acid (95–98% ACS Reagent), hydrogen peroxide 30% (w/w) solution,
ethanol, 2-(N-morpholino)ethanesulfonic acid (MES),
phosphate buffered saline (PBS, pH 7.4), monoclonal anti-interleukin-6
antibody, Tween 20, bovine serum albumin (lyophilized), potassium
ferricyanide, potassium ferrocyanide, lithium perchlorate, human interleukin-6
(recombinant, expressed in E. coli, lyophilized),
human interleukin-10 (recombinant, expressed in E. coli, lyophilized), and human serum (heat-inactivated, clotted from whole
blood) were purchased from Millipore Sigma. IgG H&L Alexa Fluor
568 (Abcam), human TNF-α (recombinant, expressed in E. coli, lyophilized, PeproTech), pooled human cerebrospinal
fluid (Innovative Research), and Au interdigitated electrodes on glass
(10 μm digit/gap, Metrohm Dropsens) were also used. Aqueous
solutions were prepared using deionized (DI) water (ρ = 18.2
MΩ cm) from a Millipore Milli-Q system.