Energy transfer-based biosensing of protease activity measured using an electroluminescent platform

Abstract

We present a biosensing platform that uses spatial electroluminescent (EL) illumination combined with charge-coupled device (CCD)-based detection for fluorescence measurements. The resulting EL-CCD detector platform was used to monitor different protease activities with substrates labeled for fluorescence resonance energy transfer (FRET)-based assays. The first uses a commercial FITC/DABCYL-SNAP-25 peptide substrate to monitor the activity of the light chain derivative (LcA) of botulinum neurotoxin A, achieving a limit of detection (LOD) of 1.25 nM (62 ng/ml). The second protease activity assay measured trypsin proteolysis using peptide substrates immobilized onto semiconductor quantum dot (QD) nanoparticles with a LOD of 6.2 nM trypsin (140 ng/ml). The specific ovomucoid inhibition of trypsin activity was also monitored. The highlighted studies clearly demonstrate the utility of the EL-CCD detector platform for monitoring fluorescent-based protease activity assays with potential healthcare applications, including point-of-care diagnostics.