Surface Modification of Gadolinium Oxide Thin Films and Nanoparticles using Poly(ethylene glycol)-Phosphate

Abstract

The performance of nanomaterials for biomedical applications is highly dependent on the nature and the quality of surface coatings. In particular, the development of functionalized nanoparticles for magnetic resonance imaging (MRI) requires the grafting of hydrophilic, nonimmunogenic, and biocompatible polymers such as poly(ethylene glycol) (PEG). Attached at the surface of nanoparticles, this polymer enhances the steric repulsion and therefore the stability of the colloids. In this study, phosphate molecules were used as an alternative to silanes or carboxylic acids, to graft PEG at the surface of ultrasmall gadolinium oxide nanoparticles (US-Gd(2)O(3), 2-3 nm diameter). This emerging, high-sensitivity "positive" contrast agent is used for signal enhancement in T(1)-weighted molecular and cellular MRI. Comparative grafting assays were performed on Gd(2)O(3) thin films, which demonstrated the strong reaction of phosphate with Gd(2)O(3) compared to silane and carboxyl groups. Therefore, PEG-phosphate was preferentially used to coat US-Gd(2)O(3) nanoparticles. The grafting of this polymer on the particles was confirmed by XPS and FTIR. These analyses also demonstrated the strong attachment of PEG-phosphate at the surface of Gd(2)O(3), forming a protective layer on the nanoparticles. The stability in aqueous solution, the relaxometric properties, and the MRI signal of PEG-phosphate-covered Gd(2)O(3) particles were also better than those from non-PEGylated nanoparticles. As a result, reacting PEG-phosphate with Gd(2)O(3) particles is a promising, rapid, one-step procedure to PEGylate US-Gd(2)O(3) nanoparticles, an emerging "positive" contrast agent for preclinical molecular and cellular applications.

Tailored biological retention and efficient clearance of pegylated ultra-small MnO nanoparticles as positive MRI contrast agents for molecular imaging

“…[51][52][53] The contribution at 531.5 eV strongly increased aer dendron graing on the MnO nanoparticles, mainly due to the contribution of P-O-Mn and MnOH ( Table 1). The contribution at 534.5 eV, associated with P-OH, decreased.…”

Gadolinium oxide: Exclusive selectivity and sensitivity in the enrichment of phosphorylated biomolecules

“…Four phosphopeptides above 3500 Da are shown as inset. Non-phosphopeptides (NPP) at 1267(YLGYLEQLLR, ␣ S1 , 106-115) and 1758 (HQGLPQEVLNENLLR, ␣ S2 , [23][24][25][26][27][28][29][30][31][32][33][34][35][36][37] are difficult to remove. They bind with Gd 2 O 3 at applied pH because of the presence of glutamic acid (E).…”

Personalized nanomedicine advancements for stem cell tracking

“…Gado CELLTrack (BioPAL)—it is expected that this approach may be further pursued [167]. Further work to optimize the surface coatings of gadolinium oxide nanoparticles is under way, with a range of modifications, such as using shells made of PEG [168] and DEG[169], silica [170], and albumins [171]. Another approach is to capture gadolinium atoms within carbon cages made of nanotubes[172] or fullerenes [173].…”