Electrochemical Aptasensor For The Detection Of Adenosine Based On Carbon Nanomaterials Modified Electrode

Electrochemical biosensor has many advantages,such as fast analysis, simple operation, easy real-time monitoring and automation. But, the development of the electrochemical biosensor, based on enzyme, antigen/antibody, or DNA as a biological recognition, is limited because of the shortcomings of the biological molecular recognition. Aptamer is an oligonucleotide fragment obtained by in vitro screening techniques. Aptamers have attracted a considerable attention due to their ability to bind target protein with high affinity and specificity and have many advantages over antibodies. These properties of aptamers make aptamers ideal candidates as protein recognition elements. In rencetly, the electrochemical aptasensor have been developed rapidly.Carbon nanomaterials have been widely used in field of Analytical Chemistry for their excellent electrical conductivity and good biocompatibility. The introduction of carbon nanomaterials into electrochemical analysis has become a hot point in the field of electroanalytical research,and many innovative achievements have been achieved. As the two outstanding representatives of the family of carbon nanomaterials, carbon nanotubes and graphene have been favored by experts in the field of electrochemistry. The detection sensitivity can be greatly increaseed by coupling carbon nanotubes and graphene with the high specificity of the aptamer and the high sensitivity of the electrochemical recognitions. The main contents are mainly as follows:An electrochemical method for the rapid detection of ractopamine is estanblished, based on the composite material of muti-wall carbon nanotube and graphene (GN-MWCNTs) modified on glass carbon electrode. The results show that GN-MWCNTs composite has a good catalytic effect for ractopamine. The relationship between the oxidation peak current and ractopamine concentration was linear from 0.3 ?mol/L to 20 ?mol/L, the linear equation ipa(?A)=0.2455C(?mol/L)+0.2864(r2=0.9943), with a detection limit of 0.27 ?mol/L.A simple and highly sensitive electrochemical aptasensor for the detection of adenosine, based on the target-induced aptamer displacement and the interaction between the aptamer and the single-wall carbon nanotubes (SWCNTs),was developed. The methyl blue labeled adenosine aptamer(MB-Aptamer) was fixed on the surface of a glass carbon electrode (GCE) modified with the SWCNTs by the interaction between the aptamer and the SWCNTs. In the absence of the adenosine, the strong current signal was observed because of the large number of MB on the electrode. When the adenosine was introduced, the adenosine induced the displacement of the MB-Aptamer from the SWCNTs modified on the electrode into the solution, decreasing the current signal of the aptasensor. The interaction between MB-Aptamer and adenosine was monitored by the cyclic voltammetry (CV) and square wave voltammetry (SWV) using MB as probe. The oxidation peak current of MB using SWV was linear over ranges from 0.0010 to 0.50 nmol/L,with a detection limit of 0.00049 nmol/L.Describes a voltammeetric electrochemical aptasensor array for the determination of adenosine based on the single wall carbon nanotubes (SWCNTs) modified two glass carbon electrodes, using the methylene blue (MB) as signal. The carboxyl functionalized SWCNTs is assembled vertically on glassy carbon electrode using ethylenediamine as the coupling agent. Then, the aptamer was fixed on SWCNTs based on interaction between aptamer and SWCNTs. The results show that the relationship between the current and adenosine concentration was linear from 0.01 to 1.0 nmol/L,with a detection limit of 0.0020 nmol/L (S/N=3).