Novel Strategies for Biodetection: Preliminary Application to Traumatic Brain Injury

The sensor team at the Los Alamos National Laboratory is an integrated multidisciplinary group that develops both core technologies as well as accessory tools for efficient biodetection. We have developed a waveguide-based optical biosensor for the efficient and ultra-sensitive, rapid detection of biological agents. We have previously demonstrated the use of this technology for the detection of biomarkers associated with many diseases. Herein, we present the preliminary data demonstrating the extension of this technology to the discovery and detection of Traumatic Brain Injury (TBI). TBI afflicts a significant percentage of US troops deployed in Iraq and Afghanistan, but is difficult to diagnose efficiently. Currently, only neuropsychological questionnaires are being used for the diagnosis of this condition, which can range from mild concussion to severe brain damage. The ultimate goal of this project is to develop a rapid biomarker-based diagnostic for TBI in blood. However, this cannot be accomplished until a comprehensive repertoire of biomarkers secreted during brain injury is established. This requires an integrated biomarker discovery and detection approach that is sampled directly from human serum and cerebrospinal fluid. The results reported here are preliminary steps in that direction wherein we aim to develop two different methods for the discovery of novel biomarkers of TBI in blood and cerebrospinal fluid, as well as develop assays for two biomarkers on an ultra-sensitive waveguide-based platform that was developed at LANL. We were able to evaluate two different methods for biomarker discovery: Matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) and two dimensional gel electrophoresis (2-DE) in serum samples. In addition to development of depletion protocols to remove abundant proteins in serum, we were also able to detect spiked TBI biomarkers using both methods. However, the results clearly show that for protein biomarkers, MALDI MS is much more sensitive than 2-DE. We also developed a sandwich immunoassay on a waveguide-based platform for a TBI biomarker, procalcitonin, using commercially available antibodies. We show with our methods that we were able to directly detect procalcitonin from human serum. While our discovery and detection methods show promising results, these methods need to be further optimized before we can apply it to clinically relevant samples.