A flow-based diagnostic approach for early inflammation detection in clinical settings

Interleukin-6 (IL-6) is an important cytokine that plays a significant role in tumour growth and angiogenesis in various malignant tumours. Here, an integrated fluidic immunosensor capable of detecting the concentration of IL-6 protein in fetal bovine serum (FBS) samples using an electrochemical method in a fluidic biochip fabricated on screen-printed carbon electrodes (SPCEs) is presented. To improve the performance of the immunosensor, the SPCEs was modified with multi-walled carbon nanotubes-poly(allylamine hydrochloride)/gold nanoparticles (MWCNTs-PAH/AuNPs), which improves antibody IL-6 attachment and electron transfer efficiency. The morphological and structural properties of the nanocomposites were characterised by scanning electron microscopy (SEM) and Raman spectroscopy, while electrochemical properties were evaluated using cyclic voltammetry (CV) and square wave voltammetry (SWV). Under optimal conditions, the immunosensor exhibited a linear detection range for IL-6 protein from 0.001 to 0.1 ng mL^-1, with a limit of detection 0.05 pg mL^-1. Tests were performed to assess reproducibility, stability and selectivity for IL-6 in FBS samples. This immunosensor provides a sensitive, minimally invasive and simple method for the determination of clinical IL-6 protein levels. Compared to the traditional IL-6 protein batch sensor method, the approach provided by this integrated fluidic immunosensor higher sensitivity, reproducibility and faster detection.