1 research outputs found
Potential Toxicity of Up-Converting Nanoparticles Encapsulated with a Bilayer Formed by Ligand Attraction
The
cellular toxicity of nanoparticles that were capped with a
bilayered ligand was studied using an up-converting (UC) phosphor
material as a representative nanoparticle (NP). The results indicate
that although UC NPs are known to be nontoxic, the toxicity of the
NPs depends strongly on ligand coordination conditions, in addition
to the other commonly known parameters such as size, structure, surface
charge etc. Oleate-capped hydrophobic NaYF<sub>4</sub>:Yb,Er NPs were
surface modified to yield three extreme conditions: bare particles
that were stripped of the oleate ligands; particles with covalently
bound poly(ethylene glycol) (PEG) ligands; and particles with an bilayer
of PEG-oleate ligands using the oleate surface group that was remained
after synthesis. It was found that the bare particles and the covalent
PEG NPs induced little toxicity. However, particles that were rendered
biocompatible by forming a bilayer with an amphiphilic ligand (i.e.,
PEG-oleate) resulted in significant cell toxicity. These findings
strongly suggest that the PEG-oleate group dissociated from the bilayered
oleate-capped NPs, resulting in significant toxicity by exposing the
hydrophobic oleate-capped NPs to the cell. Based on results with bare
particles, the NaLnF<sub>4</sub>:Yb,Er (Ln = Y, Gd) up-converting
phosphors are essentially less-toxic. Capping and functionalizing
these particles with ligand intercalation may, however, not be a suitable
method for rendering the NPs suitable for bioapplication as the ligand
can potentially dissociate upon cellular interaction, leading to significant
toxicity