A superior anti-fouling electrode sensing layer based on a tannic acid-polyethyleneimine-graphene oxide nanocomposite for thrombin detection in complex biological fluids

Affinity-peptide-based electrochemical sensors have emerged as promising alternatives to conventional methods because of their superior stability, chemical adaptability, and selectivity. However, their rapid loss of sensitivity caused by inactivation of the electrode surface and biological fouling has hindered their further development. To address this issue, we fabricated a sensitive and selective bifunctional peptide-based electrochemical sensor that enables thrombin detection in complex biological fluids. To achieve this, we incorporated a nanohybrid hydrogel composed of cross-linked polyphenol (tannic acid, TA) and polyamine (polyethyleneimine, PEI) co-deposition systems containing a nanomaterial (graphene oxide, GO) into the biosensor as an anti-fouling layer. The TAPEI -GO nanohybrid hydrogel enhanced the electron transfer process and selectivity of the biosensor, while preventing the adsorption of non-specific biomolecules. As a result, the stability of the electrode surface was improved, and functionalization of the active sites for engineered peptides was achieved in a highly oriented manner. The stability, simplicity, and ease of preparation of this nanohybrid hydrogel render it a suitable candidate for the fabrication of electrochemical biosensors that can function in complex biological fluids. The developed biosensor has the potential to facilitate the diagnosis and prognosis of coagulation disorder-related diseases, which would have a positive effect on public health.