Near-infrared fluorescent nerve contrast agents and methods of use thereof

A method of imaging tissue or cells, the method comprising:

• (a) intravenously administering an imaging composition to an organism comprising the tissue or cells, wherein the imaging composition consists essentially of an imaging agent and wherein the intravenous administering comprises contacting the tissue or cells with the imaging agent, wherein the imaging agent is Oxazine 4 perchlorate (OX4);
• (b) irradiating the tissue or cells contacted with the imaging agent at a wavelength absorbed by the imaging agent to provide irradiated tissue or cells;
• and
• (c) detecting an optical signal from the irradiated tissue or cells, thereby imaging the tissue or cells,
• wherein the imaging agent is selectively absorbed by nerve tissue or nerve cells and the selectivity is at least 2:1 relative to muscle cells.