An Activity-Based Nanosensor for Minimally-Invasive Measurement of Protease Activity in Traumatic Brain Injury

Current screening and diagnostic tools for traumatic brain injury (TBI) have limitations in sensitivity and prognostication. Aberrant protease activity is a central process that drives disease progression in TBI and is associated with worsened prognosis; thus direct measurements of protease activity could provide more diagnostic information. In this study, we engineered a nanosensor that releases a measurable signal into the blood and urine in response to activity from the TBI-associated protease calpain. Readouts from our nanosensor were designed to be compatible with ELISA and lateral flow assays, clinically-relevant assay modalities. In a mouse model of TBI, we demonstrated greater sensitivity of the nanosensor with the addition of targeting ligands to hyaluronic acid. In evaluation of mice with mild or severe injuries, our nanosensor identified mild TBI with a higher sensitivity than the clinical biomarker GFAP. This nanosensor technology allows for measurement of TBI-associated proteases without the need to directly access brain tissue, and has the potential to complement existing TBI diagnostic tools. ### Competing Interest Statement The authors have declared no competing interest.