Fig. 1. EPR spectroscopy of aqueous solutions (20 mM PBS buffer containing 20% DMSO, pH 7.4) for (a) PTIO, (b) oNBN with PTIO, (c) pNBN with PTIO, and (d) BN with PTIO before (black lines) and after (red lines) UV 365 nm irradiation (4 mW cm^–2) for 20 min. In all cases, the concentrations of PTIO and NO-releasing monomers were 20 μM. (e and f) NO release profiles of the oNBN monomer (40 μM) in an aqueous medium (20 mM PBS buffer containing 5% DMSO) under (e) continuous (mean ± s.d.; n = 3) or (f) intermittent (the cyan areas indicate the light on) UV 365 nm irradiation (4 mW cm^–2).