Research For DNA Electrochemical Sensor Used For Detection Of Hepatitis B Virus

Detection of special DNA sequence in biological samples such as blood, organ and body fluid has great significance in biomedicine field. The result of detection can be used to identify and detect genetic or contagious ailment. DNA sensor is a new kind of biosensor developing for the above purposes.The DNA electrochemical sensor was prepared by self-assembling the designed hepatitis B virus DNA specific probe on the surface of Au electrode together with Hoechst 33258 as electro-active indicator. The condition for self-assemble single-molecular film was chosen during experiments as the following: probe concentration is 100 μ g/mL, self-assemble time is 12 hours. The voltammetry characteristic of single-strand DNA modified electrode was observed in 0.5 mol/L KC1. The electron-transfer capability of single-strand DNA modified electrode was observed in 5mmol/L Fe(CN)63+/Fe(CN)64+.The prepared DNA electrochemical sensor was used to determine the nature and quality of complementary DNA of standard concentration. Then the DNA sensor was used to diagnose the clinical blood sample containing hepatitis B virus. While detecting the hybridization of DNA sensor with complementary DNA of standard concentration, the effect of hybridization times hybridization temperature , selection of indicator, intercalation time, washing time and electrochemical scan condition to the detection result was discussed. The result shows that Hoechst 33258 is a kind of indicator with high specificity. The optimized response of indicator can be got while hybridization time is 90min, hybridization temperature is 25℃and NaCl in hybridization solution is 0.3mol/L. While detecting the complementary DNA of standard concentration, the lower limit is 10ng/mL. In the range of 0.05-1 μ g/mL, there was a simple equation between the respond signal of indicator and the concentration of complementary DNA. The fundamental characteristic such as stability,specificity , life span was also tested. The detection for clinical blood serum shows that DNA electrochemical sensor can find out the hepatitis B virus DNA inblood serum, and the relative concentration of DNA was consistent with that abtainedby fluorescence polymerase chain reaction.