Haemolytic properties of some water-soluble para-sulphonato-calix-[n]-arenes

In this paper, we describe the haemolytic effect of parent para-sulphonato-calix-[n]-arenes and their derivatives bearing one pendant group at the lower rim of calix-arene towards human erythrocytes. A maximum of 30% of haemolysis has been observed for para-sulphonato-calix-[8]-arene for a concentration of 200 mM representing 300 g of calix-arene per liter of human blood, para-sulphonato-calix-[4]-arene and para-sulphonato-calix-[6]-arene show much lower haemolytic effects, 0.5 and 8%, respectively at 200 mM concentration. Coupling of a methoxy-carboxylate function at the phenolic group reduces haemolytic effects in all cases. The presence of an ethoxy-amine function increases the haemolytic behaviour for the calix-[4]-arene and calix-[6]-arene systems, but reduces the effect for the calix-[8]-arene derivatives.

Solid-state caging of 1,10-phenanthroline π–π stacked dimers by calix[4]arene dihydroxyphosphonic acid

The calix[4]arene dihydroxyphosphonic acid-1,10-phenanthroline complex shows caging of the guest molecules as a pi-pi stacked dimer in a cavity formed by intermolecular hydrogen bonds and aromatic walls formed by the calixarene.

A new packing motif for para-sulfonatocalix[4]arene: the solid state structure of the para-sulfonatocalix[4]arene d-arginine complex

The solid-state structure of the complex of para-sulfonatocalix[4]arene with d-arginine, contains a water channel diagonal to a zigzag bilayer of the host, within the bilayer six crystallographically independent molecules of arginine are present, four being included in the calix cavities.

Changing the conformation state of cytochrome b558 initiates NADPH oxidase activation: MRP8/MRP14 regulation

Phagocyte NADPH oxidase generates O2. for defense mechanisms and cellular signaling. Myeloid-related proteins MRP8 and MRP14 of the S100 family are EF-hand calcium-binding proteins. MRP8 and MRP14 were co-isolated from neutrophils on an anti-p47phox matrix with oxidase cytosolic factors and identified by mass spectrometry. MRP8 and MRP14 are absent from Epstein-Barr virus-immortalized B lymphocytes, and, coincidentally, these cells display weak oxidase activity compared with neutrophils. MRP8/MRP14 that was purified from neutrophils enhanced oxidase turnover of B cells in vitro, suggesting that MRP8/MRP14 is involved in the activation process. This was confirmed ex vivo by co-transfection of Epstein-Barr virus-transformed B lymphocytes with genes encoding MRP8 and MRP14. In a semi-recombinant cell-free assay, recombinant MRP8/MRP14 increased the affinity of p67phox for cytochrome b558 synergistically with p47phox. Moreover, MRP8/MRP14 initiated oxidase activation on its own, through a calcium-dependent specific interaction with cytochrome b558 as shown by atomic force microscopy and a structure-function relationship investigation. The data suggest that the change of conformation in cytochrome b558, which initiates the electron transfer, can be mediated by effectors other than oxidase cytosolic factors p67phox and p47phox. Moreover, MRP8/MRP14 dimer behaves as a positive mediator of phagocyte NADPH oxidase regulation.

Interactions of amphiphilic calix[4]arene-based Solid Lipid Nanoparticles with bovine serum albumin

The interaction of Solid Lipid Nanoparticles (SLN) based on amphiphilic calix[4]arene with one of the major circulatory protein, serum albumin, has been investigated by Photon Correlation Spectroscopy (PCS) and Atomic Force Microscopy (AFM). The carrier systems have shown the ability to interact with bovine serum albumin (BSA), which forms a capping layer up to 17nm in depth. AFM imaging revealed that the SLNs are protected by this layer against flattening on surfaces.

Scanning electron microscopy and atomic force microscopy imaging of solid lipid nanoparticles derived from amphiphilic cyclodextrins

Scanning electron microscopy (SEM) and atomic force microscopy (AFM) have been applied to the imagery of solid lipid nanoparticles (SLNs) formulated from an amphiphilic cyclodextrin, 2,3-di-o-alkanoyl-beta-cyclodextrin, beta-CD21C6. Comparison of the results shows that the vacuum drying technique used in sample preparation for SEM causes shrinkage in the size of the SLNs, whereas the deposition method used for AFM causes the SLNs to form small clusters. The hydrodynamic diameter determined from photon correlation spectroscopy (PCS) is 359+/-15 nm and the zeta potential is -25 mV.

The structure of a self-assembled calixarene aqua-channel system

The crystal structure of the complex 12.calix-[4]-arene dihydroxyphosphonic acid, 12.propane diammonium, 12.ethanol and 40.water molecules is based on dimeric units of the calix, assembled via trigonal units into a hexameric tube of 15 A radius and 16 A depth, further assemby via spanning propane diammonium cations and ethanol molecules forms a channel (40 A), selectively containing all the water molecules.

Para-acyl-calix-arene based solid lipid nanoparticles (SLNs): a detailed study of preparation and stability parameters

The preparation and stability parameters of para-acyl-calix[4]arene based solid lipid nanoparticles (SLNs) have been investigated. Atomic force microscopy (AFM) and photon correlation spectroscopy (PCS) show a mean particle size of 130 nm. In terms of preparation parameters, using the solvent displacement method, the nature and the volume of the organic solvent, the concentration of the amphiphile and the presence of a co-surfactant in the organic phase have been shown to affect significantly the size of the produced SLNs. In contrast, the stirring speed, the viscosity and the acidity of the aqueous phase and the amphiphile hydrophobic chain length have been shown to have no effect. In terms of stability parameters, the ionic strength has been shown to affect the short-time SLN stability depending on both the anion and the cation studied, with sodium sulphate causing precipitation. Ultrasonic, ultraviolet or microwave treatments of the SLN suspensions have no effect on the size of the SLNs. The study of the effects of short time thermal treatment revealed that the SLNs are not affected by one freezing-defreezing cycle and are stable at 100 degrees C in suspension. It is difficult to reconstitute the SLN suspensions after freeze-drying. Finally, the temporal stability of these suspensions in water has been shown to be superior to 1 year. The long-term temporal stability of suspensions stored in saline solution has been investigated. It has been demonstrated that the most destabilising effects arise from the presence in the storage suspension of sulphate ions.1H NMR, X-ray powder diffraction (XPD) and AFM have also been carried out on the calix-arene based SLNs and demonstrate the presence of a semi-organised matrix structure for the SLNs.

A study of the freeze-drying conditions of calixarene based solid lipid nanoparticles

In this note, we report a study of cryoprotectant carbohydrate (glucose, fructose, mannose and maltose) effects on the reconstitution of calixarene based solid lipid nanoparticle (SLN) suspensions after freeze-drying, studied by atomic force microscopy and photon correlation spectroscopy. All carbohydrates tested showed excellent cryoprotection and redispersion properties with the calixarene based SLNs.

Interfacial interactions between amphiphilic cyclodextrins and physiologically relevant cations

The compression isotherms of a series of amphiphilic cyclodextrins, formed (a) by acylation at the secondary hydroxyl face and (b) by acylation accompanied by varying degrees of sulfatation (DS) at the primary hydroxyl face (DS=0, 4, and 7), have been studied on subphases of pure water and of water containing NaCl, KCl, MgCl(2), and CaCl(2) at inter- and extracellular concentrations. The formation of solid lipid nanoparticles (SLNs) by two of the molecules has been observed, while these do not aggregate at concentrations of monovalent salts up to 150 mM for the sulfated derivative. In the presence of divalent salts one of these with a DS=0 for sulfatation degree flocculates at divalent salt concentrations below 0.1 mM while the other with a DS=4 flocculates at Mg(2+) concentration above 5 mM and a Ca(2+) concentration above 3 mM. AFM noncontact mode imaging has been carried out, in air, for the SLNs deposited on mica.

AFM imaging of calixarene based solid lipid nanoparticles in gel matrices

Contact mode atomic force microscopy has been carried out on gels of four current polymers, carbopol 980, carbopol 2020, hyaluronic acid and xanthan containing dispersions of solid lipid nanoparticles (SLNs) of amphiphilic calixarenes. Imaging shows that the SLNs are dispersed within the gels as discrete particles of 150nm in diameter and show little or no aggregation. The simultaneous use of lateral force, topographic and force modulation mode imaging allows a clear interpretation of the observed images, showing the presence of nanoparticles in the sub-surface region and that the SLNs affect the local mechanical properties of the gels. Photon correlation spectroscopy similarly demonstrates a lack of interaction in suspensions.

Atomic force microscopy imaging of novel type of polymeric colloidal nanostructures

Polymeric nanoparticles were prepared by the interfacial poly-condensation of the lipophilic monomer, phtaloyldichloride and the hydrophilic monomer, diethylenetriamine, in the presence and absence of the surfactant Pluronic F68. The colloidal systems were analysed by dynamic light scattering and atomic force microscopy, the structures formed have two populations (150 and 350 nm) in the presence of the surfactant and one population (450 nm) in the absence of the surfactant. The results can be interpreted in terms of the formation of hollow nanocapsules that collapse on deposition and drying.