Impact of surface curvature, grafting density and solvent type on the PEGylation of titanium dioxide nanoparticles

Abstract

a b s t r a c t TiO 2 nanoparticles (NPs) are attracting materials for biomedical applications, provided that they are coated with polymers to improve solubility, dispersion and biocompatibility. Conformation, coverage density and solvent effects largely influence their functionality and stability. In this work, we use atomistic molecular dynamics simulations to study polyethylene glycol (PEG) grafting to highly curved TiO 2 NPs (2-3 nm) in different solvents. We compare the coating polymer conformations on NPs with those on (1 0 1) flat surfaces. In water, the transition from mushroom to brush conformation starts only at high density (r = 2.25 chains/nm 2 ). In dichloromethane (DCM), at low-medium coverage (r < 1.35 chains/ nm 2 ), several interactions between the PEG chains backbone and undercoordinated Ti atoms are established, whereas at r = 2.25 chains/nm 2 the conformation clearly becomes brush-like. Finally, we demonstrate that these spherical brushes, when immersed in water, but not in DCM, follow the Daoud-Cotton (DC) classical scaling model for the polymer volume fraction dependence with the distance from the center of star-shaped systems.

Thermoresponsive Nanoparticles with Cyclic-Polymer-Grafted Shells Are More Stable than with Linear-Polymer-Grafted Shells: Effect of Polymer Topology, Molecular Weight, and Core Size

“…These parameters include the concentration, 8 the end group, 9 the monomer composition, 10 the ionic strength and type of the aqueous surrounding, 8 and, as recently demonstrated, the local monomer concentration determined by the polymer shell morphology, 8 , 11 which also is influenced by the nanoparticle curvature. 12 , 13 …”

Designing high‐performance colour cosmetics through optimization of powder flow characteristics

“… evaluated the flow behaviour of titanium dioxide dispersions in the presence of 2‐hydroxyethyl cellulose (HEC), where they found that maximum yield stress decreased when the HEC concentration increased. According to Selli et al , coated TiO 2 nanoparticles with polymer improve the solubility, dispersion and biocompatibility.…”

Dopamine-Decorated TiO2 Nanoparticles in Water: A QM/MM vs an MM Description

“…The atomic coordinates of the Ti and O atoms in the nanoparticle, as obtained by simulated annealing at 300 K and full atomic relaxation with the DFTB method in ref ( 14 ) when 46 dopamine molecules are attached, were kept fixed during all classical MM-MD simulations by Cartesian restraints with force constant equal to 5000 kcal/mol/Å 2 , the same protocol used in refs ( 57 ) and ( 58 ). This DFTB-optimized structure was solvated with a pre-equilibrated simulation box containing 6386 qSPC/Fw 55 water molecules using the LEaP module.…”