Development of a needle shaped microelectrode for electrochemical detection of the sepsis biomarker interleukin-6 (IL-6) in real time

Recent Advances in Electrochemical and Optical Biosensors Designed for Detection of Interleukin 6

“…This is analogous to direct enzyme linked immunoassay (ELISA) approach which produces fluorescence when the antigen and antibody complexes are formed. Antibodies against IL-6 can be directly immobilized on the surface of a functionalized electrode [100] or nano-features can be introduced in the sensing layer [101][102][103] for signal amplification purposes as shown in Figure 2. A robust dECIA method with a wide linear range was demonstrated by Tertis et al [101], and aptamer against IL-6 was immobilized on polypyrrole nanoparticles (PPy) decorated with gold nanoparticles (AuNPs) of 50 nm diameter.…”

“…Different sensing mechanisms developed for IL-6 detection. Direct electrochemical immunoassay (ECIA) based on IL-6 and the primary antibody (Ab 1 ) interaction [100]; using a conjugate of polypyrrole-Au Nanoparticles-aptamer [101]; carbon nanotubes (CNTs) coated with (Ab 1 ) [102]; carbon nanotubes coated with gold nanoparticles (AuNPs) and (Ab 1 ) [103]. Indirect electrochemical immunoassay in which a competitive antigen bound to AgNP-coated Polystyrene nanobeads [104].…”

“…The geometry of the electrode's surface plays a pivotal role in preventing the counter-ions screening at the double layer [123], and a concave surface promotes efficient electron transfer kinetics, thereby increasing the sensitivity of the sensor. An array of eight gold disc-shaped microelectrodes was engraved on a silicon needle with an objective of real-time in-situ monitoring of IL-6 [100] ( Figure 4A). This approach was envisioned following the development of a robust microelectrode-based electrochemical sensing platform for chemical and DNA sensing applications [124][125][126][127].…”

“…Different schemes of sensing layer, as discussed earlier, were proposed with an aim to amplify the readout signal which ultimately improves sensitivity and dynamic range of biosensor. Some of the effective approaches which significantly boost the outgoing signals of sensor are (1) modification of electrode geometry and size [100]; (2) coating of electrode with nano-features, such as SWCNT, AuNP, and Polypyrrole nanoparticles [101][102][103][104]; and (3) labeling of conjugate in sandwich configuration with nanoparticles, enzymes or a combination of two [105,106,[108][109][110] (Figure 4A). Figure 4B shows a comparison of intensity of readout signal against the least concentration detected by each configuration, i.e., direct and sandwich electrochemical immunoassay.…”

Biomarkers for Point-of-Care Diagnosis of Sepsis

“…Nevertheless, progress has been made with the development of biosensors that can be incorporated into these devices for the measurement of biomarkers such as PCT [124]. Recent work has led to the development of a microelectrode sensor for the measurement of IL-6 with an assay time of around 2.5 min [125]. Work on more novel biomarkers has also been done by Min and co-workers [126], who developed a biosensor for the measurement of IL-3 and have attempted to validate its use in a small cohort of septic and control patients.…”