Nitric oxide (NO), an endogenous diatomic free radical, mediates multiple physiological processes including angiogenesis, blood pressure regulation, wound healing, and the immune response. In vivo NO production is achieved by the three nitric oxide synthase (NOS) enzymes: endothelial, neuronal, and inducible NOS (eNOS, nNOS, and iNOS, respectively). The NOS enzymes generate NO at varied concentrations (nM–µM) and kinetics dependent on the enzyme location and purpose. For example, low concentrations of NO are generated from endothelial and neuronal NOS for blood vessel dilation/formation and various roles in neurotransmission. Activation of the inducible NOS isoform by immunological stimuli (e.g., lipopolysaccharides from bacteria) causes sustained NO release at high concentrations for eradicating foreign pathogens, which is central to the innate immune response. It is these critical physiological roles of endogenous NO that inspired us to design new NO-releasing macromolecular scaffolds and surfaces for use as antimicrobials and implanted device coatings. Along with this major research thrust, we also focus on developing NO-selective electrochemical sensors which are capable of measuring NO directly in complex environments (e.g., serum, wound fluid, blood).