Surface-controlled dissolution rates: a case study of nanoceria in carboxylic acid solutions

Abstract

Nanoparticle dissolution in local milieu can affect their ecotoxicity and therapeutic applications. For example, carboxylic acid release from plant roots can solubilize nanoceria in the rhizosphere, affecting cerium uptake in plants. Nanoparticle dispersions were dialyzed against ten carboxylic acid solutions for up to 30 weeks; the membrane passed cerium-ligand complexes but not nanoceria. Dispersion and solution samples were analyzed for cerium by inductively coupled plasma mass spectrometry (ICP-MS). Particle size and shape distributions were measured by transmission electron microscopy (TEM). Nanoceria dissolved in all carboxylic acid solutions, leading to cascades of progressively smaller nanoparticles and producing soluble products. The dissolution rate was proportional to nanoparticle surface area. Values of the apparent dissolution rate coefficients varied with the ligand. Both nanoceria size and shape distributions were altered by the dissolution process. Density functional theory (DFT) estimates for some possible Ce(IV) products showed that their dissolution was thermodynamically favored. However, dissolution rate coefficients did not generally correlate with energy of formation values. The surface-controlled dissolution model provides a quantitative measure for nanoparticle dissolution rates: further studies of dissolution cascades should lead to improved understanding of mechanisms and processes at nanoparticle surfaces.

The preparation temperature influences the physicochemical nature and activity of nanoceria

“…The cerium concentration in the bath of the dialysis system that contained solvothermally synthesized nanoceria in the cassette increased over time, indicating nanoceria dissolution. Citric and lactic acid increased the dissolution rate (Table 2), as previously reported [39,40]. The rate of NM-212 dissolution was much slower (Figure 8 and Table 2).…”

“…The cassette contained 500 μg cerium (as solvothermally synthesized nanoceria in 1 mL). In an initial experiment, samples were withdrawn from duplicate cassettes five times from 1344 to 4704 h. The cerium concentration in the cassettes decreased much faster at pH 4.5 than at pH 7.4, consistent with prior results [39,40]. The experiment was repeated with additional duplicate systems containing no LN resin at pH 4.5 and no HTP at pH 7.4.…”

“…The dialysis system has been described [39,40]. Nanoceria (500 μg cerium as nanoceria in 1 mL) was loaded into Slide-A-Lyzer TM dialysis cassettes with 2 kD MWCO regenerated cellulose membranes (66203) immersed in a 200 mL bath at pH 4.5 made iso-osmotic with sodium nitrate.…”

“…Dissolution was determined from the bath cerium concentration measured weekly for 2688 h (16 weeks). Citric and lactic acids (110 mM in the baths), previously shown to accelerate nanoceria dissolution [39,40], were studied. All conditions were studied in duplicate.…”

On the synthesis of bi-magnetic manganese ferrite-based core–shell nanoparticles

“…Some authors have reported the observation of dissolution phenomena on colloidal dispersions of nanoparticles subjected to thermal treatments. 10,[70][71][72][73][74][75] However, in the case of core-shell nanoparticles, the dependence of the dissolution phenomena on the size and the chemical nature of the shell has not been treated so far. Here, the systematic study revealed that manganese dissolution is more evident with shells formed by iron oxide rather than cobalt ferrite.…”