The Reseach Of New Method For Kanamycin And MicroRNA Trace Detection Based On The Electrochemical Sensing

Electrochemical sensing technique is a method for sensing detection based on the electrochemical properties of analytes through converting the chemical quantity of analytes into the electrical quantity.Due to the characteristics of simple,fast,low cost,and high sensitivity,electrochemical sensing has drawn wide attention in the fields of pharmaceutical analysis,environmental monitoring,DNA analysis,pesticide residues and food safety evaluation.In recent years,because of the obvious disadvantages of traditional analytical methods such as require complex preprocessing and low sensitivity in the detection of biological samples,it has earned more and more attentions for developing new methods to achieve the trace detection of drug residues in vivo and detection of cancer's biomarkers in biological sample.With the continuous development of nanotechnology and biotechnology,the electrochemical biosensors based on nanomaterials and aptamer have become powerful candidates which have important clinical significance for clinical monitoring of drugs residues and early diagnosis of cancer.In this dissertation,based on the combination of drug analysis,nano technique,electrochemical technique and biological recognition technique,the aim was focused on the preparation of nano materials,the construction of electrochemical sensing platform and its application for the sensitive and selective detection of drug and cancer biomarkers.The main contents are summaried as follows:1.A facile one-pot synthesis method for polyethyleneimine-functionalized graphene(PEI-G)was created by employing polyethyleneimine(PEI)as both the reductive and functionalized reagent to reduce and wrap exfoliated graphene oxide(EGO)to maintain the single layer status of graphene without aggregation.Based on the fine conductivity of PEI-G and high selectivity of the aptamer specially designed for kanamycin,a novel electrochemical impedance aptasensor for the highly-sensitive and selective detection of kanamycin in serum was fabricated using PEI-G as the electrode substrate to enhance the electrochemical signal and using the aptamer as a biological recognition unit to promote the selectivity.After the specific capture of kanamycin in the sample,the proposed aptasensor exhibited a fine line response for kanamycin within the range of 10 fM to 100 pM with a detection limit of 5.2 fM(S/N=3).Moreover,the proposed aptasensor also displayed a good reproducibility,stability and specificity,which was suitable for the trace kanamycin analyses in a real serum sample.Therefore,this proposed electrochemical impedance aptasensing strategy opens a new insight into potential applications in the clinical diagnostic use of kanamycin.2.Polyethyleneimine functionalized graphene(PEI-G)was prepared through a one-pot synthesis method and then AuNPs/PEI-G composite was prepared through electrostatic interaction between PEI-G and AuNPs.Then the AuNPs/PEI-G composite was used as the substrate of electrode to immobilize the DNA capture probe through the strong S-Au between AuNPs and SH of DNA capture probe.Due to the special recognition of DNA capture probe to microRNA-155,microRNA-155 could be captured onto the surface of electrode and the electrochemical impedance sensor can be constructed through the measurement of impedance value after the capture.At the optimized experimental condition,the impedance value and logarithm of concentration of microRNA-155 gave a fine linear relationship within the range of 1-1000 nM with a detection limit of 0.51 nM(S/N=3)and it is expected to be used for the detection of microRNA-155 in the real sample of serum.