水介质中药物-AOT混合物的温度依赖的混合胶束化行为(英文)

The mixed micellization behavior of an amphiphilic antidepressant drug amitriptyline hydrochloride(AMT)in the presence of the conventional anionic surfactant sodium bis(2-ethylhexyl)sulfosuccinate(AOT)was studied at five different temperatures and compositions by the conductometric technique.The critical micelle concentration(cmc)and critical micelle concentration at the ideal state(cmcid)values show mixed micelle formation between the components(i.e.,drug and AOT).The micellar mole fractions of the AOT(X1)values calculated using the Rubingh,Motomura,and Rodenas models show a higher contribution of AOT in the mixed micelles.The interaction parameter(β)is negative at all temperatures and the compositions show attractive interactions between the components.The activity coefficients(f1and f2)calculated using the different proposed models are always less than unity indicating non-ideality in the systems.TheΔGmΘ values were found to be negative for all the binary mixed systems.However,ΔHmΘ values for the pure drug as well as the drug-AOT mixed systems are negative at lower temperatures(293.15-303.15 K)and positive at higher temperatures(308.15 K and above).TheΔSmΘ values are positive at all temperatures but their magnitude was higher at T=308.15 K and above.The excess free energy of mixing(ΔGex)determined using the different proposed models also explains the stability of the mixed micelles compared to the pure drug(AMT)and surfactant micelles.     

Spectral Mapping Theorem for Fractional Powers of Linear Relations

In this paper, we give the fractional powers version of spectral mapping theorems for various essential spectra of non-negative linear operators and non-negative linear relations.     

Phosphonium-mediated cyclization of N-(2-aminophenyl)thioureas: efficient synthesis of 2-aminobenzimidazoles

BOP efficiently promoted the phosphonium-mediated cyclization of thioureas, leading to a convenient synthesis of 2-aminobenzimidazoles. Compared to conventional methods, the reactions were complete at room temperature with times ranging from a few minutes to 1 h in near quantitative yields. This method is also applicable to the synthesis of more challenging structures such as 2-akylaminobenzimidazoles and 2-(N-acyl)-aminobenzimidazoles. The methodology described herein represents a mild and efficient route to a variety of 2-aminobenzimidazoles.     

1-C-Alkyl imino-d-xylitol and -l-arabinitol derivatives obtained via nucleophilic addition to pentose-derived N-tert-butanesulfinyl imines: sugar- versus chiral auxiliary-induced stereoselectivity

The stereoselective synthesis of 1-C-alkyl iminosugars in the d-xylo and l-arabino series as potential drugs for the treatment of lysosomal diseases has been achieved. The key step involves nucleophilic addition to pentodialdofuranose-derived imines generated using enantiopure tert-butanesulfinamide. Depending on the pentofuranose configuration and structure, the stereoselectivity of this reaction was found to be controlled either by the sugar moiety or by the stereogenic sulfur center.     

Surface crystallization of rapamycin on stents using a temperature induced process

Metallic drug eluting stents (DES) are usually prepared by coating with a drug-polymer matrix as a rate controlling diffusion barrier. However, coating materials may display numerous problems, thus carrier-free DES are desired, yet releasing drug over long period of time. For this, we are reporting a novel temperature induced (TI) crystallization process for coating rapamycin on stents. Rapamycin crystals with a defined morphology and target drug load were applied from supersaturated solution. This method enables fabrication of controllable and homogeneous crystalline coatings on stent scaffolds and allowing the drug to release for several weeks.     

Monte Carlo modelling for the in vivo lung monitoring of enriched uranium: Results of an international comparison

In order to assess the reliability of Monte Carlo (MC)-based numerical calibration of in vivo counting systems the EURADOS network supported a comparison of MC simulation of well-defined experiments. This action also provided training for the use of voxel phantoms. In vivo measurements of enriched uranium in a thoracic phantom have been carried out and the needed information to simulate these measurements was distributed to 17 participants. About half of the participants managed to simulate the measured counting efficiency without support from the organisers. Following additional support all participants managed to simulate the counting efficiencies within a typical agreement of ±5% with experiment.     

pH-Metric study of gamma-irradiated table sugar for dosimetry purpose

Table sugar has been studied for a long time as a dosimeter in radiation accident and in high-dose dosimetry by using different analytical techniques especially electron paramagnetic resonance (EPR) and optical absorption spectrometry (OA). In this work, we report the results obtained by pH-metry on gamma-irradiated sugar. Table sugar samples were exposed to gamma radiation with doses of 0.1–58 kGy. Aqueous solutions of sugar were prepared with different concentrations ranged from 1% to 60% (w/w). It was found that sugar solutions showed strong decrease of pH up to concentration of 10% (w/w) followed by a slow decrease for the concentrations between 10 and 60% (w/w). Two possible mechanisms are proposed to explain the acidity increasing of the sugar solutions based on the existence of a carbonyl radical induced by gamma irradiation in solid table sugar with an open ring structure. Results for radiation response, post-irradiation change, reading temperature, dose-rate effect and repeatability are presented in this study. The results showed that pH-metric/sugar solution is an adequate high-dose dosimetric system in the dose range of 0.1–10 kGy.     

Mesoporous γ‐Iron Oxide Nanoparticles for Magnetically Triggered Release of Doxorubicin and Hyperthermia Treatment

Mesoporous iron‐oxide nanoparticles (mNPs) were prepared by using a modified nanocasting approach with mesoporous carbon as a hard template. mNPs were first loaded with doxorubicin (Dox), an anticancer drug, and then coated with the thermosensitive polymer Pluronic F108 to prevent the leakage of Dox molecules from the pores that would otherwise occur under physiological conditions. The Dox‐loaded, Pluronic F108‐coated system (Dox@F108‐mNPs) was stable at room temperature and physiological pH and released its Dox cargo slowly under acidic conditions or in a sudden burst with magnetic heating. No significant toxicity was observed in vitro when Dox@F108‐mNPs were incubated with noncancerous cells, a result consistent with the minimal internalization of the particles that occurs with normal cells. On the other hand, the drug‐loaded particles significantly reduced the viability of cervical cancer cells (HeLa, IC₅₀=0.70 μm ), wild‐type ovarian cancer cells (A2780, IC₅₀=0.50 μm ) and Dox‐resistant ovarian cancer cells (A2780/AD, IC₅₀=0.53 μm ). In addition, the treatment of HeLa cells with both Dox@F108‐mNPs and subsequent alternating magnetic‐field‐induced hyperthermia was significantly more effective at reducing cell viability than either Dox or Dox@F108‐mNP treatment alone. Thus, Dox@F108‐mNPs constitute a novel soft/hard hybrid nanocarrier system that is highly stable under physiological conditions, temperature‐responsive, and has chemo‐ and thermotherapeutic modes of action.     

In vivo oral insulin delivery via covalent organic frameworks

With diabetes being the 7th leading cause of death worldwide, overcoming issues limiting the oral administration of insulin is of global significance. The development of imine-linked-covalent organic framework (nCOF) nanoparticles for oral insulin delivery to overcome these delivery barriers is herein reported. A gastro-resistant nCOF was prepared from layered nanosheets with insulin loaded between the nanosheet layers. The insulin-loaded nCOF exhibited insulin protection in digestive fluids in vitro as well as glucose-responsive release, and this hyperglycemia-induced release was confirmed in vivo in diabetic rats without noticeable toxic effects. This is strong evidence that nCOF-based oral insulin delivery systems could replace traditional subcutaneous injections easing insulin therapy.

We report the successful use of a gastro-resistant covalent organic framework for in vivo oral delivery of insulin.     

Squarate complexes of some lanthanide ions in aqueous solution

The squarate complexes of Eu³⁺, Tb³⁺ and Tm³⁺ in aqueous solutions of 0.05M, 0.075M and 0.1M ionic strength are studied using the solvent extraction method. Effects of changes in the ionic strength on the stability constants of the complexes formed are discussed.