Search results for "Azide"

Amphiphilic Polysaccharide Block Copolymers for pH-Responsive Micellar Nanoparticles

2017

A full polysaccharide amphiphilic block copolymer was prepared from end group-functionalized dextrans using copper-mediated azide-alkyne click chemistry. Sufficient modification of the reducing end in both blocks was achieved by microwave-enhanced reductive amination in a borate-buffer/methanol solvent system. The combination of a hydrophilic dextran block with a hydrophobic acetalated dextran block results in an amphiphilic structure that turns water-soluble upon acid treatment. The material has a low critical micelle concentration and self-assembles in water to spherical micellar nanoparticles. The formed nanoparticles have a narrow size distribution below 70 nm in diameter and disassembl…

HPMA-Based Nanocarriers for Effective Immune System Stimulation.

2019

The selective activation of the immune system using nanoparticles as a drug delivery system is a promising field in cancer therapy. Block copolymers from HPMA and laurylmethacrylate-co-hymecromone-methacrylate allow the preparation of multifunctionalized core-crosslinked micelles of variable size. To activate dendritic cells (DCs) as antigen presenting cells, the carbohydrates mannose and trimannose are introduced into the hydrophilic corona as DC targeting units. To activate DCs, a lipophilic adjuvant (L18-MDP) is incorporated into the core of the micelles. To elicit an immune response, a model antigen peptide (SIINFEKL) is attached to the polymeric nanoparticle-in addition-via a click rea…

A Theoretical Study of the Relationship between the Electrophilicity ω Index and Hammett Constant σp in [3+2] Cycloaddition Reactions of Aryl Azide/A…

2016

The relationship between the electrophilicity ω index and the Hammett constant σp has been studied for the [2+3] cycloaddition reactions of a series of para-substituted phenyl azides towards para-substituted phenyl alkynes. The electrophilicity ω index—a reactivity density functional theory (DFT) descriptor evaluated at the ground state of the molecules—shows a good linear relationship with the Hammett substituent constants σp. The theoretical scale of reactivity correctly explains the electrophilic activation/deactivation effects promoted by electron-withdrawing and electron-releasing substituents in both azide and alkyne components.

The Low-Affinity ATP Binding Site of the Escherichia coli SecA Dimer Is Localized at the Subunit Interface

1997

The homodimeric SecA protein is the ATP-dependent force generator in the Escherichia coli precursor protein translocation cascade. SecA contains two essential nucleotide binding sites (NBSs), i.e., NBS1 and NBS2 that hind ATP with high and low affinity, respectively. The photoactivatable bifunctional cross-linking agent 3'-arylazido-8-azidoadenosine 5'-triphosphate (diN(3)ATP) was used to investigate the spatial arrangement of the nucleotide binding sites of SecA, DiN(3)ATP is an authentic ATP analogue as it supports SecA-dependent precursor protein translocation and translocation ATPase, UV-induced photo-cross-linking of the diN(3)ATP-bound SecA results in the formation of stable dimeric s…

The azido ligand: a useful tool in designing chain compounds exhibiting alternating ferro- and antiferro-magnetic interactions

1997

A one-pot reaction of NiII 1, CoII 2, FeII 3 and MnII 4 with 2,2A-bipyridine (bipy) and azide in water leads to [M(bipy)(N3)2]n chains where the metal ion is alternatively bridged by double end-on (EO) and end-to-end (EE) azido bridges; theoretical analysis of the variable-temperature magnetic susceptibility data of 1 and 4 reveals the occurrence of intrachain alternating ferro- (through EO) and antiferro-magnetic (through EE) interactions. Julve Olcina, Miguel, Miguel.Julve@uv.es ; Lloret Pastor, Francisco, Francisco.Lloret@uv.es ; Clemente Juan, Juan Modesto, Juan.M.Clemente@uv.es

Losartan reduces microalbuminuria in hypertensive microalbuminuric type 2 diabetics.

2001

Background. The aim of the present study was to assess the antialbuminuric effect of losartan in a large number of hypertensive type 2 diabetics. Methods. This was a 6-month, open-label, prospective and multicentre study. A total of 422 patients with type 2 diabetes who were hypertensive [sitting systolic blood pressure (SBP) > 140 mmHg and/or diastolic blood pressure (DBP) ≥90 mmHg] and microalbuminuric [urinary albumin excretion (UAE) 30-300 mg/day] were eligible for the study. After a 2-week run-in period, patients were placed on losartan 50 mg once a day. If the BP did not reach the desired goal (<140/90 mmHg) after a 4-week period, the losartan dose was doubled. In the absence of contr…

Thrombocytopenia Associated With Levodopa Treatment

2003

FI-chemiluminometric study of thiazides by on-line photochemical reaction

2004

The present manuscript deals with a simple and sensitive flow-injection method for the chemiluminescent determination of thiazides. The method is based on the on-line photodegradation and chemiluminescent determination of the resulting photo-fragments. The on-line photodegradation is performed in basic medium by using a photoreactor consisting of a 550 cm long x 0.8 mm ID piece of PTFE tubing helically coiled around an 8 W low-pressure mercury lamp. The determination of the photo-irradiated thiazides is performed by a chemiluminescent oxidative reaction with Ce(IV) in sulphuric acid medium. A heterogeneous group of thiazides (indapamide, metolazone, hydroflumethiazide, chlorthalidone and be…

Computational Study on Cesium Azide Trapped in a Cyclopeptidic Tubular Structure

2008

The structures and the electronic properties of host-guest complexes formed by a cyclopeptidic tubular aggregate and the species CsN3, CS2(N-3)(2), and CS2N6 have been investigated by means of density functional theory. Taking advantage of the azide property to act as a bridge ligand between two or more metal cations, it may be possible to trap N-3(-) ions inside a confined space. This could be important for the preparation of polynitrogen molecules N-n. Results show that there are significant attractive interactions between the azide ion and the cavity walls, which make the ion stay inside the inner empty space of the cyclopeptidic aggregate. The confinement of the species CS2(N-3)(2) forc…

Magnetic Properties of End-to-End Azide-Bridged Tetranuclear Mixed-Valence Cobalt(III)/Cobalt(II) Complexes with Reduced Schiff Base Blocking Ligands…

2019

Two tetranuclear mixed-valence cobalt(III/II) complexes having the general formula [(μ1,3-N3){CoII(Ln)(μ-O2CC6H4NO2)CoIII(N3)}2]PF6 (where H2L1 and H2L2 are two reduced Schiff base ligands) have been synthesized and characterized. The structures of both complexes show cobalt(II) and cobalt(III) centers with a distorted octahedral geometry with cobalt(III) and cobalt(II) centers located at the inner N2O2 and outer O4 cavities of the reduced Schiff base ligands, respectively. The oxidation states of both cobalt centers have been confirmed by bond valence sum (BVS) calculations. The magnetic properties show that both compounds behave as cobalt(II) dimers connected through an end-to-end azido b…