Photorelease of nitric oxide from Pluronic F127/chitosan hydrogels incorporating a water soluble ruthenium nitrosyl complex

Abstract

In this paper, the NO donor trans-(Cl,Cl)-[Ru(FT)Cl₂(NO)]Cl (Ru–NO) was incorporated in a Pluronic F127 (PL)–chitosan (CS) biocompatible hydrogel. Two concentrations were achieved (520 and 13 μg g⁻¹), resulting in hydrogels with sol–gel transition temperatures of around 36–38 °C, according to rheological studies. The presence of the Ru–NO complex did not significantly modify the thermal (DSC) and morphological (AFM) characteristics of the gels. For Ru–NO-embedded hydrogels, nitric oxide photorelease was evidenced at 400 nm. The quantum yield of photorelease was independent of the temperature at which the gel was maintained (25, 31, or 37 °C) and was found to be ca. 0.015. EPR as well as measurements using an electrochemical NO sensor also confirmed NO release upon light irradiation at 400 nm.