Individual Virus Detection by Peptide–Gold Nanocluster‐Assembled Artificial Binder

Ultrasensitive point‐of‐care detection is urgently required for viruses with high infectivity and lethality rates. In this study, we developed a direct detection platform, a peptide–gold nanocluster‐assembled binder (PEGNAB), in which antigen‐binding polymeric peptides are modified on a single gold nanocluster. This innovative platform has been applied to detect the influenza A virus (IAV), and it exhibits a high affinity for its spike protein, hemagglutinin, owing to its multisite binding mechanism. Approximately 500–800 PEGNAB particles were bound per virion, enabling individual virus detection through signal amplification. The linear detection range for IAV was 1–100 copies per well. A PEGNAB‐based IAV antigen assay kit and paper strip were developed, offering simple operation, cost‐effectiveness, and ultra‐high sensitivity. In a double‐blind trial involving 130 throat swabs (80 positive and 50 negative specimens), the PEGNAB kit achieved 98.8% sensitivity and 96% specificity, and the PEGNAB strip achieved 97.5% sensitivity and 96% specificity, as validated against quantitative polymerase chain reaction. The results demonstrate that different PEGNAB‐based target binding modes can be readily adapted to various pathogens by altering the peptide sequence.