Waveguide-saturable absorber fabricated by femtosecond pulses in YAG:Cr4+ crystal for Q-switched operation of Yb-fiber laser

A waveguide-saturable absorber with low propagation loss is fabricated by femtosecond pulses in YAG:Cr4+ crystal. Q-switch operation of a Yb fiber laser with the new saturable absorber having absorption saturation parameters similar to the bulk YAG:Cr4+ crystal is demonstrated

Evaluation of a cationic calix[4]arene: Solubilization and self-aggregation ability

Water-soluble calixarenes are promising macrocyclic compounds which have found numerous applications in chemistry and biology. However, these compounds have been less studied in regard to their behavior in aqueous solutions and mechanisms of drug solubilization. The present work is devoted to the evaluation of the solubilizing properties and estimation of self-aggregation ability of positively charged 5,11,17,23-tetrakis(trimethylammoniomethyl)-25,26,27,28-tetrapropoxy-calix[4]arene tetrachloride (aminocalix), including comparisons with a series of pharmaceutically relevant cyclodextrins. Phase-solubility measurements of the drugs with aminocalix and various cyclodextrins were carried out. Aminocalix showed a solubilizing ability comparable to the cyclodextrins. The drug solubility enhancement caused by the aminocalix was studied and was found to be maximal for steroid drugs. An attempt to understand the solubilizing mechanism of aminocalix was undertaken based on correlation analysis between physical and physico-chemical properties of the drugs from one side and the solubilizing ability of aminocalix from the other. Correlation analysis supports the supposition that the solubilizing effect of aminocalix is based on interaction of the drug with aminocalix aggregates rather than on inclusion complexation. UV-absorbance, osmolality and surface tension concentration dependences of aminocalix showed an inflection at 1% (w/v) which was initially related to the transition from monomers to micelles. However, dynamic light scattering and transmission electron microscopy measurements revealed that likely vesicles of diverse size exist at 0.1% (w/v) concentration. Thus the 1% (w/v) inflection point was interpreted to be spontaneous reordering of the vesicles between two different size populations

Cationic quaternized aminocalix[4]arenes: Cytotoxicity, haemolytic and antibacterial activities

This study reports the characterization of three cationic amphiphillic aminocalix[4]arenes as potential antimicrobial agents in vitro. In cytotoxicity tests on mouse macrophage RAW 264.7 cells aminocalix[4]arenes 1 and 3 showed no toxicity up to 200 and 100 μM concentrations, respectively, while 2 was non-toxic only up to 50 μM. With regard to the haemolytic activity on rabbit red blood cells, 1 was not active at concentrations up to 100 μM in contrast to the other two studied macrocycles. Compounds showed negligible ability to protect either mouse macrophage RAW 264.7 cells from anthrax lethal toxin of Bacillus anthracis (B. anthracis) or rabbit red blood cells from α-haemolysin of Staphylococcus aureus (S. aureus) in comparison to amino-β-cyclodextrins. However, all aminocalix[4]arenes showed potential as antimicrobials. Their minimum inhibitory concentrations (MIC) against Escherichia coli (E. coli) and S. aureus were in the 16-32 μg/ml concentration range, while minimum lethal concentrations (MLC) varied from 16 to 256 μg/ml depending on the bacteria and aminocalix[4]arene considered. Macrocycle 1 showed partial synergism against S. aureus in tandem with a model antibacterial drug, fusidic acid, at certain concentration combinations

γ-Cyclodextrin nanoparticle eye drops with dorzolamide: effect on intraocular pressure in man.

To access publisher's full text version of this article click on the hyperlink at the bottom of the pageTo test a new drug delivery platform with dorzolamide γ-cyclodextrin (γCD) nanoparticle eye drops for intraocular pressure (IOP) control and safety and compare with Trusopt.(®)Self-aggregating γCD nanoparticle eye drops containing 3% dorzolamide were given once a day (QD) and compared with Trusopt given three times a day (TID) in a prospective randomized single masked crossover trial over 24 h. Seventeen subjects with IOP over 18 mmHg were recruited. IOP was measured with an Icare Tonometer Pro.(®) Results: There was no statistically significant difference in the IOP lowering effect of dorzolamide nanoparticle eye drops QD and Trusopt TID. At peak (4 h), the IOP reduction from baseline was 3.8±2.6 mmHg (18%, P0.05) in nanoparticle eye drop group and 1.5±2.0 mmHg (7%, P>0.05) in the Trusopt group (P=0.23 between groups). Burning sensation measured on the visual analogue scale (1-100) was less from the nanoparticle eye drops (12±15) than from the Trusopt (37±30), (P=0.0038). Visual acuity and conjunctival hyperemia did not differ between the two groups.Dorzolamide cyclodextrin nanoparticle eye drops QD lower IOP and the effect seems comparable to Trusopt given TID. The nanoparticle eye drops are well tolerated and seem to have a better safety profile than Trusopt

A Prototype Method for the Detection and Recognition of Pigments in the Environment Based on Optical Property Simulation

The possibility of pigment detection and recognition in different environments such as solvents or proteins is a challenging, and at the same time demanding, task. It may be needed in very different situations: from the nondestructive in situ identification of pigments in paintings to the early detection of fungal infection in major agro-industrial crops and products. So, we propose a prototype method, the key feature of which is a procedure analyzing the lineshape of a spectrum. The shape of the absorption spectrum corresponding to this transition strongly depends on the immediate environment of a pigment and can serve as a marker to detect the presence of a particular pigment molecule in a sample. Considering carotenoids as an object of study, we demonstrate that the combined operation of the differential evolution algorithm and semiclassical quantum modeling of the optical response based on a generalized spectral density (the number of vibronic modes is arbitrary) allows us to distinguish quantum models of the pigment for different solvents. Moreover, it is determined that to predict the optical properties of monomeric pigments in protein, it is necessary to create a database containing, for each pigment, in addition to the absorption spectra measured in a predefined set of solvents, the parameters of the quantum model found using differential evolution

Antifungal drug solubilizing activity and self-aggregation ability of cationic aminocalix[4]arene in comparison to SBEβCD:effect of addition of water-soluble polymer

Ionized calixarene derivatives often possess properties of typical surfactants, aggregating in aqueous solutions. Their solubilizing properties, in this case, are often greater than conventional excipients, cyclodextrins. This in addition to their reported low toxicity makes these compounds promising pharmaceutical excipients. In this study we investigate the solubilizing ability of a cationic aminocalix[4]arene (CALIX), towards antifungal drugs, alone and with addition of HPMC. Next, the compound's self-aggregation properties in the presence of drug alone or in conjunction with polymer were studied using DLS, and compared to that for SBEβCD. Twenty percent (w/v) CALIX solution solubilizes antifungal drugs more efficiently than SBEβCD, improving for example the solubility of clotrimazole more than 21,000 times compared to its intrinsic solubility, and addition of 0.25 % HPMC into complexation media increases this effect further. Introduction of drug alone or in combination with the polymer into the complexation media significantly changes the microenvironment of excipient's aqueous solution, resulting either in smaller or larger aggregates depending on the drug chosen, presence of the polymer or the excipient used. Growth of the aggregates is observed to a greater extent upon introduction of clotrimazole into the media than with econazole nitrate and in some cases the particles were large enough to be observed by conventional light microscopy

Solvation and hydration characteristics of ibuprofen and acetylsalicylic acid

Ibuprofen and acetylsalicylic acid were studied by thermoanalytical methods: sublimation calorimetry, solution calorimetry, and with respect to solubility. Upon measuring the temperature dependences of the saturated vapor pressure, enthalpies of sublimation, ΔHsub0, as well as the entropies of sublimation, ΔHsub0, and their respective relative fractions in the total process were calculated. The Gibbs energy of solvation in aliphatic alcohols as well as the enthalpic and entropic fractions thereof were also studied and compared with the respective properties of model substances and other nonsteroidal antiinflammatory drugs (benzoic acid, diflunisal, flurbiprofen, ketoprofen, and naproxen). In all cases, enthalpy was found to be the driving force of the solvation process. Correlations were derived between Gibbs energy of solvation in octanol, ΔGsolvOct, and the transfer Gibbs energy from water to octanol, ΔGtr0. Influence of mutual octanol and water solubilities on the driving force of partitioning is discussed. An enthalpy-entropy-compensation effect in octanol was observed, and consequences of deviation from the general trend are also discussed