Lithographically Patterned PEDOT Nanowires for the Detection of Iron(III) with Nanomolar Sensitivity

Arrays of nanowires of an electronically conductive polymeric affinity medium tailored to the detection of Fe(III) are prepared, and their properties for detecting Fe(III) are evaluated. This polymeric affinity medium consists of poly(3,4-ethylenedioxythiophene) (PEDOT) into which an iron chelator, deferoxamine (DFA), has been doped during the polymerization process. PEDOT-DFA nanowires are potentiostatically deposited from a solution containing both EDOT and DFA using lithographically patterned nanowire electrodeposition (LPNE). The through-nanowire electrical resistance of PEDOT-DFA nanowires is measured as a function of the Fe(III) concentration. In parallel with measurements on PEDOT-DFA nanowire arrays, the electrochemical impedance of PEDOT-DFA films is characterized as a function of the Fe(III) concentration and the frequency of the impedance measurement in order to better understand the mechanism of transduction. PEDOT-DFA nanowires detect Fe(III) from 10(-4) to 10(-8) M with a limit of detection of 300 pM (calculated) and 10 nM (measured).