A sensitive impedimetric immunosensor for the detection of Interleukin-8 in nasal epithelial lining fluid of asthma patients

Abstract

We report the development of a label-free, affinity-based impedimetric biosensor for the quantitative detection of interleukin-8 (IL-8) present in the nasal epithelial lining fluid (NELF). Early diagnosis of IL-8 in NELF samples enables prognosis of inflammatory respiratory disorders including asthma, chronic obstructive pulmonary disease, and adult respiratory distress syndrome. The study involves the fabrication of an electrochemical biosensor by immobilising polyclonal anti-IL-8 antibody on the anti-fouling zwitterionic hydrogel; polycarboxybetaine methacrylate (pCBMA). The immunosensor was characterised using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), vertical scanning interferometry (VSI) and scanning electron microscopy (SEM). Faradaic EIS measurements were conducted to explore the performance of the immunosensor via changes in charge transfer resistance. The sensor exhibited a good analytical performance in the detection and quantification of IL-8 in complex biological media. The biosensor showed a wide range of IL-8 detection, ranging from 55 fM to 55 nM with a 10 fM limit of detection (LOD). The biosensor showed a high selectivity to IL-8 and 90% reproducibility using untreated NELF samples, with 15-min time to result. These results provide a promising potential for multiplexing the cytokine platform for the profiling, diagnosis and clinical signaturing of associated respiratory disorders.