0000000000069649
AUTHOR
José Avila
GraftFast Surface Engineering to Improve MOF Nanoparticles Furtiveness
International audience; Controlling the outer surface of nanometric metal–organic frameworks (nanoMOFs) and further understanding the in vivo effect of the coated material are crucial for the convenient biomedical applications of MOFs. However, in most studies, the surface modification protocol is often associated with significant toxicity and/or lack of selectivity. As an alternative, how the highly selective and general grafting GraftFast method leads, through a green and simple process, to the successful attachment of multifunctional biopolymers (polyethylene glycol (PEG) and hyaluronic acid) on the external surface of nanoMOFs is reported. In particular, effectively PEGylated iron trime…
Chitosan-coated mesoporous MIL-100(Fe) nanoparticles as improved bio-compatible oral nanocarriers
Nanometric biocompatible Metal-Organic Frameworks (nanoMOFs) are promising candidates for drug delivery. Up to now, most studies have targeted the intravenous route, related to pain and severe complications; whereas nanoMOFs for oral administration, a commonly used non-invasive and simpler route, remains however unexplored. We propose here the biofriendly preparation of a suitable oral nanocarrier based on the benchmarked biocompatible mesoporous iron(III) trimesate nanoparticles coated with the bioadhesive polysaccharide chitosan (CS). This method does not hamper the textural/structural properties and the sorption/release abilities of the nanoMOFs upon surface engineering. The interaction …
Orbital origin and matrix element effects in the Ag/Si(111)-()R30° Fermi surface
The Fermi surface (FS) of the Ag/Si(1 1 1)-3×3 reconstruction with an excess of Ag has been mapped by angle resolved photoemission spectroscopy with polarized light in a wide region of the reciprocal space and with different detection geometries. In contrast to previous results, a strong polarization dependence is observed. Applying the dipole selection rules, it is found that the surface state at the Fermi level, S1 state, has odd symmetry with respect to the mirror plane of the honeycomb-chained triangle structure, indicating that it is mainly derived from Ag 5px and 5py orbitals. This conclusion is revised in the new frame of a inequivalent-triangle structure for the Ag/Si(1 1 1)-3×3 at …
Metal-Organic Framework Surface Functionalization: GraftFast Surface Engineering to Improve MOF Nanoparticles Furtiveness (Small 40/2018)
International audience
Quantum-well states in ultrathin Ag(111) films deposited onto H-passivated Si(111)-(1x1) surfaces
Ag(111) films were deposited at room temperature onto H-passivated Si(111)-(1x1) substrates, and subsequently annealed at 300 C. An abrupt non-reactive Ag/Si interface is formed, and very uniform non-strained Ag(111) films of 6-12 monolayers have been grown. Angle resolved photoemission spectroscopy has been used to study the valence band electronic properties of these films. Well-defined Ag sp quantum-well states (QWS) have been observed at discrete energies between 0.5-2eV below the Fermi level, and their dispersions have been measured along the GammaK, GammaMM'and GammaL symmetry directions. QWS show a parabolic bidimensional dispersion, with in-plane effective mass of 0.38-0.50mo, along…
Photoelectron lifetime determination of Ag(1 1 1) films at the Fermi surface
The electronic properties of 10 monolayers Ag(111) films deposited onto Si(111)-7 x 7 substrates at room temperature have been studied by scanning the photoelectron intensity at the Fermi level in different symmetry directions. The main features observed in these profiles correspond to Lorentzian-like peaks produced by the pass of the sp band through the Fermi level. A simple model has been developed, which connects the photoemission peak linewidth with the lifetime of photoelectrons excited from the Fermi level. The obtained inverse photoelectron lifetime values have been found to be in excellent agreement with the typical values of the Ag single crystals. These results support the fact th…
Buildup and structure of theInSe∕Ptinterface studied by angle-resolved photoemission and x-ray absorption spectroscopy
The atomic structure and the electronic nature of the $\mathrm{In}\mathrm{Se}∕\mathrm{Pt}$ interface have been studied by x-ray absorption spectroscopy and angle-resolved photoemission, respectively. By these measurements, it has been found that Pt atoms equally incorporate into two trigonal-prismatic intralayer positions existing within the InSe layer, although, at low Pt coverage, Pt atoms seem to prefer one of these sites, where they have a lower interaction with Se atoms. The atomic structure of the $\mathrm{In}\mathrm{Se}∕\mathrm{Pt}$ interface appears to determine its electronic behavior as Pt deposition increases. At initial stages of Pt diffusion, isolated Pt atoms act as a surface …