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.