Electrochemical Behavior Of Adrenaline And Its Interaction With DNA

Epinephrine （Ep） is an important catecholamines secreted by the adrenal medulla, mainlypresent in the sympathetic nerve cells, central nervous system and adrenal medulla. It plays animportant role in cardiovascular function and catabolism. Its metabolic disorder often leads tothe occurrence of certain diseases. In addition, DNA as genetic information storage and carriers,it is usually as target molecule of some drugs. Therefore, to study the determination methods forEp and study the Ep interaction with DNA have important theoretical value and practicalsignificance in clinical medicine and biochemistry.The electrochemical behaviors of Ep and its determination were studied on phosphateactivated glassy carbon electrode and the glassy carbon electrode （GCE） modified withhexadecyl trimethyl ammonium bromide （CTAB）/multi-wall carbon nanotubes （MWNTs）composite membrane. The electrochemical behaviors of Ep and the interactions of epinephrinewith DNA were also studied on a glassy carbon electrode modified with Au nano-particles. Theresults are as follows:1. Phosphate activated glassy carbon electrode was prepared by cyclic voltammetry andthe electrochemical behaviors of Ep were studied at the phosphate activated electrode. Theexperimental results show that epinephrine has sensitive oxidation peak currents in pH=6.0phosphate buffer solution. Based on the relationship of the oxidation anodic peak current of Epand its concentration in the range of1.0×10^-61.2×10^-5mol/L, a voltammetric method fordetermination of epinephrine was set up. The linear regressive equation was ipa(×10^-4A)=0.5346CEp(×10^-5mol/L)+0.6457with r=0.9984. The detection limit（S/N=3） was3.0×10^-7mol/L. The interference of uric acid could be diminished in this method. Compared with somechemical modified electrode, the proposed method eliminates the cumbersome modificationprocesses, and it showed high good sensitivity and selectivity, which has been applied to theinjection sample analysis with satisfaction.2. The glassy carbon electrode modified with hexadecyl trimethyl ammonium bromide/multi-wall carbon nanotubes composite membrane was prepared by casting method, and theelectrochemical behaviors of epinephrine at this modified electrode. The composite membranecan be used to determination of Ep and ascorbic acid （AA） and eliminate the interferences foreach other of them because the electro-static interaction between CTAB and positively chargedEp and negatively charged AA made the peak-to-peak separation of Ep and AA reach to256mV.The electrochemical method for determination of Ep in the presence of high concentration ofAA, and for determination of AA in the presence of Ep was set up. The proposed method wasapplied to determination the content of Ep and AA in injections with simplicity, good selectivity and high sensitivity.3. The interactions of epinephrine with double strand DNA （dsDNA） and single strandDNA （ssDNA） were studied in Mcllvaine buffer solution or on a glassy carbon electrodemodified with Au nano-particles. The glassy carbon electrode modified with Au nano-particleswas prepared by a constant potential deposition method. The results showed that, in Mcllvainebuffer solution, the ssDNA made the peak current of Ep at the Au nano-particles modified GCE（nanoAu/GCE） decrease more than the same concentration of dsDNA. However, when the sameamount of dsDNA or ssDNA was immobilized on the surface of nanoAu/GCE, a relative largerpeak current of Ep was obtained for the ssDNA than for the dsDNA. The results showed thatthe ssDNA could combine with more Ep than dsDNA. Some electrochemical parameters (suchas electron transfer coefficient （α）, the standard rate constant of the electrode reaction （Ks）, thebinding ratio of Ep with DNA, the equilibrium constant （β） related to Ep in the absence orpresence of DNA were studied. The differences of the combination make Ep have potential useas an indicator for detecting the DNA hybridization. The quantitative analysis of DNA wasstudied based on the linear relationship between the declination of oxidation current of Ep andthe concentration of DNA within a certain concentration range.