Nanoscale metal-organic frameworks for the delivery of nucleic acids to cancer cells.

Therapeutic nucleic acids (TNAs) are gaining increasing interest in the treatment of severe diseases including viral infections, inherited disorders, and cancers. However, the efficacy of intracellularly functioning TNAs is also reliant upon their delivery into the cellular environment, as unmodified nucleic acids are unable to cross the cell membrane mainly due to charge repulsion. Here we show that TNAs can be effectively delivered into the cellular environment using engineered nanoscale metal-organic frameworks (nanoMOFs), with the additional ability to tailor which cells receive the therapeutic cargo determined by the functional moieties grafted onto the nanoMOF's surface.

Porous Metal-Organic Framework Nanoparticles.

Metal-organic frameworks (MOFs) are hybrid crystalline particles composed of metal cations and organic linkers [...

Porous nanoparticles with engineered shells release their drug cargo in cancer cells.

Highly porous nanoscale metal-organic frameworks (nanoMOFs) attract growing interest as drug nanocarriers. However, engineering "stealth" nanoMOFs with poly(ethylene glycol) (PEG) coatings remains a main challenge. Here we address the goal of coating nanoMOFs with biodegradable shells using novel cyclodextrin (CD)-based oligomers with a bulky structure to avoid their penetration inside the open nanoMOF porosity.

Facile synthesis of per(6-O-tert-butyldimethylsilyl)-α-, β-, and γ-cyclodextrin as protected intermediates for the functionalization of the secondary face of the macrocycles.

Per(6-O-tert-butyldimethylsilyl)-α-, β- and γ-cyclodextrin derivatives are well-known as synthetic intermediates that enable the selective mono-, partial, or perfunctionalization of the secondary face of the macrocycles. Although silylation of the primary rim is readily achieved by treatment with tert-butyldimethylsilyl chloride in the presence of pyridine (either alone or mixed with a co-solvent), the reaction typically results in a mixture containing both under- and oversilylated byproducts that are difficult to remove. To address this challenge in preparing a pure product in high yield, we describe an approach that centers on the addition of a controlled excess of silylating agent to avoid the presence of undersilylated species, followed by the removal of oversilylated species by column chromatography elution with carefully designed solvent mixtures.

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

Core-shell nanoparticles (NPs) are attracting increasing interest in nanomedicine as they exhibit unique properties arising from the combined assets of core and shell materials. Porous nanoscale metal-organic frameworks (nanoMOFs) are able to incorporate with high payloads a large variety of drugs. Like other types of NPs, nanoMOFs need to be functionalized with engineered coatings to ensure colloidal stability, control in vivo fate and drug release.

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.

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

A simple and green synthetic protocol for the rapid and effective preparation of Ag, Au and Au@Ag core-shell nanoparticles (NPs) is reported based on the light irradiation of a biocompatible, water-soluble dextran functionalized with benzophenone (BP) in the presence of AgNO , HAuCl , or both. Photoactivation of the BP moiety produces the highly reducing ketyl radicals through fast (<50 ns) intramolecular H-abstraction from the dextran scaffold, which, in turn, ensures excellent dispersibility of the obtained metal NPs in water. The antibacterial activity of the AgNPs and the photothermal action of the Au@Ag core-shell are also shown.

Comb-like dextran copolymers: A versatile strategy to coat highly porous MOF nanoparticles with a PEG shell.

Nanoparticles made of metal-organic frameworks (nanoMOFs) are becoming of increasing interest as drug carriers. However, engineered coatings such as poly(ethylene glycol) (PEG) based ones are required to prevent nanoMOFs recognition and clearance by the innate immune system, a prerequisite for biomedical applications. This still presents an important challenge due to the highly porous structure and degradability of nanoMOFs.

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.

Mannoside and 1,2-mannobioside β-cyclodextrin-scaffolded NO-photodonors for targeting antibiotic resistant bacteria.

Two β-cyclodextrin derivatives randomly appended on the primary face with both the nitric oxide (NO) photodonor 4-nitro-3-(trifluoromethyl)aniline and a mannose or α(1→2)mannobioside residue are reported to construct targeted NO photoreleasing nanocarriers. 2D ROESY and PGSE NMR suggested supramolecular homodimerization in water by inclusion of the nitroaniline group into the facing macrocycle cavities. Isothermal titration calorimetry on their concanavalin A lectin binding showed an exothermic binding event to the lectin and an endothermic process during the dilution of the conjugates.

A non-covalent "click chemistry" strategy to efficiently coat highly porous MOF nanoparticles with a stable polymeric shell.

Background: Metal-organic framework nanoparticles (nanoMOFs) are biodegradable highly porous materials with a remarkable ability to load therapeutic agents with a wide range of physico-chemical properties. Engineering the nanoMOFs surface may provide nanoparticles with higher stability, controlled release, and targeting abilities. Designing postsynthetic, non-covalent self-assembling shells for nanoMOFs is especially appealing due to their simplicity, versatility, absence of toxic byproducts and minimum impact on the original host-guest ability.

Electrochemical detection of glutathione S-transferase: an important enzyme in the cell protective mechanism against oxidative stress.

Oxidative stress arises when the antioxidant capacity of cells to clean the excess production of reactive oxygen species (ROS) decreases. Several human diseases seem to be related with an increment in the oxidative stress. In this regard, GSH present in the cells works by neutralizing ROS and other xenobiotics through the glutathione S-transferase (GST) enzyme.

β-Cyclodextrin-bearing gold glyconanoparticles for the development of site specific drug delivery systems.

Three novel gold nanoparticles containing multiple long, flexible linkers decorated with lactose, β-cyclodextrin, and both simultaneously have been prepared. The interaction of such nanoparticles with β-d-galactose-recognizing lectins peanut agglutinin (PNA) and human galectin-3 (Gal-3) was demonstrated by UV-vis studies. Gal-3 is well-known to be overexpressed in several human tumors and can act as a biorecognizable target.

Femto- to micro-second photobehavior of photosensitizer drug trapped within a cyclodextrin dimer.

The interactions of 5,10,15,20-tetrakis(4-sulfonatophenyl)-porphyrin (TSPP, a singlet oxygen photosensitiser molecule) with a hexa-2,4-diynediyl bridged β-cyclodextrin dimer (CD-CD) in aqueous solutions of pH 7 were studied using steady-state UV-visible absorption/emission and femto- to millisecond time-resolved spectroscopy. TSPP forms 1 : 1 complexes with CD-CD (K(e) = 1.9 × 10(8) M(-1) at 293 K).

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

Two 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.

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).

Ferrocene labelings as inhibitors and dual electrochemical sensors of human glutathione S-transferase P1-1.

The inhibitory and sensor properties of two ferrocene conjugates, in which the ferrocene and glutathione are linked through a spacer arm of different length and chemical structure, on human Pi glutathione S-transferase, were examined by activity assays, ITC, fluorescence spectroscopy and voltammetry. Such ferrocene conjugates are strong competitive inhibitors of this enzyme with an enhanced binding affinity, the one bearing the longest spacer arm being the most potent inhibitor. Voltammetric measurements showed a strong decrease of the peak current intensity and an increase of the oxidation potential upon binding of ferrocene-glutathione conjugates to GST P1-1 showing that both conjugates can be used as dual electrochemical sensors for GST P1-1.

Identifying and characterizing binding sites on the irreversible inhibition of human glutathione S-transferase P1-1 by S-thiocarbamoylation.

Human glutathione S-transferase P1-1 (hGST P1-1) is involved in cell detoxification processes through the conjugation of its natural substrate, reduced glutathione (GSH), with xenobiotics. GSTs are known to be overexpressed in tumors, and naturally occurring isothiocyanates, such as benzyl isothiocyanate (BITC), are effective cancer chemopreventive compounds. To identify and characterize the potential inhibitory mechanisms of GST P1-1 induced by isothiocyanate conjugates, we studied the binding of GST P1-1 and some cysteine mutants to the BITC-SG conjugate as well as to the synthetic S-(N-benzylcarbamoylmethyl)glutathione conjugate (BC-SG).

Binding properties of ferrocene-glutathione conjugates as inhibitors and sensors for glutathione S-transferases.

The binding properties of two electroactive glutathione-ferrocene conjugates that consist in glutathione attached to one or both of the cyclopentadienyl rings of ferrocene (GSFc and GSFcSG), to Schistosoma japonica glutathione S-transferase (SjGST) were studied by spectroscopy fluorescence, isothermal titration calorimetry (ITC) and differential pulse voltammetry (DPV). Such ferrocene conjugates resulted to be competitive inhibitors of glutathione S-transferase with an increased binding affinity relative to the natural substrate glutathione (GSH). We found that the conjugate having two glutathione units (GSFcSG) exhibits an affinity for SjGST approximately two orders of magnitude higher than GSH.

β-Cyclodextrin dimers linked through their secondary faces with rigid spacer arms as hosts for bile salts.

A convenient synthesis of β-cyclodextrin dimers in which the two cyclodextrin units are linked by rigid tethers of relatively short length through their secondary sides is reported. Compounds hexa-2,4-diynediyl- and 1,4-phenylenediethyne-briged β-cyclodextrin dimers are obtained in good yields from mono-2-O-propargyl-β-cyclodextrin through Pd-mediated oxidative homo- and heterocoupling reactions. Isothermal titration calorimetry and NMR spectroscopy (PGSE and 2D-ROESY) are used to determine the thermodynamic parameters (K, ΔH, and TΔS°) for the complexation of such β-cyclodextrin dimers with sodium cholate, deoxycholate, and chenodeoxycholate as well as to estimate the size of the supramolecular structures.

Diuretic drug binding to human glutathione transferase P1-1: potential role of Cys-101 revealed in the double mutant C47S/Y108V.

The diuretic drug ethacrynic acid (EA), both an inhibitor and substrate of pi class glutathione S-transferase (GST P1-1), has been tested in clinical trials as an adjuvant in chemotherapy. We recently studied the role of the active site residue Tyr-108 in binding EA to the enzyme and found that the analysis was complicated by covalent binding of this drug to the highly reactive Cys-47. Previous attempts to eliminate this binding by chemical modification yielded ambiguous results and therefore we decided here to produce a double mutant C47S/Y108V by site directed mutagenesis and further expression in Escherichia coli and the interaction of EA and its GSH conjugate (EASG) examined by calorimetric studies and X-ray diffraction.

Kinetic properties and specificity of trimeric Plasmodium falciparum and human dUTPases.

Deoxyuridine 5'-triphosphate nucleotidohydrolase (dUTPase, EC 3.6.1.

Influence of the H-site residue 108 on human glutathione transferase P1-1 ligand binding: structure-thermodynamic relationships and thermal stability.

The effect of the Y108V mutation of human glutathione S-transferase P1-1 (hGST P1-1) on the binding of the diuretic drug ethacrynic acid (EA) and its glutathione conjugate (EASG) was investigated by calorimetric, spectrofluorimetric, and crystallographic studies. The mutation Tyr 108 --> Val resulted in a 3D-structure very similar to the wild type (wt) enzyme, where both the hydrophobic ligand binding site (H-site) and glutathione binding site (G-site) are unchanged except for the mutation itself. However, due to a slight increase in the hydrophobicity of the H-site, as a consequence of the mutation, an increase in the entropy was observed.