1,720,986 research outputs found
Novel gel-niosomes formulations as multicomponent systems for transdermal drug delivery
No full textThe percutaneous permeation profiles of sulfadiazine sodium salt, propranolol hydrochloride and tyrosol from novel liquid crystal-niosomes formulations as multicomponent systems, were investigated. The new carriers were prepared from mixture of water/surfactant, AOT or Pluronic L64 as anionic and nonionic surfactants, respectively, in order to obtain lamellar LLC phases. The same surfactants were used to prepare also the vesicular systems (niosomes) that were added to the corresponding gel. The obtained multicomponent drug carrier was characterized by deuterium nuclear magnetic resonance spectroscopy, in order to understand if the introduction of the drug or drug-loaded niosomal suspension, as third component in the formulations, could influence the microstructure of the system and then the drug delivery across the skin. Simple AOT and L64-based niosomal formulations and LLCs phases were then prepared and used as control. Different drugs percutaneous availability was achieved, and the results revealed that the obtained gel-niosomes carriers were affected by the chemical structure of the drugs and by their affinity for the components. As a consequence these systems could be proposed as novel transdermal drug delivery systems, since they were found able to control the percutaneous permeation of small drugs across the skin. (C) 2013 Elsevier B.V. All rights reserved
Micelle Formation and Phase Equilibria in a Water-Trifluoroethanol-Fluorocarbon Surfactant System.
No full textThe soln. behavior of the fluorinated surfactant tetraethylammonium perfluorooctane-sulfonate, PFOS, in water-trifluoroethanol, TFE, mixts. has been investigated by surface tension, elec. conductance, and PGSE (pulsed gradient spin-echo) NMR self-diffusion methods. Addn. of progressive amts. of TFE in the solvent has little influence on the crit. micellar concn., CMC. Conversely, self-diffusion, counterion binding, and the surface pressure at the CMC are significantly affected by added fluoroalkanol. The above effects have been explained in terms of the solvent viscosity, dielec. permittivity, and surface activity, resp. The complete phase behavior of the above system has been drawn, and the phase boundaries were detd. According to the above findings, added surfactant promotes the sepn. of the homogeneous solvent mixt. into two coexisting fluid phases. The obsd. behavior was rationalized on thermodn. grounds
Molecularly Imprinted Polymers Based On Amidic Functional Monomers For Selective Recognition Of Cholesterol In Aqueous Media
No full textThe aim of this work was to investigate the possibility of employing
amidic functional monomers for the preparation of Molecularly
Imprinted Polymers (MIPs) able to bind selectively cholesterol in aqueous
media. For this purpose, Acrylamide and N,N-Dimethylacrylamide were
employed in order to maximize the hydrogen bound forming both in
pre-polymerization complex and in rebinding experiments which were
performed in polar solvents; in particular, an acetonitrile:water (7:3 v/
v) mixture was employed. The so obtained matrices showed a good
binding capacity towards the template molecule, they bound, indeed,
much more cholesterol than the corresponding non-imprinted ones.
Finally, the polymers affinity for cholesterol and its selectivity using two
steroids quite similar to cholesterol such as progesterone and
hydrocortisone. The synthesized materials, showed a good selectivity,
because they recognised less effectively the two analogues
Translational Diffusion and Other Physicochemical Properties of a Bolaform Surfactant in Solution.
No full textSome physicochem. properties were studied for a synthetic amphiphile having 2 azacrown ether groups as polar heads (joined to both ends of a C16 alkyl chain) were studied. According to self-diffusion, viscosity, and surface tension trends (as well as the phase diagram), such an α-ω compd. forms large aggregates (presumably vesicles) and exhibits consolute phenomena. Its behavior can be considered intermediate between that of vesicle-forming lipids and that of nonionic surfactants
Novel PEG-coated niosomes based on bola-surfactant as drug carriers for 5-fluorouracil.
No full textInnovative niosomes made up of α,ω-hexadecyl-bis-(1-aza-18-crown-6) (bola), Span 80® and cholesterol (2:5:2 molar ratio) are proposed as suitable delivery systems for the administration of 5-fluorouracil (5-FU), an antitumoral compound largely used in the treatment of breast cancer. The bola-niosomes, after sonication procedure, showed mean sizes of ~200 nm and a loading capacity of ~40% with respect to the amount of 5-FU added during the preparation. Similar findings were achieved with PEG-coated bola-niosomes (bola, Span 80(R), cholesterol, DSPE-mPEG2000, 2:5:2:0.1 molar ratio respectively). 5-FU-loaded PEG-coated and uncoated bola-niosomes were tested on MCF-7 and T47D cells. Both bola-niosome formulations provided an increase in the cytotoxic effect with respect to the free drug. Confocal laser scanning microscopy studies were carried out to evaluate both the extent and the time-dependent bola-niosome-cell interaction. In vivo experiments on MCF-7 xenograft tumor SCID mice models showed a more effective antitumoral activity of the PEGylated niosomal 5-FU at a concentration ten times lower (8 mg/kg) than that of the free solution of the drug (80 mg/kg) after a treatment of 30 days
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Niosomes from alfa,omega-trioxyethylene-bis(sodium2-dodecyloxy-propylene sulfonate): Preparation and characterization.
No full textThe synthesis and characterisation of new surfactants with peculiar physical-chemical properties are amongst the most promising and expanding issues in pharmacological colloid science. The most used vesicular carriers are liposomes prepared from a wide variety of natural and synthetic phospholipids, but several ionic and non-ionic amphiphiles have been used to form multilamellar and/or unilamellar vesicles. In the present study the synthesis of alpha,omega-trioxyethylene-bis(sodium 2-dodecyloxy-propylenesulfonate), an anionic Gemini surfactant, and its ability to form niosomes are elucidated. The compound forms vesicles with and without added cholesterol. The vesicular systems were characterized by size, shape and drug entrapment efficiency. The compounds to be incorporated are P-carotene and ferulic acid, as antioxidants, acetyl salicylic acid, as FANS, and the antineoplastic 5-flurouracil, widely used in dermatological disorders. The results of this study show that et,w-trioxyethylene-bis(sodium 2-dodecyloxy-propylenesulfonate) can be used for the preparation of niosomes entrapping lypophilic, amphiphilic or hydrophilic substances. These niosomes may be promising candidates as percutaneous carriers for the aforementioned drugs
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