Leveraging Sodium Iodide for Improved Modification of Conductive Surfaces by an Imidazolium‐Based Poly(Ionic Liquid): Toward Engineering the Electrochemical Enzymatic Biosensors

ABSTRACT The effect of sodium iodide on the adsorption of a poly(ionic liquid)—poly(1‐ethyl‐3‐vinylimidazolium bromide) (PVIm‐Et)—onto conductive (gold and graphite/graphite‐based) supports is examined by means of atomic force microscopy and flow‐through quartz crystal microbalance with dissipation monitoring. The presence of sodium iodide is shown to decisively control the modification of the conductive surfaces by PVIm‐Et, which remarkably enhances with the increasing salt concentration upon adsorption of the polymer. A subsequent binding of an enzyme—glucose oxidase (GOx)—by the PVIm‐Et film is further examined by means of flow‐through quartz crystal microbalance with dissipation monitoring. The amount of bound enzyme is found to correlate well with the efficiency of modification of the conductive surfaces by the polymer. To exemplify the application potential of the polymer‐enzyme films, an electrochemical (amperometric) biosensor for quantification of β‐D‐glucose is constructed, wherein PVIm‐Et is adsorbed in the presence of NaI (60 mM NaI) on a mediator (MnO 2 )‐modified graphite‐based screen‐printed electrode (SPE). The prepared SPE/MnO 2 /PVIm‐Et/GOx biosensor constructs exhibit remarkable analytical performance (a high sensitivity, a low limit of detection, and a broad linear range), demonstrating furthermore excellent stable enzymatic responses over manifold repeated measurements.