| dc.description.abstract | Interleukin-6 (IL-6) is an inflammatory cytokine involved in the immune response but when dysregulated becomes problematic. We are interested in IL-6 due to its involvement in preterm birth, musculoskeletal infection, and endometriosis. The development of sensors to rapidly and sensitively detect relevant protein biomarkers can provide insight into poorly understood conditions like preterm birth and endometriosis and also drastically improve patient outcome in cases of musculoskeletal infection. Here, three methods for the development of an electrochemical sensor for interleukin-6 (IL-6) were investigated. The three sensor designs are: electrochemical aptamer based sensors, a competitive immunoassay using alkaline phosphatase (AP) and p-aminophenyl phosphate (PAPP), and a competitive and sandwich immunoassays using horseradish peroxidase (HRP) and tetramethylbenzidine (TMB). The aptamer-based sensors investigated were not stable or replicable and their response varied depending on the solution they were in so they cannot be used in complex samples. Competitive assay measurements utilizing the AP/PAPP system were variable, likely due to polymerization and adsorption of p-aminophenol (PAP), the enzymatic product used to quantify amounts of IL-6. We characterized the electrochemical behavior of PAP directly to confirm this. We discovered that these effects are concentration-dependent and by carefully controlling PAP production, the variability in assay measurements can be minimized. The sandwich immunoassay using HRP/TMB demonstrated good replicability, decreased the amount of time for concentration readout to approximately one hour, achieved detection with sufficient sensitivity in the desired range of 100-1000 pg/mL, and demonstrated good response in complex solutions. As a result, the sandwich immunoassay using HRP/TMB is most promising for detection of IL-6 in biological samples. | |
