Polyadenine-mediated aptamer-conjugated gold nanoparticles for the detection of interleukin-6

Acting as a pivotal cytokine of innate immunity, the signal transduction of interleukin 6 (IL-6) is always elevated in relation to the occurrence of injury, bacteria and chemical invasion. IL-6 as a critical care biomarker can be used for the clinical diagnosis of diseases ranging from bacterial infections to most inflammatory reactions. Then, a simple, cost-effective and sensitive colorimetric aptasensor was designed for the specific detection of IL-6. The IL-6 aptamer anchored on gold nanoparticles (AuNPs) by polyadenine accurately recognized IL-6, and then, the folded IL-6 aptamer enhanced the stability of AuNPs against salt-induced aggregation. The degree of AuNP aggregation increased inversely with the concentration of IL-6. A higher IL-6 content resulted in lower aggregation of AuNPs, which can be measured by spectrophotometry. The results showed that the proposed aptasensor exhibited a linear detectable range of 7-500 pg mL^-1 with a limit of detection of 4.652 pg m^-1. Furthermore, this proposed colorimetric aptasensor achieved the discrimination of IL-6 from other analogues and could detect IL-6 in human serum samples, which demonstrated its potential application for the detection of IL-6 in complex matrices.