Supersensitive electrochemical sensor for the fast determination of rutin in pharmaceuticals and biological samples based on poly(diallyldimethylammonium chloride)-functionalized graphene

In this work, poly(diallyldimethylammonium chloride) (PDDA)-functionalized graphene (PDDA-Gr) was prepared via in situ reduction of exfoliated graphite oxides in the presence of PDDA. The obtained nanostructure was used as a novel immobilization platform for the electrochemical sensor of rutin. PDDA-Gr has superior electrocatalytic activity for the redox of rutin due to its large surface, fast electron transfer character and strong adsorption effect on rutin. The electron transfer rate constant (ks) and the electroactive surface area were calculated as 1.59 s−1 and 0.3324 cm2 respectively. The saturating absorption capacity (Γ) value of rutin on modified electrode was calculated to be 2.23 × 10−9 mol cm−2. Applying differential pulse voltammetry (DPV), a good linear relationship of the reduction peak current and the concentrations of rutin in the range of 0.0004-1.0 μM was achieved. The detection limit was 0.04 nM (S/N of 3). Under the optimum conditions, the metabolite of rutin, quercetin can be effectively separated from rutin, which suggested the great potential of the proposed method for the practical application in pharmacokinetic and clinical analyses. The method was successfully applied to the fast determination of rutin in medicine tablets and human plasma with satisfactory recoveries.