The Cullen Laboratory
Neural Engineering in Neurotrauma

Blast-Induced Traumatic Brain Injury

Blast exposure is a 21st century reality in counter-insurgency warfare. The high incidence of closed head non-impact blast-induced traumatic brain injury (bTBI) in warfighters serving in Iraq and Afghanistan suggests a direct mechanism by which blast exposure detrimentally affects the brain. However, potentially unique injury mechanisms and exposure thresholds for bTBI remain unknown. The Cullen Lab is working to identify acute biophysical responses of neural cells occurring directly due to blast wave propagation through the brain. Relating these patterns of sub-cellular damage to both the predicted micro-injury biomechanics and later, evolving neuropathology may permit establishment of a “signature” of bTBI.

Neural Cellular Biophysical Responses to Blast Exposure

caption: Blast-induced cellular damage (yellow) in the rat hippocampus

Movie

Damaged neurons (green) in the rat cortex following blast

caption: Degenerating neurons in the rat cortex following blast

Colorimetric Materials-Based Dosimetry Using Photonic Nanocrystals

To compliment these efforts, we have developed a novel materials-based blast injury dosimeter using photonic crystalline nanostructures that change color specifically following blast exposure. Appearing as an array of small colored stickers, these nanostructures may be affixed to uniforms and helmets to report blast exposure sufficient to induce even subtle neuropathology. Our current efforts focus on calibrating the degree of color change and/or color loss with blast levels inducing brain injury across a range of severities. This technology offers a lightweight, power-free sensor that can be readily interpreted by the naked eye, thus serving as an experimental tool as well as a diagnostics marker to improve bTBI outcomes in our warfighters. Collectively, our efforts to elucidate the causative mechanism(s) and potentially unique neuropathology of bTBI in parallel with blast dosimetry help establish exposure tolerances and facilitate the development of treatments to halt progressive neural damage and/or degeneration.

BID concept and function

(A) BID arrays may be affixed to warfighter uniforms in multiple locations. These arrays consist of multiple engineered photonic crystalline microstructures, the colorimetric properties of which are a result of the nano-scale structure, creating so-called “structural color”. (B) We have previously demonstrated that blast exposure precisely disrupts the structure at the nano- and micro-scales, creating color change and loss, respectively (color change/loss scale bar: 1 mm; SEM scale bar: 500 nm). These properties make our photonic crystalline arrays ideal to serve as a colorimetric blast injury dosimeter.