Evaluation of Encoded Layer-By-Layer Coated Microparticles As Protease Sensors**

Proteases are important pharmaceutical targets for new drugs because of their involvement in numerous disease processes. This study evaluates whether photophysically encoded microparticles carrying fluorescently labeled protease substrates (peptides) at their surface show potential for detecting proteases in a sample. Layer-by-layer (LbL) polyelectrolyte coatings, containing a red-labeled peptidic trypsin substrate, are carefully designed and applied at the surface of the encoded microparticles. The peptide-loaded LbL coatings lose their red fluorescence upon incubation in a trypsin solution, indicating that LbL-coated microparticles show potential to screen for the presence of active proteases in biological samples.