Design of Aptamer-Based Optical Nanosensors for the Detection of Interleukin-6

Abstract

Interleukin-6 (IL-6) is an inflammatory cytokine that has been recognized as a potential target for various autoimmune diseases, chronic inflammatory conditions, cancers, and more. Dysregulation of IL-6 is implicated in the genesis and progression of these disease states. For these reasons, detection of IL-6 and related biomolecules in vivo is of clinical interest to researchers of cancer and other inflammatory diseases. Single-walled carbon nanotubes (SWCNT) possess unique near-infrared fluorescent properties. When functionalized with a molecular recognition element, SWCNT can act as optical sensors that respond sensitively and specifically to a target analyte. Both antibodies and DNA aptamers can serve as molecular recognition probes, but aptamers may hold advantages for certain sensing applications due to their smaller size, higher stability, and lower production cost. We functionalized SWCNT with an analyte-specific DNA aptamer, which resulted in a nanosensor which responds selectively to IL-6. In vitro testing revealed significant shifts in the center wavelength and intensity of SWCNT fluorescence in response to IL-6. We then conducted several studies to investigate the mechanism of this sensor response in order to compare against traditional antibody-based sensors prior to ex vivo clinical sample testing. Rapid, minimally invasive detection of IL-6 as a chronic disease biomarker in vivo through DNA aptamer-functionalized SWCNT holds promise for early disease diagnosis, observation of disease progression, and evaluation of response to therapy.