Studies On The Fabrication Of Electrochemical Aptasensor Based On The Ternary Surface Structure And Its Property

Electrochemical aptasensor have attracted great attention due to itspotential application in clinical diagnosis and drug screening. Theproperty of the electrode surface shows a big impact on the stability,efficiency and sensitivity of the aptasensor. Therefore, pursuing the wayto control the surface of electrode is of significance. In this thesis, wefocus on the way to improve the sensitivity of electrochemical aptasensorthrough control of electrode surface. The main work is described asfollows:(1) Based on a ternary surface component containing aptamer,dithiothreitol (DTT) and6-mercapto-1-hexanol (MCH), an ultrasensitiveelectrochemiluminescence (ECL) aptasensor was designed for thedetection of lysozyme with dichlortris (1,10-phenanthroline) ruthenium(II) hydrate (Ru(phen)2+3) as the ECL probe and2-di-nbutylanino-ethanol(DBAE) as the coreactant. Under the optimal experimental conditions,the changes in ECL intensity (ΔIECL) increased linearly with the logarithmof the lysozyme concentration in the range from0.02pg/ml to8pg/ml (R=0.994) and the limit of detection was0.01pg/mL. In comparison, thelinear range of the aptasensor fabricated by aptamer and MCH was from0.5ng/ml to8ng/ml (R=0.996) and the limit of detection was0.1ng/mL.The results indicated that the proposed aptasensor showed improved thehigh sensitivity and stability.(2) Based on a ternary surface structure consisting of the aptamer,dithiothreitol (DTT) and6-mercapto-1-hexanol (MCH), an ultrasensitiveelectrochemical impedance spectroscopic (EIS) aptasensor was designedfor the detection of adenosine. Under the optimal experimental conditions,the changes in the charge-transfer resistance (ΔRct) increased linearlywith the logarithm of the adenosine concentration in the range from0.05pM to17pM（R=0.995) and the limit of detection was0.017pM. Incontrast, the EIS aptasensor fabricated with only the DTT, the linearrange was from0.5pM to27pM (R=0.998) and the limit of detectionwas0.17pM. Moreover, the property of aptasensor fabricated withoutdithiothreitol was also investigated. The results suggested the ternarystructure could effectively improve the sensitivity and selectivity of theEIS aptasensor.(3) Based on a ternary surface modification which fabricated by theaptamer, dithiothreitol (DTT) and6-mercapto-1-hexanol (MCH), anultrasensitive differential pulse voltammetry (DPV) aptasensor wasdesigned for the detection of adenosine. Under the optimum experimentalconditions, the linear range between the change in current (ΔI) and the concentration of lysozyme entended from0.05pM to9.1pM (R=0.999)and the limit of detection was0.02pM.