Chitosan/genipin modified electrode for voltammetric determination of interleukin-6 as a biomarker of sepsis

• Published in: International journal of biological macromolecules 2023-01, Vol.224, p.1450-1459
• Main Authors: de Matos Morawski, Franciele, Dias, Greicy Brisa Malaquias, Sousa, Kelline Alaide Pereira, Formiga, Rodrigo, Spiller, Fernando, Parize, Alexandre Luis, Báfica, André, Jost, Cristiane Luisa
• Format: Article
• Language: English
• Subjects: Animals; Biomarkers; Biosensing Techniques - methods; Chitosan; Cytokine immunoassay; Electrochemical immunosensor; Electrochemical Techniques - methods; Electrodes; Fluorine tin oxide; Immunoassay - methods; Interleukin-6; Limit of Detection; Mice; One-drop analysis; Sepsis; Square wave voltammetry
• ISSN: 0141-8130; 1879-0003
• DOI: 10.1016/j.ijbiomac.2022.10.232

Ultrasensitive electroanalytical monitoring of interleukin-6 levels in serum samples has emerged as a valuable tool for the early diagnosis of inflammatory diseases. Despite its advantages, there is a lack of strategies for the label-free voltammetric determination of cytokines. Here, a novel chitosan/genipin modified fluorine tin oxide electrode was developed providing an in-situ hydrogel formation (FTO/CSG). This platform was applied for the detection of interleukin-6, a major pro-inflammatory cytokine. Transmission electron microscopy (TEM), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS) indicated genipin serves as an efficient green cross-linker to build the immunosensing platform (FTO/CSG/anti-IL-6). EIS showed an increase in charge transfer resistance from 326 to 1360 kΩ after the immobilization of anti-IL-6 antibodies. By square wave voltammetry, this method achieved a detection limit of 0.03 pg mL−1 with a wide linear range of 0.05–1000 pg mL−1. Additionally, it displayed a high selectivity index when tested in the presence of three inflammatory cytokines as interfering proteins: IL-12, IL-1β, and TNF-α. The sample matrix effect showed a peak current variation lower than 5 %. The novel method was applied for the quantification of IL-6 in serum samples of septic mice. No statistical differences were observed between the standard ELISA and the proposed method using a confidence level of 95 %. •Novel green, ultrasensitive and disposable immunosensor for cytokine IL-6 detection•Modified FTO electrode based on chitosan/genipin hydrogel biofilm•Genipin was applied as a biocompatible support for antibody immobilization.•High selectivity for IL-6 determination in septic serum•Excellent accuracy of the immunosensor was obtained when compared to ELISA testing.