title: Protein detection with potentiometric aptasensors: a comparative study between polyaniline and single-walled carbon nanotubes transducers.
abstract: A comparison study on the performance characteristics and surface characterization of two different solid-contact selective potentiometric thrombin aptasensors, one exploiting a network of single-walled carbon nanotubes (SWCNTs) and the other the polyaniline (PANI), both acting as a transducing element, is described in this work. The molecular properties of both SWCNT and PANI surfaces have been modified by covalently linking thrombin binding aptamers as biorecognition elements. The two aptasensors are compared and characterized through potentiometry and electrochemical impedance spectroscopy (EIS) based on the voltammetric response of multiply charged transition metal cations (such as hexaammineruthenium, [Ru(NH3)6](3+)) bound electrostatically to the DNA probes. The surface densities of aptamers were accurately determined by the integration of the peak for the reduction of [Ru(NH3)6](3+) to [Ru(NH3)6](2+). The differences and the similarities, as well as the transduction mechanism, are also discussed. The sensitivity is calculated as 2.97 mV/decade and 8.03 mV/decade for the PANI and SWCNTs aptasensors, respectively. These results are in accordance with the higher surface density of the aptamers in the SWCNT potentiometric sensor.
authors.affiliation: Department of Analytical and Organic Chemistry, Universitat Rovira i Virgili, Campus Sescelades, Marcel · lí Domingo, 43007 Tarragona, Spain. ali.duzgun@urv.cat
authors.forename: Ali
authors.initials: A
authors.lastname: Düzgün
authors.forename: Hassan
authors.initials: H
authors.lastname: Imran
authors.forename: Kalle
authors.initials: K
authors.lastname: Levon
authors.forename: F Xavier
authors.initials: FX
authors.lastname: Rius
mesh_terms: D000814:Aniline Compounds / Q000737:chemistry*; D015374:Biosensing Techniques / Q000379:methods*; D058266:Dielectric Spectroscopy; D006801:Humans; D036103:Nanotechnology / Q000379:methods; D037742:Nanotubes, Carbon / Q000032:analysis* / Q000737:chemistry; D010084:Oxidation-Reduction; D011199:Potentiometry / Q000379:methods*; D011485:Protein Binding; D017975:Ruthenium Compounds / Q000737:chemistry; D012680:Sensitivity and Specificity; D055672:Static Electricity; D013499:Surface Properties; D013917:Thrombin / Q000737:chemistry / Q000302:isolation & purification*; D014159:Transducers
chemical_list: D000814:Aniline Compounds; D037742:Nanotubes, Carbon; D017975:Ruthenium Compounds; C416807:polyaniline; C031584:hexammineruthenium; D013917:Thrombin