Advancing electrochemical biosensors for interleukin-6 detection

IL-6 is a pleiotropic cytokine that exerts pathological proinflammatory effects in various acute, chronic, and communicable diseases. These diseases place a significant burden on individuals, healthcare, and economic systems; thus, rapid and low-cost diagnosis and prognosis sensor systems are urgently needed. In this review, we critically evaluate electrochemical sensors for detecting IL-6 in different biofluids. First, we investigate the roles of IL-6 structure, binding, and pathways in various pathologies and observe that detectable levels of IL-6 are present in different biofluids. Second, we discuss the functionalization and sensing approaches of electrochemical sensors using (1) antibodies, (2) aptamers, (3) IL-6 receptors, and (4) molecularly imprinted polymers for the selective detection of IL-6 with practical detection levels and wide linear ranges. Third, we explain unexpected IL-6 sensing results caused by possible interactions between sensor components, the sample environment, and IL-6 that may provide an excellent scope for future research. Finally, we believe that fabricating reliable and non-invasive IL-6 sensors with exceptional efficacy will facilitate the development of portable diagnostic and monitoring systems that may accelerate the detection speed worldwide.