SERS-based self-calibrating aptamer sensor for selective detection of IL-6

The cytokine interleukin-6 (IL-6) is closely associated with the inflammatory response and is also an important marker for many inflammatory diseases. Therefore, it is crucial for clinical inflammation diagnosis to detect IL-6 with high sensitivity and selectivity. For this, we developed an aptamer sensor based on surface-enhanced Raman spectroscopy (SERS) to detect IL-6. Through the recognition-release mechanism, with the releasing process of SERS signal molecules, the SERS signal can be changed by IL-6-triggered. Meanwhile, the sensor utilized two SERS signal molecules, cyanine 3 (Cy3) and 4-mercaptobenzonitrile (MBN), to construct a dual-signal self-calibration model, which can greatly avoid the environmental interference of biomolecules, including proteins, and achieve the IL-6 quantification. This enables the aptamer sensor to reliably and sensitively detect IL-6 within a linear range of 10−9 mg/mL-10−5 mg/mL (R2 =0.961) and a minimum limit of detection (LOD) of 0.056 pg/mL. Furthermore, the application of a biointerference-free reporter allows to specifically detect IL-6 (5 pg/mL) from complex serum samples. Therefore, this aptamer sensor can be applied to the detection of IL-6 in the clinic and has the potential to be an alternative tool for the diagnosis of early inflammation.