Understanding the Colloidal Stability of the Mesoporous MIL-100(Fe) Nanoparticles in Physiological Media

Abstract

The colloidal and chemical stability of nanoparticles of the nontoxic and biodegradable iron(III) trimesate MIL-100(Fe) nanocarrier have been evaluated in the presence of a series of simulated physiological fluids for intravenous and oral administration. MIL-100(Fe) nanoparticles exhibit an appropriate colloidal stability and biodegradability, mainly dependent on both the nature of their physicochemical surface and the media composition, being a priori compatible with their biomedical use.

Chitosan-coated mesoporous MIL-100(Fe) nanoparticles as improved bio-compatible oral nanocarriers

“…The lower stability exhibited in DMEM is related with the higher concentration of phosphate, bicarbonate and pyruvate salts, which are able to strongly bind iron and may lead to a faster degradation. Remarkably, an enhanced stability conferred by the CS coating was observed in PBS (containing a higher phosphate concentration), in which uncoated MIL-100(Fe) NPs were rapidly degraded up to 30%, whereas the CS_MIL-100(Fe) NPs led to only 7% of BTC release33. Such a stabilization of the CS-coated MIL-100(Fe) NPs could tentatively be assigned to a slower diffusion of the phosphates through the CS layer, which would hamper the exchange with the carboxylate ligands.…”

Heparin‐Engineered Mesoporous Iron Metal‐Organic Framework Nanoparticles: Toward Stealth Drug Nanocarriers

“…Their ζ -potential is typically positive (+19.1 ± 4.0 mV), assigned to a higher presence of partially coordinated trimesic linker on the NP external surface, whose carboxylic groups are still protonated in water. [ 37 ] As a reminder, the KF treatment induces a replacement of the partially coordinated linkers by F anions, [ 37,38 ] as well as a notable enhancement of the colloidal stability. [ 37 ] After coating the nonKF-treated NPs with heparin, a signifi cant shift of the ζ -potential toward negative values is observed (-20.7 ± 5.0 mV), in agreement with the presence of heparin covering the external surface of the NPs.…”

“…[ 37 ] As a reminder, the KF treatment induces a replacement of the partially coordinated linkers by F anions, [ 37,38 ] as well as a notable enhancement of the colloidal stability. [ 37 ] After coating the nonKF-treated NPs with heparin, a signifi cant shift of the ζ -potential toward negative values is observed (-20.7 ± 5.0 mV), in agreement with the presence of heparin covering the external surface of the NPs. Noteworthy, the possibility of coating similar heparin amounts on either negatively or positively charged NPs tentatively suggests the participation of a combination of not only electrostatic interactions but also coordination to the CUS sites, van der Waals interactions or hydrogen bonding, as driving forces for the interaction of MIL-100(Fe) NPs with heparin molecules.…”

“…The pH might also play an important role, being several units above the pKa of the carboxylic functions (pH = 7.4 in PBS, respectively, vs pKa ≈4) as well as the chemistry of iron itself (see Pourbaix diagram), [ 47 ] the precipitation of iron hydroxides at such pH being the most thermodynamical state. [ 37 ] …”

“…The stability of the unmodifi ed MIL-100(Fe) NPs has previously been described in a recent publication. [ 37 ] Initially, the colloidal stability against salt induced aggregation was examined in water or PBS (at 37 °C) ( Figure S9, Supporting Information). The role of proteins on the colloidal stability was evaluated in a more complex media, namely, PBS supplemented with albumin (Alb), the most abundant plasma protein in mammals, and cell culture medium RPMI (Table 1 and Figure S10, Supporting Information).…”