S-Nitrosothiols (RSNOs) are related to a variety of nitric oxide (NO)-dependent physiological processes such as vasorelaxation and anti-platelet activity. Recent studies view RSNO deficiency in blood as an indicator of endothelial dysfunction associated with cardiovascular diseases. Most assay techniques for RSNOs require extensive sample preparation steps and complex measurement systems. Further, no analytical methods exist that allow direct measurement in whole blood samples. This book describes, for the first time, the development of new electrochemical sensor for real-time blood RSNO analysis by utilizing the RSNO decomposition chemistry of novel "NO generating polymers" possessing Cu(I/II) and organoselenium catalysts. The RSNO sensor approach should enable rapid and reliable estimation of RSNOs in whole blood samples and will help indicate whether RSNO levels can be clinical marker for certain diseases. The approach described should be especially useful to professionals in the bioanalytical and biomaterial fields, as well as anyone who seeks to develop biosensors by exploiting biomimetic catalysts or biocompatible polymeric interfaces for blood contacting medical devices.