Biomarker research is of great interest in the field of traumatic brain injury (TBI), since there are numerous potential markers that may indicate central nervous system damage, yet the brain is normally well isolated and discovery is at its infancy. Traditional methods for biomarker discovery include time consuming multi step chromatographic mass spectrometery (MS) techniques or pre-defined serial probing using traditional assays, making the identification of biomarker panels limiting and expensive. In addition to the difficulty in identifying new biomarkers, clinical and animal studies contribute to added complexity. These shortfalls have motivated the development of a MS based probe that can be embedded into 3D neural cultures and obtain temporal and spatial information about the release of biomarkers.

This thesis presents the development and testing of a novel method to monitor chemical markers within a porous matrix. Using the high sensitivity MS ionization method of nano-electrospray ionization (nano-ESI) with an in-line microdialysis (MD) unit allows us to use MS to analyze low concentrations of TBI biomarkers from within cell cultures with no need for off-line sample manipulation.

The MD unit was examined both theoretically and experimentally, and a set of design variables were chosen to allow for continuous sampling and MS analysis directly from cell cultures. A model cell culture injury chamber was developed and also examined theoretically and experimentally. The chambers were constructed and filled with a porous matrix, and biologically relevant markers were locally injected into the chamber. The probe collected samples from within the matrix, which were analyzed in-line with the MD-nano-ESI MS probe. A model predicting the transport of the chemical markers within a porous matrix provided a basic understanding of what to expect experimentally. Experiments demonstrated the probe’s capability to detect chemical markers within a simple agarose matrix and a biologically complex matrix of Matrigel. In addition, cells experienced no adverse effects when cultured in chambers with the sampling probe. Samples were successfully collected through the probe in live neural cultures. Results demonstrated that this novel method of detecting biological samples using MS could potentially allow researchers to better understand the pathophysiological events of TBI.