An optical fiber based immunosensor for localized detection of IL-1β in rat spinal cord

Sensitive and localized measurements of cytokines is important in biomedicine as cytokines are produced locally where needed to induce an immune reaction. Here, we present a novel immunosensor deposited on the optical fiber surface. The sensor is capable of localized detection of interleukin-1beta (IL-1β) in the rat spinal cord. In this immunosensor, a stable immunocapture surface was formed via a biotin-streptavidin coupling strategy and fluorescent carboxylated supermagnetic iron oxide (SPIO)-IL-1β detection antibody conjugates were used for signal amplification. Under the optimal condition, the proposed immunosensor can be used for the estimation of IL-1β in vitro in the range from 3.13 pg.mL⁻¹ to 400 pg.mL⁻¹ with a detection limit of 1.12 pg.mL⁻¹. Furthermore, the performance of the fiber sensor was firstly assessed by ex-vivo monitoring the secretions of the rat macrophages stimulated by lipopolysaccharide (LPS), and the results demonstrated significant correlations with a commercial ELISA kit. Furthermore, the fiber sensor was successfully utilized to carry out a localized measurement of IL-1β in a spinal cord of an anesthetized rat. The result indicates that such fiber sensors can be used as an effective and sensitive tool for localized detection of IL-1β in vivo, in a range of research and clinical applications.