Synthesis and crystal structures of nickel(ii) and palladium(ii) complexes with o-carboranyl amidine ligands.

A number of new nido-carboranyl amidines 10-R(CH2)nNHC(Et)[double bond, length as m-dash]HN-7,8-C2B9H11 (n = 2, R = OH, OMe, and NMe2; n = 3, R = OH) were synthesized by the nucleophilic addition of amino alcohols and N,N-dimethylethylenediamine to the highly activated -C[triple bond, length as m-dash]N+- triple bond of the 10-propionitrilium derivative of nido-carborane. A similar reaction of 10-EtC[triple bond, length as m-dash]N-7,8-C2B9H11 with ethylenediamine unexpectedly resulted in the cleavage of the C[triple bond, length as m-dash]N bond to form the ammonium derivative 10-H3N-7,8-C2B9H11. The complexation of the synthesized carboranyl amidines 10-MeO(CH2)2NHC(Et)[double bond, length as m-dash]HN-7,8-C2B9H11 and 10-Me2N(CH2)2NHC(Et)[double bond, length as m-dash]HN-7,8-C2B9H11 with nickel and palladium phosphine complexes [(Ph3P)2MCl2] (M = Ni, Pd) was studied. The reactions with 10-MeO(CH2)2NHC(Et)[double bond, length as m-dash]HN-7,8-C2B9H11 result in half-sandwiched metallacarborane complexes with the retention of one triphenylphosphine ligand [3-Ph3P-3-(8-MeOCH2CH2N[double bond, length as m-dash]C(Et)NH)-3,1,2-MC2B9H10], while the reactions with 10-Me2N(CH2)2NHC(Et)[double bond, length as m-dash]HN-7,8-C2B9H11 proceed with the complete loss of the phosphine ligands and lead to the formation of complexes with the η5:κ2(N,N')-coordinated carboranyl amidine ligand [3,3-(8-Me2NCH2CH2N[double bond, length as m-dash]C(Et)NH)-3,1,2-MC2B9H10]. The crystal molecular structures of the synthesized complexes were determined by single crystal X-ray diffraction.

Encapsulation of vitamin B12 into nanoengineered capsules and soft matter nanosystems for targeted delivery.

Targeted delivery of vitamins to a desirable area is an active branch in a modern pharmacology. The most important and difficult delivery of vitamin B12 is that to bone marrow and nerve cells. Herein we present a first step towards the development of two types of smart carriers, polymer capsules and lyotropic liquid-crystalline nanosystems, for vitamin B12 targeted delivery and induced release. A vitamin B12 encapsulation technique into nanoengineered polymeric capsules produced by layer-by-layer assembling of polymeric shells on CaCO3 templates has been developed. The effectiveness of the process was demonstrated by optical absorption spectroscopy, transmission electron microscopy (TEM), atomic force microscopy (AFM) and small-angle X-ray diffraction. TEM and AFM analyses performed on capsules after their drying, confirmed the presence of the vitamin B12 inside the capsules in the form of crystalline nanoaggregates, 50-300 nm in diameter. Soft lipid nanovectors consisting of amphiphilic phytantriol molecules, which in water excess spontaneously self-assembly in 3D well-ordered inverse bicontinuous cubic bulk phase, were used as alternative carriers for vitamin B12. It was shown that about 30% of the vitamin added in the preparation of the soft lipid system was actually encapsulated in cubosomes and that no structural changes occurred upon loading. The Vitamin stabilizes the lipid system playing the role of its structure-forming element. The biocompatible nature, the stability and the feasibility of these systems make them good candidates as carriers for hydrophilic vitamins.

Collagen containing microcapsules: smart containers for disease controlled therapy.

The protein collagen is the major component of connective tissue and it is involved in many biological functions. Its degradation is at the basis of different pathological processes. The up-regulated expression of matrix metalloproteinases and the down-regulated expression of their inhibitors are the causes for such degradation. The aim of this work was to evaluate the possibility to fabricate collagen based containers for drug encapsulation and release by cellular demand by the action of matrix metalloproteinases. In present work collagen type I based microcapsules were fabricated by means of the layer-by-layer assembly of oppositely charged collagen and poly (stirene sulfonate) onto colloidal particles, followed by removal of the cores to obtain hollow microcapsules. The process of shell growth on planar supports was monitored by quartz crystal microbalance. X-ray reflectivity measurements were carried out at the solid/water interface to study the interaction of matrix metalloproteinase 1 with LbL films of collagen. The morphology of hollow capsules was characterized by scanning electron microscopy, and compared to that of capsules exposed to the matrix metalloproteinase 1. Finally the matrix metalloproteinase 1 mediated permeability of capsules variation was studied by Confocal Laser Scanning Microscopy. The results demonstrated the possibility to fabricate a drug delivery system where the release of the drug is dependent on the biochemistry of the pathological state.

Paclitaxel-containing nano-engineered polymeric capsules towards cancer therapy.

Paclitaxel is one of the anticancer agents most often used in clinical oncology practice for the treatment of ovarian, breast and non-small cell lung cancers. Nanoengineered polymeric capsules (NPCs) represent a new and very effective tool for the encapsulation and smart release of different compounds. In present work capsules were fabricated by means of the layer-by-layer assembly of oppositely charged polyelectrolytes onto colloidal particles, followed by removal of the cores at low pH to obtain hollow microcapsules. Paclitaxel was loaded into the capsule. As tumors exhibit a lower extracellular pH than normal tissues, the property of NPCs to open the pores in their shell at slightly acidic pH values could be used for the triggered release of paclitaxel within a tumor microenvironment. For the characterization of NPCs, quartz crystal microbalance was used to monitor the process of shell growth on planar supports. The effective encapsulation of paclitaxel was then demonstrated by atomic force microscopy and micro-Raman spectroscopy, whereas its release was characterized by Uv-vis spectroscopy. Finally the biological activity of encapsulated paclitaxel against human breast cancer cells was assessed.

Light-driven release from polymeric microcapsules functionalized with bacteriorhodopsin.

Bacteriorhodopsin was incorporated into the shell of polymeric capsules. Light-driven variation of intercapsule volume pH with successive pore opening was demonstrated by scanning electron microscopy. Release of the encapsulated dye molecules was studied by confocal fluorescence microscopy.

Electrochemical control of the conductivity in an organic memristor: a time-resolved X-ray fluorescence study of ionic drift as a function of the applied voltage.

Grazing-incidence X-ray fluorescence measurements were applied for a time-resolved study of an organic memristor conductivity variation mechanism. A comparison of these results with electrical measurements has allowed us to conclude that the variation of the fluorescence intensity of Rb ions is directly connected to the ionic charge transferred between the conducting polymer and the solid electrolyte, which made up the device. In addition, the conductivity of the memristor was shown to be a function of the transferred ionic charge.

X-ray reflectivity measurements of layer-by-layer films at the solid/liquid interface.

In this Letter, we present a method for the decoration of layer-by-layer (LbL) structures by heavy metal ions, which allows X-ray reflectivity (XRR) measurements at the solid/water interface. The improved contrast has allowed us to obtain well-structured X-ray reflectivity curves from samples at the liquid/solid interface that can be used for the film structure modeling. The developed technique was also used to follow the formation of complexes between DNA and the LbL multilayer. The XRR data are confirmed by independent null-ellipsometric measurements at the solid/liquid interface on the very same architectures.

Structural study of the DNA dipalmitoylphosphatidylcholine complex at the air-water interface.

We present here results that demonstrate the formation of a complex of DNA with zwitterionic dipalmitoylphosphatidylcholine (DPPC) monolayer at the air-water interface in the presence of Ca2+ ions; in particular, we show that the presence of Ca2+ cations is essential for the formation of the complex of DPPC with DNA. We characterize the resulting structure by X-ray reflectivity and by null-ellipsometry. We show that DNA maintains its native double helix form when attached to the zwitterionic lipid monolayer, at difference with the case of ammine containing monolayers. Our findings are discussed in view of other works that recently appeared on the interaction of DNA with zwitterionic phospholipids, emphasizing the role of DPPC as a potential vector for transfer of genetic material into mammalian cells by nonviral gene therapy and also suggesting Langmuir/Blodgett layers of zwitterionic phospoholipids as a method for nonconventional DNA immobilization.

Interaction of DNA oligomers with cationic lipidic monolayers: complexation and splitting.

Interactions of native DNA with octadecylamine (ODA) and hexadecymdimethylammonium bromide (HTAB) monolayers at the air/water interface were studied by pi-A isotherms, ellipsometry, and X-ray reflectivity. We show that the microscopic structure of ODA-DNA complexes is definitely consistent with a single-stranded form for DNA. On the contrary, with HTAB, DNA complexes in its native form. The crucial difference in the behavior of these two fairly similar lipids is due to the presence of the amine group in ODA. These results should be relevant to applications such as DNA chips and sensors.