Efficacy of copper sulphate on candida albicans on heat-polymerized acrylic resin / Eficacia del sulfato de cobre sobre candida albicans en resinas acrílicas de termocurado

The ageing of population is increasing, and a great percentage of these patients wear removable prostheses, and can suffer denture stomatitis, a condition that has been associated with candidiasis. Aims: To evaluate in vitro the effectiveness of Copper Sulfate against Candida albicans in samples of heat-polymerized acrylic resin, compared to nystatin, sodium hypochlorite and chlorhexidine. Materials and Methods: Initially, the minimum inhibitory concentration (MIC) of copper sulfate for Candida albicans was determined by microdilution. Then, 54 resin samples were divided into 6 treatment groups corresponding to Nystatin 100.000 UI, Sodium Hypochlorite 0.5%, chlorhexidine 0.12%, Copper Sulfate 4.7µg/ml, Copper Sulfate 9.4µg/ml and physiological saline solution, in which samples were submerged for 6 hours. Resin samples were then washed and cultured on solid media at 37°C for 72 hours. The number of colony-forming units was determined using a Quebec colony counter. The statistical analysis was performed using the Kruskal-Wallis test and the Mann-Whitney U test. Results: Copper sulfate at a concentration of 9.4µg/ml presented a similar effectiveness as the other control products regarding the reduction in the number of colonies of Candida albicans post-treatment. Conclusion: The effectiveness of copper sulfate against Candida albicans on acrylic resin was similar to that of nystatin, sodium hypochlorite and chlorhexidine.

En las últimas décadas se ha observado un aumento de la población de adultos mayores, de los cuales un gran porcentaje es portador de prótesis removible, y dos tercios pueden sufrir estomatitis subprotésica, enfermedad que es asociada a infecciones como candidiasis. Objetivo: Evaluar la efectividad antimicótica in vitro del sulfato de cobre en placas de resinas acrílicas de termocurado inoculadas con Candida albicans, frente a Nistatina, Hipoclorito de Sodio y Clorhexidina. Material y Métodos: Inicialmente, y mediante microdilución del sulfato de cobre, se determinó la concentración mínima inhibitoria (CMI) para Candida albicans. En la fase experimental, 54 muestras de resina se dividieron en 6 grupos correspondientes a Nistatina 100.000 UI, Hipoclorito 0.5%, Clorhexidina 0.12%, Sulfato de Cu 4.7µg/ml, Sufato de Cu 9.4 µg/ml y suero fisiológico. Las muestras fueron sumergidas en estos agentes por 6 horas, para posteriormente ser lavadas y cultivada en medios solidos a 37°C por 72 horas. Luego se realizó el conteo de unidades formadoras de colonias mediante contador tipo Quebec. El análisis estadístico se realizó mediante la prueba de Kruskal-Wallis y la prueba U de Mann-Whitney. Resultado: El sulfato de cobre a una concentración de 9.4µg/ ml presentó una efectividad similar a los otros productos, en la reducción de colonias de Candida albicans. Conclusión: La efectividad del sulfato de cobre contra Candida albicans fue semejante a la de Nistatina, Hipoclorito y Clorhexidina.

Functionalized Anion-Exchange Membranes Facilitate Electrodialysis of Citrate and Phosphate from Model Dairy Wastewater.

In this study, the preparation of a new, functional anion-exchange membrane (AEM), containing guanidinium groups as the anion-exchanging sites (Gu-100), is described as well as the membrane characterization by XPS, water uptake, permselectivities, and electrical resistances. The functional membrane was also employed in pH-dependent electrodialysis experiments using model dairy wastewater streams. The properties of the new membrane are compared to those of a commercially available anion-exchange membrane bearing conventional quaternary ammonium groups (Gu-0). Guanidinium was chosen for its specific binding properties toward oxyanions: e.g., phosphate. This functional moiety was covalently coupled to an acrylate monomer via a facile two-step synthesis to yield bulk-modified membranes upon polymerization. Significant differences were observed in the electrodialysis experiments for Gu-0 and Gu-100 at pH 7, showing an enhanced phosphate and citrate transport for Gu-100 in comparison to Gu-0. At pH 10 the difference is much more pronounced: for Gu-0 membranes almost no phosphate and citrate transport could be detected, while the Gu-100 membranes transported both ions significantly. We conclude that having guanidinium groups as anion-exchange sites improves the selectivity of AEMs. As the presented monomer synthesis strategy is modular, we consider the implementation of functional groups into a polymer-based membrane via the synthesis of tailor-made monomers as an important step toward selective ion transport, which is relevant for various fields, including water treatment processes and fuel cells.

Effect of Divalent Cations on RED Performance and Cation Exchange Membrane Selection to Enhance Power Densities.

Reverse electrodialysis (RED) is a membrane-based renewable energy technology that can harvest energy from salinity gradients. The anticipated feed streams are natural river and seawater, both of which contain not only monovalent ions but also divalent ions. However, RED using feed streams containing divalent ions experiences lower power densities because of both uphill transport and increased membrane resistance. In this study, we investigate the effects of divalent cations (Mg2+ and Ca2+) on RED and demonstrate the mitigation of those effects using both novel and existing commercial cation exchange membranes (CEMs). Monovalent-selective Neosepta CMS is known to block divalent cations transport and can therefore mitigate reductions in stack voltage. The new multivalent-permeable Fuji T1 is able to transport divalent cations without a major increase in resistance. Both strategies significantly improve power densities compared to standard-grade CEMs when performing RED using streams containing divalent cations.

Molecular Basis for the Recognition of Higher Fullerenes into Ureidopyrimidinone-Cyclotriveratrylene Self-Assembled Capsules.

Fullerenes C60 , C70 , and C84 may be readily encaged within a hydrogen-bonded dimeric capsule, based on two concave cyclotriveratrylene (CTV) scaffolds, each containing three self-complementary 2-ureido-4-[1H]-pyrimidinone (UPy) subunits. NMR spectroscopy and circular dichroism studies, complemented by dispersion-corrected DFT calculations, are reported with the aim of characterizing such capsule-fullerene complexes both structurally and energetically. Six fullerenes are considered: in agreement with experiments, calculations find that encapsulation is most favorable for C84 (on a par with C90 ), and follows the trend C60

Triggering activity of catalytic rod-like supramolecular polymers.

Supramolecular polymers based on benzene-1,3,5-tricarboxamides (BTAs) functionalized with an L- or D-proline moiety display high catalytic activity towards aldol reactions in water. High turnover frequencies (TOF) of up to 27×10(-4) s(-1) and excellent stereoselectivities (up to 96% de, up to 99% ee) were observed. In addition, the catalyst could be reused and remained active at catalyst loadings and substrate concentrations as low as 0.1 mol % and 50 mM, respectively. A temperature-induced conformational change in the supramolecular polymer triggers the high activity of the catalyst. The supramolecular polymer's helical sense in combination with the configuration of the proline (L- or D-) is responsible for the observed selectivity.

A modular approach to introduce function into single-chain polymeric nanoparticles.

Here, a modular approach is reported to introduce a specific function into single-chain polymeric nanoparticles (SCPNs). Hereto, an amphiphilic polymer with pendant benzene-1,3,5-tricarboxamide (BTA) units is mixed with a "free" BTA that contains a functional group, either a fluorescent naphthalimide or a catalytically active l-proline. Taking advantage of hydrophobic interactions and self-recognition properties of the BTA units, the "free" BTAs are captured into the interior of the SCPN in water as evidenced by fluorescence studies. To illustrate that function can be readily introduced using a modular approach, l-proline-based BTAs are incorporated to procure a catalytically active SCPN in water. The aldol reaction between p-nitrobenzaldehyde and cyclohexanone shows good conversions at low catalyst loadings and substrate concentrations, and high stereoselectivities are obtained (de = 91% and ee = 98%).

Tripodal exTTF-CTV hosts for fullerenes.

A receptor for fullerenes featuring three exTTF units linked to a CTV scaffold is described. The exTTF-CTV host forms remarkably stable complexes with both C(60) (log K(a) = 5.3 +/- 0.2) and C(70) (log K(a) = 6.3 +/- 0.6). Light-induced ESR spectra demonstrate that intracomplex PET processes take place in solution.

Preferential separation of fullerene[84] from fullerene mixtures by encapsulation.

The encapsulation of fullerenes with a cyclotriveratrylene derivative, capable to self assemble into a dimer by means of three strong 4-ureidopyrimidinone quadruple hydrogen bonds is described. The system shows preference for C84, allowing its easy enrichment directly from fullerene mixtures.

A highly directional fourfold hydrogen-bonding motif for supramolecular structures through self-assembly of fullerodendrimers.

Supramolecular dendrimers resulting from the dimerization of fullerene-functionalized dendrons through a quadruple hydrogen-bonding motif were prepared. The synthetic strategy is based on the esterification of a tert-butoxycarbonyl (Boc)-protected 2-ureido-4-[1H]pyrimidinone precursor possessing an alcohol function with fullerodendrons bearing a carboxylic acid unit at the focal point. Subsequent acidic treatment to cleave the protecting group and reaction of the resulting amine with octylisocyanate affords the targeted compounds. As demonstrated by the results of MALDI-TOF mass spectrometry and 1H NMR spectroscopy, both of the 2-ureido-4-[1H]pyrimidinone derivatives form self-assembled dimers spontaneously through hydrogen-bonding interactions, thus leading to supramolecular structures containing two or ten fullerene moieties.