Sensitive protein detection and visualization using protein-binding peptides

Silk sericin (SS) as a silk protein has important applications in biomedical and textile fields, and thus finding a facile method for detecting and imaging it is very important. Here, we show that a free SS-binding peptide, labeled with horseradish peroxidase and fluorescein isothiocyanate, could be used as a probe to determine the concentration of SS (from 1 to 100 μg/ml) in a dilute solution with a detection limit of 0.073 μg/ml and visualize the distribution of SS on a substrate under a fluorescent microscope, respectively. This work highlights the importance in discovering a protein-binding peptide and the power of such a peptide for the detection and imaging of technologically important proteins.