used as the color indicator to optimize the experimental conditions(aptamer concentration,salt concentration,nanogold volume,etc.).The high recognition power of the acetamiprid nucleic acid aptamer and the analysis method of the nanogold characteristics are used to detect acetamiprid in the medicinal material.By characterizing the color of the gold nanoparticle system and the change of the UV absorbance value,the detection of the content of acetamiprid in the medicinal material was realized.Under the optimal conditions,the acetamiprid was linearly correlated with the absorption difference in the concentration range of 20~200μg/L,and the correlation coefficient r was 0.9914.In addition,the experimental method was applied to the detection of acetamiprid in the traditional Chinese medicine,and the recovery rate of the test results was good,indicating that the visual sensor prepared in this study can be used for the analysis and detection of acetamiprid in the actual traditional Chinese medicine.The method is simple in operation,high in specificity and high in sensitivity,and has the prospect of on-site detection and development,and also provides a direction for pesticide multi-residue detection.Chapter 2:The acetamiprid electrochemical biosensor was used to detect the residue of acetamiprid in Chinese herbal medicine based on aptamer.The gold electrode was used as the working electrode,and the modified acetamiprid nucleic acid aptamer(SH-Aptamer-MB)was assembled on the surface of the bare gold electrode to optimize the concentration of the aptamer and the reaction time.When acetamiprid,may be made thereto aptamer specifically recognizing such a conformational change,MB apart from the electrode surface,causing current value change.The detection range of the prepared acetamiprid electrochemical sensor is 10~1×10~5 ng/L,the linear equation isΔI=4.615lgC+7.251,the linear regression coefficient r=0.9945,the detection limit is 3.3 ng/L.The method has strong specificity,simple operation and good stability,and can be used for detecting acetamiprid in samples.Chapter 3:Constructing an electrochemical biosensing system combining graphene,nanogold and acetamiprid aptamers to achieve high sensitivity and high selectivity detection of acetamiprid in medicinal materials.The acetamiprid nanobiosensor was prepared by combining graphene,nanogold and aptamer.Optimizing the operating conditions of the sensor,a good linear relationship was observed in the range of acetamiprid 50 to 5 x 10~4 pg/L.The linear equation isΔI=29.98lgC-30.47,the linear regression coefficient is r=0.9977,and the detection limit(S/N=3)is 16.6 pg/L.The method can achieve high sensitivity and high selectivity detection of acetamiprid in the traditional Chinese medicine.Chapter 4:This study established a rapid detection technique for four organophosphorus pesticides based on broad-spectrum organophosphorus aptamers.According to the literature,an aptamer that specifically binds to a specific organophosphorus pesticide is selected as a recognition element,and nano gold is used as a signal transduction element,and an organophosphorus aptamer is bound on the surface of the nano gold particle.Based on the research in the first chapter,an aptamer sensor capable of detecting organophosphorus pesticides was prepared to detect multi-residues of organic phosphorus in medicinal materials.The prepared aptamer sensor has good specificity for phorate,omethoate,profenofos,and limonium.When the residual amount of four kinds of organic phosphorus exceeds 1000μg/L,the solution system turns blue,which can achieve the effect of rapid detection by the eyes,and is suitable for rapid detection on the spot.The development of the sensor provides a new idea for the rapid detection of organophosphorus pesticides.