Abstract: The present invention relates to devices and methods of use thereof for detection of biomolecules, in vitro, in vivo, or in situ. The invention relates to methods of diagnosing and/or treating a subject as having or being at risk of developing a disease or condition that is associated with abnormal levels of one or more biomolecules including, but not limited to, inter alia, epilepsy, diseases of the basal ganglia, athetoid, dystonic diseases, neoplasms, Parkinson's disease, brain injuries, spinal cord injuries, and cancer. The invention also provides methods of differentiating white matter from gray matter. In some embodiments, regions of the brain to be resected or targeted for pharmaceutical therapy are identified using sensors. The invention further provides methods of measuring the neurotoxicity of a material by comparing microvoltammograms of a neural tissue in the presence and absence of the material using the inventive sensors.