Porous Metal–Organic Framework Nanoparticles

Metal–organic frameworks (MOFs) are hybrid crystalline particles composed of metal cations and organic linkers. Ranging from micro- to nanoscale depending on the preparation conditions, they have achieved a prevalent position among porous materials. The fact that varying either the metal cation or the organic component leads to a wide range of pore sizes and structures has made them very appealing materials in a broad variety of fields, including gas storage, heterogeneus catalysis, separation, imaging, biosensing, agriculture, and biomedicine. By optimizing the internal pore volume, many molecules of different natures can be accommodated within the matrix. For instance, the anticancer drug doxorubicin is well known to enter within iron trimesate MIL-100(Fe) nanoMOF. However, the use of this inclusion complex in biomedicine requires the controlled release of the drug. As reported in one of the articles within this Special Issue [1], this goal can be achieved either by modifying the way the drug is loaded into the MOF or by noncovalently coating the surface with appropriate biocompatible materials. Furthermore, the latter can also lead to a higher colloidal stability of the particles. The innovative use of the ssNMR technique on these inclusion complexes associated with a selective isotope labeling strategy gave the authors deeper insights into both the structure of the complexes as well as to the drug release rates and mechanism

Multivalent Lactose–Ferrocene Conjugates Based on Poly (Amido Amine) Dendrimers and Gold Nanoparticles as Electrochemical Probes for Sensing Galectin-3

Galectin-3 is considered a cancer biomarker and bioindicator of fibrosis and cardiac remodeling and, therefore, it is desirable to develop convenient methods for its detection. Herein, an approach based on the development of multivalent electrochemical probes with high galectin-3 sensing abilities is reported. The probes consist of multivalent presentations of lactose–ferrocene conjugates scaffolded on poly (amido amine) (PAMAM) dendrimers and gold nanoparticles. Such multivalent lactose–ferrocene conjugates are synthesized by coupling of azidomethyl ferrocene–lactose building blocks on alkyne-functionalized PAMAM, for the case of the glycodendrimers, and to disulfide-functionalized linkers that are then used for the surface modification of citrate-stabilized gold nanoparticles. The binding and sensing abilities toward galectin-3 of both ferrocene-containing lactose dendrimers and gold nanoparticles have been evaluated by means of isothermal titration calorimetry, UV–vis spectroscopy, and differential pulse voltammetry. The highest sensitivity by electrochemical methods to galectin-3 was shown by lactosylferrocenylated gold nanoparticles, which are able to detect the lectin in nanomolar concentrations

Design of engineered cyclodextrin derivatives for spontaneous coating of highly porous metal-organic framework nanoparticles in aqueous media

Nanosized metal-organic frameworks (nanoMOFs) MIL-100(Fe) are highly porous and biodegradable materials that have emerged as promising drug nanocarriers. A challenging issue concerns their surface functionalization in order to evade the immune system and to provide molecular recognition ability, so that they can be used for specific targeting. A convenient method for their coating with tetraethylene glycol, polyethylene glycol, and mannose residues is reported herein. The method consists of the organic solvent-free self-assembly on the nanoMOFs of building blocks based on beta-cyclodextrin facially derivatized with the referred functional moieties, and multiple phosphate groups to anchor to the nanoparticles’ surface. The coating of nanoMOFs with cyclodextrin phosphate without further functional groups led to a significant decrease of macrophage uptake, slightly improved by polyethylene glycol or mannose-containing cyclodextrin phosphate coating. More notably, nanoMOFs modified with tetraethylene glycol-containing cyclodextrin phosphate displayed the most effcient “stealth” effect. Mannose-coated nanoMOFs displayed a remarkably enhanced binding affnity towards a specific mannose receptor, such as Concanavalin A, due to the multivalent display of the monosaccharide, as well as reduced macrophage internalization. Coating with tetraethylente glycol of nanoMOFs after loading with doxorubicin is also described. Therefore, phosphorylated cyclodextrins o er a versatile platform to coat nanoMOFs in an organic solvent-free, one step manner, providing them with new biorecognition and/or “stealth” properties

Citric acid-γ-cyclodextrin crosslinked oligomers as carriers for doxorubicin delivery

International audienceTwo citric acid crosslinked γ-cyclodextrin oligomers (pγ-CyD) with a MW of 21-33 kDa and 10-15 γ-CyD units per molecule were prepared by following green chemistry methods and were fully characterized. The non-covalent association of doxorubicin (DOX) with these macromolecules was investigated in neutral aqueous medium by means of circular dichroism (CD), UV-vis absorption and fluorescence. Global analysis of multiwavelength spectroscopic CD and fluorescence titration data, taking into account the DOX monomer-dimer equilibrium, evidenced the formation of 1 : 1 and 1 : 2 pγ-CyD unit-DOX complexes. The binding constants are 1-2 orders of magnitude higher than those obtained for γ-CyD and depend on the characteristics of the oligomer batch used. The concentration profiles of the species in solution evidence the progressive monomerization of DOX with increasing oligomer concentration. Confocal fluorescence imaging and spectral imaging showed a similar drug distribution within the MCF-7 cell line incubated with either DOX complexed to pγ-CyD or free DOX. In both cases DOX is taken up into the cell nucleus without any degradation

Poly(amido amine)-Based Mannose-Glycodendrimers As Multielectron Redox Probes for Improving Lectin Sensing

An easy-to-prepare series of electroactive poly­(amido amine) (PAMAM)-based dendrimers of generations G0 to G2 having mannopyranosylferrocenyl moieties in the periphery to detect carbohydrate–protein interactions is reported. The synthesis involved the functionalization of the PAMAM surface with azidomethylferrocenyl groups and subsequent coupling of mannoside units by the Cu­(I)-catalyzed Huisgen reaction. The binding affinity of the series of electroactive glycodendrimers was studied by isothermal titration calorimetry (ITC) and differential pulse voltammetry (DPV). Upon complexation of the glycodendrimers conjugates with prototypical concanavalin A (Con A), voltammograms showed a decrease of the peak current. Such dendrimers showed a notable improvement of redox sensing abilities toward Con A when compared with mono- and divalent analogues, based on both the glycoside multivalent and ferrocene dendritic effects

One‐Step Photochemical Green Synthesis of Water‐Dispersible Ag, Au, and Au@Ag Core–Shell Nanoparticles

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Self-assembled multifunctional core–shell highly porous metal–organic framework nanoparticles

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