MMP9 and infection: Ciani et al. [21] developed gold SPE electrodes modified with specific thiolated antibodies for direct detection of infection biomarkers, using electrochemical impedance spectroscopy (EIS), more particularly measuring the charge transfer resistance of FeCN63−/4− on the gold electrode depending on the presence or not of the targeted antigen (TREM-1, MMP-9 and HSL).