A general route to nanostructured M[V3O8] and Mx[V6O16] (x = 1 and 2) and their first evaluation for building enzymatic biosensors

Abstract

In order to develop novel electroactive hosts for biosensor design, the possibility to use nanostructured vanadate phases as alternatives to well-known V₂O₅ gels was studied. For this purpose, the formation of M[V₃O₈] and M_x[V₆O₁₆] (x = 1 and 2) oxides by the sol–gel process has been studied over a wide range of cations (M⁺ = Li⁺, Na⁺, K⁺, Cs⁺, and NH₄⁺; M²⁺ = Ca²⁺, Mg²⁺ and Ba²⁺). By a combination of XRD, ⁵¹V NMR and SEM studies, it was possible to evidence the influence of the nature and hydration state of cations on the size and morphology of the resulting particles as well as on the kinetics of their formation. On this basis, K₂[V₆O₁₆] was evaluated for glucose oxidase encapsulation, either via impregnation or co-precipitation methods. When compared to V₂O₅, these novel bioelectrodes exhibit higher stability under pH conditions of optimum enzymatic activity, as well as better sensitivity, and reproducibility for glucose detection via amperometric titration.