Noble metal dispersed multiwalled carbon nanotubes immobilized ss-DNA for selective detection of dopamine

A hybrid nanocomposite consisting of Pt nanoparticles decorated functionalized multiwalled carbon nanotubes (f-MWNT) immobilized with single strand-DNA (ss-DNA) has been devised for the selective detection of dopamine (DA). AFM and TEM analyses show that wrapping of ss-DNA over Pt/f-MWNT reduces the aggregation of the nanotubes arising from van der Waals interaction. In addition to serving as a noncovalent dispersion agent, ss-DNA facilitated electron transfer towards dopamine, as analyzed by cyclic voltammetric studies (CV) and amperometry. The sequence dependency of ss-DNA for DA detection has been analyzed using AC and GT ss-DNA. The hybrid nanocomposite biosensor consisting of AC/ss-DNA exhibits linearity of detection upto similar to 315 mu M, with a detection limit 0.8 mu M towards dopamine. The best sensing performance with linearity of similar to 800 mu M and detection limit similar to 0.45 mu M has been obtained with GT/ss-DNA immobilized Pt/f-MWNT sensor. Further, the nation coated ss-DNA wrapped Pt/f-MWNT immobilized biosensor exhibits good stability, fast response time (<3 s) and selective detection of DA in the presence of ascorbic acid and uric acid. (C) 2011 Elsevier B.V. All rights reserved.