Showing papers by "Samo B. Hočevar published in 2022"

The Effect of Preconditioning Strategies on the Adsorption of Model Proteins onto Screen-Printed Carbon Electrodes

Abstract: The preconditioning and modification of the supporting electrode surface is an essential step in every biosensor architecture. In particular, when using screen-printed carbon electrodes (SPEs) as inexpensive and convenient disposable sensor substrates, their somewhat lower electrochemical (surface) reproducibility might represent a complex hurdle. Herein, we investigated the effect of selected preconditioning strategies, such as cyclic voltammetric pretreatment, in H2SO4 and H2O2 and plasma pretreatment with a positive and negative glow discharge, which all improved the electrochemical stability of the unmodified SPEs. Furthermore, we studied the influence of preconditioning strategies on the adsorption kinetics of the two most commonly used building blocks for biosensor preparation, i.e., bovine serum albumin (BSA) and protein A. We observed an advantageous effect of all the examined preconditioning strategies for the modification of SPEs with protein A, being the most effective the negative glow discharge. On the other hand, BSA exhibited a more complex adsorption behavior, with the negative glow discharge as the only generally beneficial preconditioning strategy providing the highest electrochemical stability. Protein A revealed a more substantial impact on the electrochemical signal attenuation than BSA considering their same concentrations in the modification solutions. For both BSA and protein A, we showed that the concentrations of 5 and 10 μg mL−1 already suffice for an electrochemically satisfactorily stable electrode surface after 60 min of incubation time, except for BSA at the positive-plasma-treated electrode.

An In Situ AFM Study of Electrochemical Bismuth Film Deposition on a Glassy Carbon Substrate Electrode Using a Low Concentration of Bismuth Ions

Abstract: The bismuth film electrode (BiFE), which was first introduced in 2000 for electrochemical stripping analysis, is now widely used in electroanalytical laboratories worldwide. Numerous scientists have been inspired to conduct more research and broaden the understanding of the BiFE’s favourable electroanalytical performance, which is comparable to, or in some cases even exceeds, that of its mercury counterparts for the detection of heavy metal ions and selected organic compounds. Various types of bismuth-based paste electrodes, as well as in-situ and ex-situ prepared BiFE, have been presented in combination with potentiometric and voltammetric (stripping) protocols. Whereas the ex situ prepared electrodes must be moved from the modification solution to the measuring cell device and often need to display improved stability for several measurements, the ex-situ-prepared bismuth films require acceptable physical and chemical stability. In this study, we provided insight into the commencement of the formation of the bismuth film on a glassy carbon substrate electrode (GCE) when using a very low concentration of bismuth ions. We used our home-constructed AFM cell to fit in commercial working GCE, a platinum wire as the counter electrode, and an Ag/AgCl/NaCl (3 M) as the reference electrode.