Abstract SARS-CoV-2 is a matter of concern. Here, biosensors were prepared using iron magnetic nanoparticles containing antibodies against the receptor binding domain (RBD) of the spike protein. Antibodies were adsorbed to nanoparticles in three configurations, including direct adsorption without functionalization (DANPs). Nanoparticles were added to a glassy carbon electrode and connected to an electrochemical cell. Electrochemical impedance spectroscopy and ELISA experiments indicated that antibodies were desorbed from the DANPs upon the addition of the RBD. DANPs-based biosensors produced linear curves with decreasing charge transfer resistance due to the removal of antibodies. Thus, a detection method can be based on antibody desorption.

Graphite powder was mixed to polyurethane, silicon rubber and Araldite® (epoxy) in order to prepare composite materials to be used in the preparation of electrodes. Results showed that voltammetric response could be obtained when at least 50% of graphite (w.w-1) is present in the material. SEM and thermogravimetry were also used in the characterization of the composites.

The use of the quartz crystal microbalance process, electrochemical impedance spectroscopy and surface plasmon resonance for characterizing thin films and monitoring interfaces is presented. The theorical aspects of QCM, EIS and SPR are introduced and the main application areas are outlined. Future prospects of the combined applications of QCM, EIS and SPR methods in the studies of interfacial processes at surfaces are also discussed.