Iranian researchers from Alzahra University produced an electrochemical DNA biosensor by studying interactions between antimicrobial drug and double stranded DNA on the surface of glassy carbon electrode modified with multi-walled carbon nanotube (MWCNT-DNA-GCE).The most important applications of DNA biosensors are the diagnosis of chemical species such as cancer agents, drugs, and pollutants in water, soil, and herbal samples, which specifically react with DNA.In this study, the interaction between DNA and sulfadiazine was studied on the surface of modified MWCNT-DNA-GCE and MWCNT-GCE electrodes in order to investigate the effect of accumulation time and accumulation potential in the interaction between DNA and sulfadiazine on the surface of MWCNT-GCE. The effects of pH and scanning time were also studied.In their final investigations the researchers studied the effects of DNA volume, the amount of DNA, drawing of calibration curve, limit of detection (LOD), repeatability (RSD%), interruption effect, and the determination of DNA amount in the real sample. Results showed that DNA was measured successfully in the sample injected to human serum by using MWCNT-GCE.The most important applications of DNA biosensors are the diagnosis of chemical species such as cancer agents, drugs, and pollutants in water, soil, and herbal samples, which specifically react with DNA.Results of the research have been published in details in International Journal of Biological Macromolecules, vol. 53, 2013, pp. 101-106.