Nitric Oxide Synthase Encapsulation in Liposomes: A Potential Delivery Platform to (Nitric Oxide)-Deficient Targets

Nitric oxide (NO) is a freely diffusible, gaseous free radical, associated with many physiological and pathological processes: such as neuronal signaling, immune response and inflammatory response. In mammalian organisms, NO is produced from L-arginine in an NADPH-dependent reaction catalyzed by a family of nitric oxide synthase (NOS) enzymes. Typically, large NO fluctuations in biological systems under/over a critical limit is associated with problems that range from transient dysfunctions to severe chronic disease states. In this regard, we explore the development of a potential delivery and release method of nitric oxide to NO-deficient sites using liposomes as vehicles. Liposomes have already been used as effective nano-carriers. In this short communication, we report on the preparation and characterization of liposomes carrying a recombinant NOS enzyme. We report on the efficacy of using liposomes to carry NOS enzymes, and on the extent of preservation of native NOS structure and function. In addition to the characterization of liposome stability and recovery of enzymatic activity after encapsulation in liposomes, we also measured the NO production upon NOS stimulation. The NO release was monitored with a nitric oxide ultrasensitive electrochemical microsensor placed near NOS-carrying liposomes. This method of NOS-carrying liposomes shows the promise of potential development as a platform for targeted NO-delivery. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.