1 research outputs found
EPR Characterization of Copper(II) Complexes of PAMAM-Py Dendrimers for Biocatalysis in the Absence and Presence of Reducing Agents and a Spin Trap
Polyamidoamine (PAMAM)
dendrimers at different generations (from
G2 to G6) were functionalized with pyridine (Py) groups at the external
surface, and their complexation behavior with CuÂ(II) at increasing
molar ratios between the ions and the Py groups was analyzed in the
absence and presence of reducing agents and a spin trap. These CuÂ(II)–dendrimer
complexes may be used as antitumor and antiamyloidogenesis drugs,
similarly to other CuÂ(II)–dendrimer complexes, and as biocatalysts.
Indeed, they have revealed to selectively catalyze molecular oxygen
reduction to generate reactive oxygen species (ROS). A computer-aided
electron paramagnetic resonance (EPR) study of these complexes allowed
us to identify different complexes by increasing the CuÂ(II)/Py molar
ratio for the different generations. Binuclear EPR-silent complexes
were formed at the highest generations. The differently complexed
CuÂ(II) ions showed a different capability to be reduced, starting
from the most exposed at the dendrimer surface bearing a stable CuÂ(II)–Py<sub>2</sub> coordination. CuÂ(II)–G5 showed peculiar structural
properties which probably favored its activity as biocatalyst. The
spin trap was able to capture hydroxyl radicals, which became clearly
EPR visible after all CuÂ(II) ions were reduced to CuÂ(I). This method
may be used as a platform to study interactions of CuÂ(II) in nanosized
macromolecules for biomedical purposes, mainly in biocatalysis involving
redox reactions and formation of ROS