Control of the PEO Chain Conformation on Nanoparticles by Adsorption of PEO-block-Poly(l-lysine) Copolymers and Its Significance on Colloidal Stability and Protein Repellency

Abstract

The physical adsorption of PEO(n)-b-PLL(m) copolymers onto silica nanoparticles and the related properties of poly(ethylene oxide) (PEO)-coated particles were studied as a function of the block copolymer composition. Copolymers adopt an anchor-buoy conformation at the particle surface owing to a preferential affinity of poly(L-lysine) (PLL) blocks with the silica surface over PEO blocks when a large excess of copolymer is used. The interdistance between PEO chains at particle surface is highly dependent on the size of PLL segments; a dense brush of PEO is obtained for short PLL blocks (DP = 10), whereas PEO chains adopt a so-called interacting "mushroom" conformation for large PLL blocks (DP = 270). The size of the PEO blocks does not really influence the copolymer surface density, but it has a strong effect on the PEO layer thickness as expected. Salt and protein stability studies led to similar conclusions about the effectiveness of a PEO layer with a dense brush conformation to prevent colloidal aggregation and protein adsorption. Besides, a minimal PEO length is required to get full stabilization properties; as a matter of fact, both PEO(45)-b-PLL(10) and PEO(113)-b-PLL(10) give rise to a PEO brush conformation but only the latter copolymer efficiently stabilizes the particles in the presence of salt or proteins.

Nanoparticle stability in biologically relevant media: influence of polymer architecture

“…It can be deduced by comparing the Flory radius (R F ) of surface chains, 5,7 to either the distance between PEG grafting points (D), or the thickness of the PEG layer (L). It can be deduced by comparing the Flory radius (R F ) of surface chains, 5,7 to either the distance between PEG grafting points (D), or the thickness of the PEG layer (L).…”

“…3, bottom row). 5,7,52 As all nanoparticles are nearly electrostatically neutral under the conditions used for ITC, the enthalpic driving force is attributed to a combination of weak non-covalent forces such hydrogen bonding and/or van der Waals interactions, rather than electrostatic effects. Human serum albumin (HSA) is the most abundant protein in plasma, known for its extraordinary ligand-binding capacity, its capability as a biomarker, and used clinically to treat a number of diseases.…”

“…[5][6][7][8] It is generally agreed that high molecular weight PEG (42000 Da) will endow nanoparticles with stealth properties, 9 and that higher PEG surface density will reduce protein binding and macrophage uptake, hence prolonging circulation half-lives. [5][6][7][8] It is generally agreed that high molecular weight PEG (42000 Da) will endow nanoparticles with stealth properties, 9 and that higher PEG surface density will reduce protein binding and macrophage uptake, hence prolonging circulation half-lives.…”

A method to Quantify the Affinity of Cabazitaxel for PLA-PEG Nanoparticles and Investigate the Influence of the Nano-Assembly Structure on the Drug/Particle Association

“…The corresponding distance between two PEG 5000 chains was d PEG =2.6 nm. The PEG chains conformation can be deduced by comparing the distance d PEG to the Flory radius of PEG in good solvent (R F = 6.1 nm), as already done by Louguet et al (30). The distance d PEG being smaller than R F , suggests that the PEG chains strongly interact with each other and were forced to stretch away from the surface of micelle adopting a brush conformation.…”

The role of PEG conformation in mixed layers: from protein corona substrate to steric stabilization avoiding protein adsorption

“…It has been demonstrated that a stretching of a polymeric chain produce a blue shift of the SPR, due to the decrease of ligand density in the vicinity of the AuNP [37]. It is also known that a high density of SH-PEG grafted on the AuNPs surface lead to a change of conformation from mushroom to brush [36,38,39]. Thus, the observed blue shift is likely to be caused by a stretching of the SH-PEG chains, induced at high grafting densities of SH-PEG.…”