Plasmonic nanoparticle-assisted single-molecule dynamic binding for protein kinase activity digital counting.

In this work, we design a new approach for digital counting-based protein kinase activity assay by using plasmonic nanoparticle-assisted single-molecule dynamic binding. This method breaks the concentration-dependent limitation in single-molecule detection and displays good selectivity and sensitivity with a detection limit as low as 0.0001 U mL -1 for the protein kinase A (PKA) assay, which would find broad applications in drug screening and medical investigations.