Interdigitated Electrode Arrays for Electrochemical Immunosensing of Interleukin-6 in Cerebrospinal Fluid (CSF) and Serum

Electrochemical immunosensors combine the advantages of electrochemical transducers such as low cost, potential for miniaturization, and quantified readout with the selective properties of immunochemical recognition elements. Here we describe a simple, label-free electrochemical immunosensor for the rapid detection of traumatic brain injury (TBI) by quanitifcation of a cytokine interleukin-6 (IL-6) in cerebrospinal fluid (CSF). The sensor system consists of gold interdigitated electrode arrays (IDEAs) that are modified with self-assembled monolayers (SAMs) and IL-6 antibodies (IL-6 mAb) for antigen recognition and capture. Electrode modification was confirmed using surface characterization (FT-IR, fluorescence) and electrochemically via EIS. The sensor performance was evaluated in IL-6 spiked PBS solution: the LOD was determined to be 1.63 pg/mL, with a linear range across 4 orders of magnitude. The sensor exhibits selectivity against non-target cytokines TNF-α and IL-10. The detection of CSF and serum IL-6 using the outlined system will be discussed for use as a point-of-care (POC) diagnostic and prognostic tool for TBI.