Drug-Loaded Polymeric Particulated Systems for Ophthalmic Drugs Release

Drug delivery to the anterior or posterior segments of the eye is a major challenge due to the protection barriers and removal mechanisms associated with the unique anatomical and physiological nature of the ocular system. The paper presents the preparation and characterization of drug-loaded polymeric particulated systems based on pre-emulsion coated with biodegradable polymers. Low molecular weight biopolymers (chitosan, sodium hyaluronate and heparin sodium) were selected due to their ability to attach polymer chains to the surface of the growing system. The particulated systems with dimensions of 190–270 nm and a zeta potential varying from −37 mV to +24 mV depending on the biopolymer charges have been obtained. Current studies show that particles release drugs (dexamethasone/pilocarpine/bevacizumab) in a safe and effective manner, maintaining therapeutic concentration for a longer period of time. An extensive modeling study was performed in order to evaluate the drug release profile from the prepared systems. In a multifractal paradigm of motion, nonlinear behaviors of a drug delivery system are analyzed in the fractal theory of motion, in order to correlate the drug structure with polymer. Then, the functionality of a SL(2R) type “hidden symmetry” implies, through a Riccati type gauge, different “synchronization modes” (period doubling, damped oscillations, quasi-periodicity and intermittency) during the drug release process. Among these, a special mode of Kink type, better reflects the empirical data. The fractal study indicated more complex interactions between the angiogenesis inhibitor Bevacizumab and polymeric structure.     

Design and evaluation of a new Peltier-cooled laser ablation cell with on-sample temperature control

A new custom-built Peltier-cooled laser ablation cell is described. The proposed cryogenic cell combines a small internal volume (20 cm³) with a unique and reliable on-sample temperature control. The use of a flexible temperature sensor, directly located on the sample surface, ensures a rigorous sample temperature control throughout the entire analysis time and allows instant response to any possible fluctuation. In this way sample integrity and, therefore, reproducibility can be guaranteed during the ablation. The refrigeration of the proposed cryogenic cell combines an internal refrigeration system, controlled by a sensitive thermocouple, with an external refrigeration system. Cooling of the sample is directly carried out by 8 small (1 cm × 1 cm) Peltier elements placed in a circular arrangement in the base of the cell. These Peltier elements are located below a copper plate where the sample is placed. Due to the small size of the cooling electronics and their circular allocation it was possible to maintain a peephole under the sample for illumination allowing a much better visualization of the sample, a factor especially important when working with structurally complex tissue sections. The analytical performance of the cryogenic cell was studied using a glass reference material (SRM NIST 612) at room temperature and at −20 °C. The proposed cell design shows a reasonable signal washout (signal decay within less than 10 s to background level), high sensitivity and good signal stability (in the range 6.6–11.7%). Furthermore, high precision (0.4–2.6%) and accuracy (0.3–3.9%) in the isotope ratio measurements were also observed operating the cell both at room temperature and at −20 °C. Finally, experimental results obtained for the cell application to qualitative elemental imaging of structurally complex tissue samples (e.g. eye sections from a native frozen porcine eye and fresh flower leaves) demonstrate that working in cryogenic conditions is critical in such type of direct sample analysis.     

Triazene UV-triggered photogeneration of silver/gold nanoparticles in block copolymer templates

Journal of Nanoparticle Research - Synthesis of yttrium oxide nanoparticles in a specially designed radio frequency thermal plasma reactor is reported. Good crystallinity, narrow size distribution,...     

Transition and post-transition metal ion chemistry of dibenzo-substituted,mixed-donor macrocycles incorporating five donor atoms

The transition and post-transition metal ion chemistry of a wide range of potentially pentadentate dibenzo-substituted macrocyclic ligands incorporating nitrogen, oxygen and/or sulfur donors is reviewed and shown to result in a diverse range of structural types. Aspects of metal ion recognition, bulk membrane transport, systems incorporating appended chromophores, a sulfate binding system, induced Cu(I)/Cu(II) redox switching, coordination polymers, and unsymmetric macrocyclic ligand systems are all discussed.     

Rational design of new polymerizable oxyanion receptors

We report the synthesis of a library of new polymerizable functional monomers designed for complexing with the oxyanionic moiety of the chemotherapeutic drug methotrexate. The 1H NMR and ITC binding studies allowed for the selection of receptors possessing the best association parameters. Subsequently, the design of a broad library of polymerizable moiety-specific binding monomers for the imprinting of dicarboxylate containing drugs was accomplished. Di(ureidoehylenemethacrylate)stilbene possesses the highest association properties and shows potential to act as a monomer in the molecularly imprinting technique to obtain photoswitchable cavities.     

Banach spaces in which weakly p -Dunford–Pettis sets are relatively compact

In this paper we introduce p-Dunford–Pettis completely continuous operators and study Banach spaces with the wp-Dunford–Pettis relative compact property (wp-DPrcP). We study the behaviour of p-Dunford–Pettis completely operators on spaces with this property. We give sufficient conditions for spaces of operators to have the wp-DPrcP.     

BEM-Fading regularization algorithm for Cauchy problems in 2D anisotropic heat conduction

Numerical Algorithms - We investigate the numerical reconstruction of the missing thermal boundary data on a part of the boundary for the steady-state heat conduction equation in anisotropic solids...     

Synthesis of Chiral MOF-74 Frameworks by Post-Synthetic Modification by Using an Amino Acid

The synthesis of chiral metal–organic frameworks (MOFs) is highly relevant for asymmetric heterogenous catalysis, yet very challenging. Chiral MOFs with MOF-74 topology were synthesised by using post-synthetic modification with proline. Vibrational circular dichroism studies demonstrate that proline is the source of chirality. The solvents used in the synthesis play a key role in tuning the loading of proline and its interaction with the MOF-74 framework. In N,N′-dimethylformamide, proline coordinates monodentate to the Zn²⁺ ions within the MOF-74 framework, whereas it is only weakly bound to the framework when using methanol as solvent. Introducing chirality within the MOF-74 framework also leads to the formation of defects, with both the organic linker and metal ions missing from the framework. The formation of defects combined with the coordination of DMF and proline within the framework leads to a pore blocking effect. This is confirmed by adsorption studies and testing of the chiral MOFs in the asymmetric aldol reaction between acetone and para-nitrobenzaldehyde.