New cyclen-cored dendrimers functionalized with pyrene: Synthesis characterization,optical and photophysical properties

New cyclen (1,4,7,10-teraazacyclododecane) cored dendrimers up to the second generation, functionalized with 4, 8 and 16 pyrene units, respectively, were synthesized following a convergent procedure. All new compounds were characterized by NMR spectroscopies and ESI or MALDI TOF mass spectrometry. The optical and photophysical properties of the new dendrimers were studied in THF solution. Absorption spectra showed the typical absorption bands of pyrene moieties. In the fluorescence spectra, monomer as well as excimer emission were observed for all compounds. An increased proportion of excimer emission was observed in the dendrimer of the highest generation.     

Mannose‐6‐Phosphate Receptor: A Target for Theranostics of Prostate Cancer

The development of personalized and non‐invasive cancer therapies based on new targets combined with nanodevices is a major challenge in nanomedicine. In this work, the over‐expression of a membrane lectin, the cation‐independent mannose 6‐phosphate receptor (M6PR), was specifically demonstrated in prostate cancer cell lines and tissues. To efficiently target this lectin a mannose‐6‐phosphate analogue was synthesized in six steps and grafted onto the surface of functionalized mesoporous silica nanoparticles (MSNs). These MSNs were used for in vitro and ex vivo photodynamic therapy to treat prostate cancer cell lines and primary cell cultures prepared from patient biopsies. The results demonstrated the efficiency of M6PR targeting for prostate cancer theranostic.     

Polar Diketopyrrolopyrrole‐Imidazolium Salts as Selective Probes for Staining Mitochondria in Two‐Photon Fluorescence Microscopy

Three rationally designed polar derivatives of diketopyrrolopyrrole consisting of 1,3‐dimethylimidazolium cationic units and benzene, thiophene, or furan rings as π spacers were synthesized and thoroughly studied. The obtained salts are soluble in polar organic solvents and show satisfactory solubility in water, which makes them suitable for the applications in bioimaging. Photophysical measurements revealed that the obtained derivatives are characterized by strong absorption and good fluorescence quantum yields. The corresponding two‐photon properties were also examined and showed that the synthesized salts exhibit large two‐photon absorption cross‐sections reaching 4000 GM (GM=Goeppert‐Mayer unit, 1 GM=10^?50 cm⁴ s photon^?1) and very high two‐photon brightness values exceeding 2000 GM. It was demonstrated that these salts can be safely applied in two‐photon fluorescence microscopy for selective staining of mitochondria in living cells.     

Conservation laws of an electro-active polymer

Ionic electro-active polymer is an active material consisting in a polyelectrolyte (for example Nafion). Such material is usually used as thin film sandwiched between two platinum electrodes. The polymer undergoes large bending motions when an electric field is applied across the thickness. Conversely, a voltage can be detected between both electrodes when the polymer is suddenly bent. The solvent-saturated polymer is fully dissociated, releasing cations of small size. We used a continuous medium approach. The material is modelled by the coexistence of two phases; it can be considered as a porous medium where the deformable solid phase is the polymer backbone with fixed anions; the electrolyte phase is made of a solvent (usually water) with free cations. The microscale conservation laws of mass, linear momentum and energy and the Maxwell’s equations are first written for each phase. The physical quantities linked to the interfaces are deduced. The use of an average technique applied to the two-phase medium finally leads to an Eulerian formulation of the conservation laws of the complete material. Macroscale equations relative to each phase provide exchanges through the interfaces. An analysis of the balance equations of kinetic, potential and internal energy highlights the phenomena responsible of the conversion of one kind of energy into another, especially the dissipative ones : viscous frictions and Joule effect.     

Ab initio study of the influence of aggregation on the infrared spectrum of acetonitrile

With the aim of investigating the influence of direct intermolecular interactions between nitrile groups on the infrared features of nitrile polymers, vibrational frequencies and infrared intensities of acetonitrile and of its antiparallel dimer are compared. It is found that whereas frequencies are unchanged upon association infrared intensities are dramatically affected. In particular, the striking difference between the intensities of the CN stretching band measured in gas phase, on the one hand, and in the liquid, on the other, is already accounted for at the dimer level. Despite the poor reliability of absolute values of calculated intensities, it is interesting to note that consistent trends are obtained at various levels of theory. These results suggest that ab initio calculations of infrared intensities can be useful to interpret infrared measurements, thus contributing to the elucidation of molecular structure of materials. © 1993 John Wiley & Sons, Inc.     

New enumerative results on two-dimensional directed animals

We list several open problems concerning the enumeration of directed animals on two-dimensional lattices. We show that most of these problems are special cases of two central problems: calculating the position generating function and the perimeter and area generating function for square lattice animals.

We propose a possible direction for solving these two problems: we extend Dhar's correspondence between hard particle gas models and enumeration of animals according to the area, and show that each of the main two generating functions is, essentially, the density of a one-dimensional gas model given by the stationary distribution of a probabilistic transition.

We are able to compute the density of certain stationary distributions. We thus obtain new bivariate generating functions for directed animals on the square and triangular lattices. We derive from these results the generating functions for animals on the decorated square and triangular lattices, as well as the average number of loops in directed animals.     

Investigation of ion-selective electrodes with neutral ionophores and ionic sites by EIS. II. Application to K detection

The impedance of an ion-selective electrode (ISE) to potassium with valinomycin as the ionophore and KBΦ₄ as the ionic sites was measured. The membrane was made of PVC with DNP as a plasticizer. The influence of the content of the plasticizer and the membrane thickness was investigated. The concentrations of the ionophore and the ionic sites were changed to modify the response on the ISE. Finally, the selectivity was tested in terms of impedance. All impedance experiments were correlated to the potentiometric curves plotted under the same experimental conditions. The measured impedances were compared to the model proposed in the previous paper (paper I). A good agreement was found.     

Photothermal deflection microscopy for imaging sub-micronic defects in optical materials

Photothermal deflection is widely used to study defects in optical coatings and role of these defects in laser damage. Because defects responsible for laser damage are assumed to be nanometer-sized and lowly absorbing, both high spatial resolution and high sensitivity are required to detect them. In this work we theoretically and experimentally explore the capability of collinear photothermal deflection to give micronic resolution by reduction of the pump beam diameter. Thanks to a model describing temperature distribution and photothermal deflection, we have studied the effects of pump beam focusing on photothermal deflection. Then, we have developed a high resolution, high sensitivity microscope based on the photothermal deflection of a transmitted probe beam. The setup is characterized and the theoretical predictions are checked. We present a test of lateral spatial resolution obtained on specially prepared absorbing resolution targets and show that a lateral spatial resolution of 1 μm is reached on non-isolated defects. In case of single defects, we expect that 10 nm sized defects could be detected.     

Cameroonian medicinal plants belonging to Annonaceae family: radical scavenging and antifungal activities

The free-radical scavenging activity of ethanolic and methanolic extracts of leaves, stems and roots of Annona muricata, Monodora tenuifolia, Uvaria comperei, Uvaria muricata and Xylopia africana was evaluated using DPPH and ORAC assays. Further, phytochemical analysis, total phenolic and total flavonoid contents were also determined. Moreover, the antifungal activity of extracts was studied. The findings indicated that A. muricata and U. comperei extracts own antiradical activities and moderate antifungal properties.