Victoria Blue B Acts as a Protein Isomerization Targeting Probe for Monitoring Lysozyme Fibrillation

•VBB can serve as a new protein isomerization targeting (PIT) dye for detection of lysozyme fibrillation.•VBB emits near-infrared fluorescence upon recognizing lysozyme fibers but does not fluoresce when meeting native counterpart.•The VBB-based sensing system works fairly well in the presence of serum or cell extract.•The possible protein fibril-binding and fluorescence mechanism of VBB and its derivatives were discussed.•VBB is a metal ion interference-resistant probe.