Análisis espectroscópico del precipitado formado de la mezcla de Hipoclorito de Sodio y Clorhexidina . Estudio In Vitro . Parte II

l objetivo de este estudio fue analizar el precipitado formado por la interacción de dos disoluciones acuosas: una de hipoclorito de sodio al 5.25% y otra de gluconato de clorhexidina al 2%, por medio de cromatografía de capa fina (TLC) y un análisis detallado de espectroscopia de resonancia magnética nuclear (RMN-¹H a 600 MHz y RMN-¹³C a 100 MHz) en una y dos dimensiones. Para esto, se establecieron 3 grupos de estudio: el Grupo A correspondiente a gluconato puro de clorhexidina que fue liofilizado y secado al vacío, el Grupo B: los precipitados obtenidos al combinar 2 ml de la disolución de gluconato de clorhexidina con 2 ml de la disolución de hipoclorito de sodio y el Grupo C, una muestra comercial de PCA (4-Cloroanilina 98%,). El sólido correspondiente al grupo B, fue lavado, centrifugado y seco en estufa de vacío sin calentamiento por más de 72 horas. Una vez seco, se corrieron placas de capa fina (TLC) en diversas mezclas de elución, y se encontró que el precipitado consistía de una mezcla compleja de sustancias similares a la clorhexidina y que no poseía PCA. Los análisis de espectroscopia de resonancia magnética nuclear mostraron que la señal del carbono base del grupo amino de la PCA, a δ/146.5 ppm (grupo C), no se encontraba en el espectro de ¹³C de las muestras del grupo B lo que implica, la ausencia de PCA en la muestra B. El análisis del grupo B por medio de la misma técnica, mostró una mezcla compleja de señales que corresponden probablemente, a estructuras similares a la clorhexidina y a potenciales derivados aromáticos con una estructura similar a esta, nuevamente, no se encuentran evidencias de PCA.

he aim of this study was to analyze the precipitate formed by the mixture of 5,25% sodium hypochlorite (NaOCl) and 2% chlorhexidine (CHX) through thin layer chromatography and nuclear magnetic resonance spectroscopy (RMN-¹H, 600 MHz and RMN-¹³C to 100 MHz) 1D and 2D spectra. Thus, the following groups were established: Group A corresponds to a pure freeze-dried chlorhexidine gluconate , Group B made-up by a combination of 2ml of chlorhexidine 2% and sodium hypochlorite 5.25% and Group C was a commercial sample of PCA (4-Chloroaniline 98%). The samples of group B were rinsed with distillated water and spinned during 15 minutes at 25°C, the supernatant was eliminated by vacuum and vacuum chamber for 72 hours without heating. Finally, the solid was grinded and dried in vacuum chamber for 24 hours without heating. Thin layer chromatography, shows that sample B were composed by more than one chemical substance and Chlorexidine, the RMN-¹³C showed that the signal of the amino group characteristic of PCA appears down field (δ/146.5 ppm) in C group, meanwhile in group B appears up field (δ/129ppm), which demonstrates the absence of PCA during the process. The analysis of Group B by RMN-¹³C results also, in different signals of low intensity that correspond to similar structures to chlorhexidine and potential aromatics derivatives with similar characteristics structures to chlorhexidine.

On the self-assembly of a tryptophan labeled deoxycholic acid.

Self-assembly of peptides and bile acids has been widely investigated because of their biological role and their potential as a tool for the preparation of nanostructured biomaterials. We herein report both the synthesis and the self-association behavior of a compound that combines the aggregation properties of bile acid- and amino acid-based molecules. The derivative has been prepared by introducing a L-tryptophan residue into the C-3 position of the deoxycholic acid skeleton and resulted in an amphoteric fluorescent labeled bile acid that shows a pH-dependent self-assembly. Under alkaline conditions it assembles into 28 nm diameter tubules, thus showing a completely different behavior compared to the precursor bile acid, which forms micelles under similar conditions. Upon heating the tubules break and turn into micelles, leading to an increase in the exposure to water of the tryptophan residue. On the other hand, in acidic solutions it aggregates into elongated micelles that further self-assemble forming a gel network, when an electrolyte is added.

catena-Poly[[[di-aqua-bis-[1,2-bis-(pyridin-4-yl)diazene]copper(II)]-µ-1,2-bis-(pyridin-4-yl)diazene] bis-(perchlorate)].

In the title compound, {[Cu(C10H8N4)3(H2O)2](ClO4)2} n , the coordination environment of the cationic Cu(II) atom is distorted octa-hedral, formed by pairs of symmetry-equivalent 1,2-bis-(pyridin-4-yl)diazene ligands, bridging 1,2-bis-(pyridin-4-yl)diazene ligands and two non-equivalent water mol-ecules. The 1,2-bis-(pyridin-4-yl)diazene mol-ecules form polymeric chains parallel to [-101] via azo bonds which are situated about inversion centres. Since the Cu(II) atom is situated on a twofold rotation axis, the monomeric unit has point symmetry 2. The perchlorate anions are disordered in a 0.536 (9):0.464 (9) ratio and are acceptors of water H atoms in medium-strong O-H⋯O hydrogen bonds with graph set R 4 (4)(12). The water mol-ecules, which are coordinated to the Cu(II) atom and are hydrogen-bonded to the perchlorate anions, form columns parallel to [010]. A π-π inter-action [centroid-centroid distance = 3.913 (2) Å] occurs between pyridine rings, and weak C-H⋯O inter-actions also occur.

Drug-loaded nanoparticles and supramolecular nanotubes formed from a volatile microemulsion with bile salt derivatives.

The main objective of this study was to form nanoparticles of a model hydrophobic drug, celecoxib, from a volatile microemulsion stabilized by a bile salt derivative. Nanoparticles were obtained by conversion of the microemulsion nanodroplets with the dissolved drug into solid nanometric particles. The use of bile salt derivatives as the surfactants for the formation of a microemulsion enabled significantly higher loading of the drug in both the microemulsion and nanoparticles, compared with the native bile salt. In addition, superior stability of the particles was achieved with the bile salt derivatives, and drug crystallization was inhibited. Interestingly, differences in particle stability and crystallization inhibition were observed between two bile salt derivatives differing only by one hydroxyl group on the bile salt backbone, indicating the delicate balance of interactions in the system. For one of the derivatives, upon dispersion of the nanoparticles in water, they spontaneously arranged into well-defined elongated nanometric tubules as detected and attested by cryo-TEM. It was found that the drug present in nanoparticles induces formation of the nanotubes.

New lamellar structure formed by an adamantyl derivative of cholic acid.

The self-aggregation of the sodium salt of a new adamantyl amide of the 3beta-amino derivative of cholic acid (Na-AdC) in aqueous solution has been investigated by surface tension, dynamic light scattering, fluorescence, small-angle X-ray scattering (SAXS), and transmission electron microscopy (TEM) measurements. These last two techniques suggest that a lamellar phase, consisting of charged bilayers of Na-AdC separated by solvent and periodically stacked, is formed in aqueous solution. The structure of the bilayer is inferred from the resolution of the crystal of the compound in its acid form. The adamantyl moieties, which are mutually interlocked, reside in the central region of the bilayer, and the carboxylic groups are directed toward the hydrophilic region. The structure is open enough to allow water molecules to interact with a fluorescence probe located at the central hydrophobic region.

Thermodynamics of formation of host-guest supramolecular polymers.

The interactions between three beta-cyclodextrin hosts (having 1-3 binding sites) and two adamantyl guests (having 1-2 binding sites) have been studied by ITC, ROESY, static and dynamic light scattering (SLS and DLS), and AFM and TEM techniques. The enthalpy and free energy values (determined from ITC experiments) evidence that the single interaction between one binding site of the guest and one binding site of the host is independent of the number of binding sites of the interacting species. The average values are deltaH degrees = -26.6 +/- 2.3 kJ mol(-1) and deltaG degrees = -30.4 +/- 3.2 kJ mol(-1), indicating that the process is mainly enthalpy driven. In all cases, the experimental molar ratio (from ITC experiments) agrees with the expected one from the number of binding sites of both the host and guest. The formation of polymer-like entities was demonstrated by SLS, DLS, AFM, and TEM measurements. The structure of polymers is linear when both the host and the guest are ditopic entities and dendritic (or Cayley tree type) when the host and the guest have three and two binding sites, respectively.