ИСТИНА

A one-pot synthesis of polyaniline (PANI) in the presence of exfoliated graphite platelets of graphite and graphene results in a composite material PANI-graphene and PANI-graphite. Cyclic voltammetric measurements with the Ru(NH3)62+/3+ and Fe(CN)63-/4- redox couples have shown that the composite materials are electroactive at neutral pH, in contrast to conventional PANI prepared without graphene/graphite. This indicates that graphene/graphite platelets are uniformly distributed within the PANI matrix forming an electrically conducting network. Moreover, the incorporation of graphene or graphite platelets in the composite material improves its pH stability and it can be therefore used as an ion-to-electron transducer in solid-contact ion-selective electrodes (SC-ISE) or as an electrocatalytic film electrode for the detection of biological molecules at physiological pH. We have shown that PANI-graphene films can be used for amperometric detection of sodium ascorbate at pH 7.3 which results in a current amplification of 1.3–10.2 times in the concentration range of 10^-4–10^-2 M, compared to conventional PANI. This clearly demonstrates the advantage of incorporating exfoliated graphites in the PANI films. We show that PANI-graphene based Ca2+ -selective SC-ISEs had low detection limit of 5x10^-9 M which indicates that they can be applied in inorganic trace analysis.