PAMAM dendrimers functionalized with ruthenium nitrosyl as nitric oxide carriers

The functionalization of three generations of polyamidoamine (PAMAM G0, G2 and G3) dendrimers with the NO-donor trans-[Ru(NO)(NH3)(4)(ina)](BF4)(3) (ina = isonicotinic acid) is reported. PAMAMs were modified through a peptide-type bond between the carboxyl group of the ina ligand and the dendrimer superficial amines. Compounds were characterized by FT-IR, UV-Vis, CV, DPV, H-1 NMR, ICP-OES, and the structure of the complextrans-[Ru(NO)(NH3)(4)(ina)](BF4)(SiF6)center dot H2O was determined by single crystal X-Ray analysis. The experimental data indicated the immobilization of 4, similar to 8 and similar to 27 nitrosyl complexes on the G0, G2 and G3 dendrimer's surface, respectively, which corresponds to similar to 1.0-1.43 mu mol NO per mg of dendrimer. FT-IR, UV-Vis and electrochemical assays suggest that the functionalization of PAMAM did not alter the coordination sphere of the ruthenium nitrosyl complex neither the formal reduction potential of (RuNO+)-N-II/(RuNO0)-N-II couple regarding to the complex not attached to PAMAM. The NO release in these compounds, through light irradiation (lambda = 355 nm) and one-electron reduction (Eu2+), was investigated. (C) 2013 Elsevier B. V. All rights reserved.