Editorial

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Vesicles prepared with the complex salts dioctadecyldimethylammonium polyacrylates

AbstractThe effect of a polymeric counterion on the thermotropic behavior of sonicated vesicles formed by complex salts in aqueous solution and with decanol (C10OH) and tetradecanol (C14OH) was investigated. The complex salts were prepared with dioctadecyldimethylammonium bromide (DODAB) and polyacrylic acids (PAA, containing 30 or 6000 repeating units), being referred to as DODAPA30 and DODAPA6000. Vesicles containing polymeric counterions presented higher contents of multilamellar vesicles that were dependent on the complex salt concentration and on the counterion chain length. For comparison, studies were performed with DODAAc, with the counterion acetate, resulting in the formation of mostly unilamellar vesicles, as expected due greater dissociation, leading to greater electrical repulsion between bilayers. Mixtures of these complex salts and DODAX (where X=acetate or bromide) were also investigated with respect to their vesicles thermotropic behavior and size. This study opens the possibility of applying the methodology of direct complex salt preparation (as opposed to mixing the surfactant and polymeric components) to produce vesicles with controlled composition and properties

Structural parameters of lamellar phases formed by the self-assembly of dialkyldimethylammonium bromides in aqueous solution

Phase behavior of didodecyl and dioctadecydimethylammonium bromide (DDAB and DODAB) in water was studied using X-ray techniques, differential scanning calorimetry and deuterium nuclear magnetic resonance measurements. Both surfactants self-assemble into lamellar liquid crystalline, either Lα (fluid) and Lβ (gel), phases. The gel-to-fluid phase transition temperature (Tm) in DDAB lamellae was found to be higher than that observed for its vesicles, due to the formation of a stabilized gel phase. In addition, the lamellar phases formed by both amphiphiles differ in their swelling degree and bilayer thickness. DODAB in water formed rather thin bilayers, if compared with the length of the tails, suggesting effective chain interdigitation. These bilayers also presented higher swelling degree than those formed by the shorter-chain homologue DDAB. We propose that these structural properties are strongly influenced by the electrostatic repulsive forces acting on the system272392401CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQSem informaçã

New year, new challenges!

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Deformacja wzdłużna stentu uwalniającego lek Synergy w trakcie wyjmowania balonu tnącego

Contemporary stent platforms have reduced strut thickness and fewer connectors. This improves deliverability and conformability, at the expense of reduction in strength. Recently longitudinal shortening has been reported, often associated with adjunctive devices after stent deployment. We present an unusual, impressive case of longitudinal shortening of a previously implanted Synergy stent (Boston Scientific, MA USA), within the proximal left anterior descending artery (LAD). The patient subsequently represented with restenosis of a further stent in the mid LAD. On withdrawal of a Flextome cutting balloon catheter (Boston Scientific), this device snared and dramatically shortened the Synergy. This was successfully treated with progressive dilatation using a series of enlarging balloons and subsequent implantation of another stent (Xience Xpedition, Abbott, CA USA). This case illustrates, that despite having additional connectors to enhance longitudinal strength, Synergy is not immune from compression. Furthermore, it is imperative, that stents are sized and post-dilated appropriately to ensure complete expansion.Rusztowania nowoczesnych stentów cechują się zmniejszoną grubością rozpórek i mniejszą liczbą łączników. To powoduje, że łatwiej je wprowadzić do naczynia i odpowiednio dopasować, jednak zmniejsza ich wytrzymałość. W ostatnim czasie opisywano wiele przypadków skrócenia stentu, często związanych ze stosowaniem dodatkowych narzędzi po implantacji stentu. W niniejszej pracy przedstawiono rzadki, ciekawy przypadek skrócenia wszczepionego wcześniej stenu Synergy (BostonScientific, USA), znajdującego się w proksymalnym odcinku gałęzi międzykomorowej przedniej (LAD). W następstwieu chorego wystąpiła restenoza w dalszej części stentu w środkowym odcinku LAD. W trakcie wyjmowania cewnika z balonem tnącym Flextome (Boston Scientific) urządzenie zaczepiło o stent Synergy i spowodowało jego znaczne skrócenie. Udało się poprawić drożność naczynia przez stopniowe rozszerzanie stenu za pomocą coraz większych balonów oraz wszczepienia kolejnego stentu (Xience Xpedition, Abbott, USA). Opisany przypadek ukazuje, że mimo zastosowania dodatkowych łączników służących wzmocnieniu wytrzymałości stentSynergy nie jest odporny na kompresję. Ponadto należy się zawsze upewnić, że stent został odpowiednio dobrany podwzględem rozmiaru i odpowiednio rozszerzony, aby zapewnić jego całkowite rozprężenie

Template-Free Preparation of Thermoresponsive Mag-netic Cilia Compatible with Biological Conditions

Bio-inspired materials are commonly used in the development of functional devices. The fabrication of artificial cilia mimicking the biological functions has emerged as a promising strategy for fluid manipulation in miniaturized systems. In this study, we propose a different physicochemical insight for the preparation of magnetic cilia based on the temperature-triggered reversible assembly of coated iron oxide nanoparticles in a bio-compatible template-free approach. The length of the prepared cilia could be tuned between 10 and 100 microns reaching aspect ratios up to 100 in a very dense array of flexible structures with persistence lengths around 8 microns. Magnetic actuation of the cilia revealed robust structures (over several hours of actuation) with a wide range of bending amplitudes resulting from high susceptibility of the filaments. The results demonstrate that the proposed strategy is an efficient and versatile alternative for templated fabrication methods and producing cilia with remarkable characteristics and dimensions within the template-free approaches.Comment: 15 pages 5 figure

Analysis of the structure-function relationship of alpha amylase complexed with polyacrylic acid

Alpha-amylase is frequently used in technologies that require its immobilization, stabilization or encapsulation. Polyacrylic acid is a very suitable polymer for these purposes because it can bind to enzymes and then be released under certain conditions without altering the functional capacity of enzymes. The consequences produced by polyacrylic acid on alpha-amylase structure and function have been investigated through various techniques. Calorimetric measurements allowed examining the nature of the binding reaction, stoichiometry and affinity, while spectroscopic techniques provided additional information about functional and structural perturbations of the enzyme. Isothermal titration calorimetry (ITC) revealed a mixed interaction and a binding model with a large number of molecules of protein per molecule of polyacrylic acid. One the one hand circular dichroism (CD) spectroscopy showed that alpha-amylase loses its secondary structure in the presence of increasing concentrations of polyacrylic acid, while it is stabilized by the polyelectrolyte at low pH. On the other hand, fluorescence spectra revealed that the three-dimensional enzyme structure was not affected in the microenvironment of tryptophan residues. Differential scanning calorimetry (DSC) thermograms showed that only one domain of alpha-amylase is affected in its conformational stability by the polymer. The unfolding process proved to be partially reversible. Finally, the enzyme retained more than 90 % of its catalytic activity even in excess of the polymer.Fil: Porfiri, María Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Investigación en Funcionalidad y Tecnología de Alimentos; ArgentinaFil: Melnichuk, Natasha. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Procesos Biotecnológicos y Químicos Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Procesos Biotecnológicos y Químicos Rosario; ArgentinaFil: Braia, Mauricio Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Procesos Biotecnológicos y Químicos Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Procesos Biotecnológicos y Químicos Rosario; ArgentinaFil: Brinatti, César. Universidade Estadual Do Campinas. Instituto de Química.; BrasilFil: Loh, Watson. Universidade Estadual Do Campinas. Instituto de Química.; BrasilFil: Romanini, Diana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Procesos Biotecnológicos y Químicos Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Procesos Biotecnológicos y Químicos Rosario; Argentin

Vesicle-micelle transition in aqueous mixtures of the cationic dioctadecyldimethylammonium and octadecyltrimethylammonium bromide surfactants

The vesicle-micelle transition in aqueous mixtures of dioctadecyldimethylammonium and octadecyltrimethylammonium bromide (DODAB and C18TAB) cationic surfactants, having respectively double and single chain, was investigated by differential scanning calorimetry (DSC), steady state fluorescence, dynamic light scattering (DLS) and surface tension. The experiments performed at constant up to 1.0 mM total surfactant concentration reveal that these homologue surfactants mix together to form either mixed vesicles and/or micelles, or both of these structures in equilibrium, depending on the relative amount of the surfactants. The main transition melting temperature Tm of the mixed DODAB-C18TAB vesicles is larger than that for the neat DODAB in water owing to the incorporation of C18TAB in the vesicle bilayer, however, little amount of C18TAB having a minor effect on the Tm of DODAB. The surface tension decreases sigmoidally with C18TAB concentration and the inflection point lies around xDODAB ≈ 0.4, indicating the onset of micelle formation owing to saturation of DODAB vesicles by C18TAB molecules and formation of vesicle structures. At low C18TAB concentrations When xDODAB > 0.5 C18TAB molecules are mainly solubilized by the vesicles bilayers, while at high C18TAB concentrations but when xDODAB < 0.25 micelles are dominant. Fluorescence data of the Nile Red probe incorporated in the system at different surfactant molar fractions indicate the formation of micelle and vesicle structures. These structures have apparent hydrodynamic radius RH of about 180 and 500-800 nm, respectively, as obtained by DLS measurements.Fundação para a Ciência e a Tecnologia (FCT

Respiratory illness in a piggery associated with the first identified outbreak of swine influenza in Australia: Assessing the risk to human health and zoonotic potential

Australia was previously believed to be free of enzootic swine influenza viruses due strict quarantine practices and use of biosecure breeding facilities. The first proven Australian outbreak of swine influenza occurred in Western Australian in 2012, revealing an unrecognized zoonotic risk, and a potential future pandemic threat. A public health investigation was undertaken to determine whether zoonotic infections had occurred and to reduce the risk of further transmission between humans and swine. A program of monitoring, testing, treatment, and vaccination was commenced, and a serosurvey of workers was also undertaken. No acute infections with the swine influenza viruses were detected. Serosurvey results were difficult to interpret due to previous influenza infections and past and current vaccinations. However, several workers had elevated haemagglutination inhibition (HI) antibody levels to the swine influenza viruses that could not be attributed to vaccination or infection with contemporaneous seasonal influenza A viruses. However, we lacked a suitable control population, so this was inconclusive. The experience was valuable in developing better protocols for managing outbreaks at the human&amp;ndash;animal interface. Strict adherence to biosecurity practices, and ongoing monitoring of swine and their human contacts is important to mitigate pandemic risk. Strain specific serological assays would greatly assist in identifying zoonotic transmission

Chitosan/virgin-coconut-oil-based system enriched with cubosomes: a 3D drug-delivery approach

Emulsion-based systems that combine natural polymers with vegetable oils have been identified as a promising research avenue for developing structures with potential for biomedical applications. Herein, chitosan (CHT), a natural polymer, and virgin coconut oil (VCO), a resource obtained from coconut kernels, were combined to create an emulsion system. Phytantriol-based cubosomes encapsulating sodium diclofenac, an anti-inflammatory drug, were further dispersed into CHT/VCO- based emulsion. Then, the emulsions were frozen and freeze-dried to produce scaffolds. The scaffolds had a porous structure ranging from 20.4 to 73.4 µm, a high swelling ability (up to 900%) in PBS, and adequate stiffness, notably in the presence of cubosomes. Moreover, a well-sustained release of the entrapped diclofenac in the cubosomes into the CHT/VCO-based system, with an accumulated release of 45 ± 2%, was confirmed in PBS, compared to free diclofenac dispersed (80 ± 4%) into CHT/VCO-based structures. Overall, the present approach opens up new avenues for designing porous biomaterials for drug delivery through a sustainable pathway.The authors especially acknowledge the financial support from the Portuguese FCT (grants CEECIND/01306/2018, SFRH/BPD/93697/2013, and SFRH/BPD/85790/2012). This work was also financially supported by the FCT R&D&I project, with reference PTDC/BII-BIO/31570/2017, and the R&D&I Structured Projects, with reference NORTE-01-0145-FDER-000021. We also acknowledge the financial support from São Paulo Research Foundation (FAPESP) in Brasil through projects 2015/25406-5 and 2021/12071-6, and for the postdoctoral grant to D.G.V., 2019/12665-3. The project 2018/08045-7 is part of a bilateral agreement between FAPESP and the FCT (Portugal), involving the project Nature4Health