Antifouling peptides engineered with amino-terminal copper-nickel-binding motifs for low-fouling and antibacterial electrochemical detection of HER2 in complex biofluids.

Conventional electrochemical biosensors used for biomarker detection in complex biofluids often suffer from reduced sensitivity and accuracy due to nonspecific molecular adsorption and bacterial interference. To overcome these limitations, it is essential to design biosensors that combine antifouling and antibacterial functionalities. Herein, a multifunctional branched peptide (MBP) was designed and used to construct electrochemical biosensor for human epidermal growth factor receptor 2 (HER2) detection in complex biofluids. The designed MBP features an antifouling backbone and two functional branches: amino-terminal copper-nickel-binding (ATCUN) motif that exhibits antibacterial activity through copper ion coordination, and a recognition sequence for specific capture of HER2. The developed biosensor based on MBP not only demonstrated outstanding antifouling and antibacterial performance, as confirmed through comprehensive characterization including electrochemical analysis, fluorescence imaging and plate counting, but exhibited high sensitivity for HER2 detection with a low detection limit of 0.14 pg mL-1. Notably, the HER2 detection results obtained from the MBP-based biosensor showed excellent agreement with commercial enzyme-linked immunosorbent assays (ELISA) kits across multiple clinical samples, indicating substantial clinical utility. This work presents an innovative strategy for designing multifunctional peptides that facilitate the development of antifouling and antibacterial sensing platforms capable of accurate biomarker quantification in challenging biological media.