Antifouling Electrochemical Biosensor Based on Liquid Metal-Incorporated Hydrogel and Multifunctional Peptide for Robust Interleukin-1β Sensing in Saliva

Abstract Enhancing the practical applicability of electrochemical biosensors in complex biological fluids hinges on addressing biofouling. Antifouling hydrogels, while effective at resisting nonspecific biomolecule adsorption, are intrinsically insulating, which poses a challenge in reconciling their antifouling capability with the need for high-sensitivity detection. To address these challenges, we developed a multifunctional hydrogel. During ultrasonication, cellulose nanocrystal (CNC) stabilized liquid metal (LM) droplets generated free radicals that initiated acrylamide (AM) polymerization to form polyacrylamide (PAM) and crosslinked with chitosan (CS), yielding the LM@CNC-PAM-CS hydrogel without external initiators or crosslinkers. This hydrogel was then combined with a multifunctional peptide (Pep) featuring antifouling and recognition functions to construct an antifouling biosensor for IL-1β detection. Electrochemical characterization and fluorescence imaging confirmed that the synergistic antifouling interface enhanced nonspecific adsorption resistance, improving biosensor stability and accuracy. The sensor detected IL-1β over 1 pg mL−1 −1 μg mL−1 with a limit of detection (LOD) of 0.34 pg mL−1, and correlated well with enzyme-linked immunosorbent assay (ELISA) in real human saliva samples. Thus, this design offers a viable strategy for clinical diagnostics in real samples with antifouling electrochemical biosensors.