NIR-Triggered Release of Caged Nitric Oxide using Upconverting Nanostructured Materials

In this manuscript, a novel strategy for the therapeutic delivery of nitric oxide to physiological targets is described. Nitric oxide (NO) is a key vasodilator in mammalian cardiovascular systems and has been shown to sensitize tissue to γ -radiation. However, photochemical NO precursors that can be activated by these near-infrared (NIR) wavelengths are extremely limited. Herein, we have addressed this issue by utilizing the known NIR to visible upconversion properties of lanthanide cations doped NaYF 4 nanocrystals. This result is a potential game changer in multiphoton excitation based therapeutic delivery of NO and other small molecule bioregulators. The bioregulatory molecule nitric oxide (NO) plays important roles in cancer biology and has been implicated in both tumor growth and suppression. [ 1 ] Furthermore, NO is a γ -radiation sensitizer that can enhance selective killing of neoplastic tissues. For these reasons, there is considerable interest in developing methods for NO delivery to specifi c physiological targets. In this context, several laboratories have explored photoactivated NO delivery to specifi c tissues upon demand. [ 2‐7 ] A key advantage of photochemical triggering