PEGylation of Nanosubstrates
(Titania) with Multifunctional
Reagents: At the Crossroads between Nanoparticles and Nanocomposites
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Abstract
Titania (anatase) nanoparticles were successfully PEGylated
through
the use of catechol (dopamine)-terminated PEG derivatives. The resulting
materials were characterized by excellent stability at neutral pH
and extremely low toxicity (phagocytic and nonphagocytic cell lines).
In
particular, we focused on the comparison between mono- and bis-catechol
PEGs. Due to the double terminal anchorage on the titania surface,
bis-catechol ligands can produce chains differing from classical monoanchored
PEG in conformation (horseshoe-shaped vs brush) and thus the possibility
of interactions with biomolecules. At the same time, less than quantitative
catechol binding may lead to the presence of dangling chains with
unbound catechols which can polymerize and eventually produce PEG/titania
nanocomposite colloids. Our results on double-functional PEG2000 show
the latter to be the case. Pluronic F127 was also used as a bifunctional
ligand, leading to nanocomposite aggregates with an even larger organic
content