Sensors for real time monitoring of nitric
oxide in vivo and in vitro
This technology provides a new method for sensing nitric oxide by using single-walled carbon nanotube fluorescence.
Nitric oxide (NO) is a gaseous, free radical, which plays a role as an intracellular and intercellular messenger for signaling. Detection of small molecules has traditionally been relatively difficult, and becomes even more difficult at low concentrations. Examples of tools that may be used to detect such species include visible-fluorescence probes, chemiluminescence-based devices, and X-ray photoelectron and electron paramagnetic resonance (EPR) spectroscopy. A series of diaminofluorescins and metal–fluorophore complexes have been widely applied to detect cellular NO. However, such methods may include significant limitations. For example, diaminofluoresceins generally detect molecules indirectly. Other limitations include photobleaching and lack of optical penetration through biological tissues for metal–fluorophore complexes. The current device is used to detect and visualize NO in living cells which consists of a near-infrared (nIR) fluorescence sensor. The sensor is synthesized by combining SWNT-polymer with diaminophenyl-modified dextran (DAP-dex), resulting in a DAP dex SWNT hybrid. Biocompatible and hydrophilic dextran is functionalized by the diaminophenyl (DAP) group, and then DAP-functionalized dextran is used for suspending SWNTs individually through dialysis. After functionalization, DAP groups on SWNTs are able to selectively recognize NO. This chemical transformation on SWNTs induces the change of their nIR fluorescence, allowing selective detection and imaging of NO. A SWNT-based optical NO sensor generating nIR fluorescence has some advantages compared to organic and organometallic fluorophores, such as high resistance to photo-bleaching, no overlapping with autof1uorescence arising from endogenous fluorophores and high penetrating ability into deep tissues. Therefore, a SWNT-based optical NO sensor can be applied to real time NO detection in vivo as well as in vitro.
Enhanced tissue penetration
No overlapping with
autof1uorescence arising from endogenous fluorophores
High resistance to photo-bleaching - SWCNTs
exhibit good photo-stability
Real time NO detection in
vivo as well as in vitro