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Mihail Kogălniceanu, Romania

Marin L.,Petru Poni Institute of Macromolecular Chemistry | Ailincai D.,Petru Poni Institute of Macromolecular Chemistry | Mares M.,Ion Ionescu Of La Brad University | Paslaru E.,Petru Poni Institute of Macromolecular Chemistry | And 4 more authors.
Carbohydrate Polymers | Year: 2015

The paper reports the preparation of twelve imino-chitosan biopolymer films by acid condensation of the amino groups of chitosan with various aldehydes, in aqueous medium, followed by slow water removal. FTIR spectroscopy has shown drastic conformation changes of chitosan macromolecular chains - from a stiff coil to a straight one, while wide angle X-ray diffraction evidenced a layered morphology of the biopolymer films. Contact angle and surface free energy determination indicated a higher biocompatibility of the new biopolymers as compared to the chitosan parent, while the microbiological screening demonstrated their self-defense properties against common and virulent pathogen agents. It was concluded that the reversibility of imine forming promotes the self-assembling of imino-chitosan biopolymer films into a lamellar morphology and, on the other hand, the slow release of the antimicrobial aldehyde in the microbiological culture. The obtained results demonstrate that chitosan polyamine is a challenging workbench to functional biodynamic materials. © 2014 Elsevier Ltd. All rights reserved. Source

Racles C.,Petru Poni Institute of Macromolecular Chemistry | Racles C.,Technical University Gheorghe Asachi | Mares M.,Ion Ionescu Of La Brad University | Sacarescu L.,Petru Poni Institute of Macromolecular Chemistry
Colloids and Surfaces A: Physicochemical and Engineering Aspects | Year: 2014

The aqueous dissolution of a poorly soluble drug nystatin (Nys) was achieved by a simple, excipient-free procedure using a tromethamol-modified polysiloxane (ST) as surfactant. Long-term stable Nys aqueous formulation was prepared and investigated by different methods, in order to understand the mechanism of drug solubilization. The cryo-TEM analysis revealed the presence of soft vesicles in the Nyst_ST solution. According to TEM measurements, the drug is contained in the hydrophobic layer of the surfactant vesicles. The dynamic light scattering (DLS) measurements on Nys_ST showed a main population around 134. nm having the Zeta potential of 33.3. mV. FT-IR, UV-vis, and thermogravimetric (TG-DTG-DTA) data point toward physical encapsulation, accompanied by a decrease of H-bonding between the drug molecules. The antifungal activity tested in vitro toward four yeast strains was seriously improved compared to the aqueous dispersion of the native drug, although the availability was diminished compared to DMSO solution. © 2013 Elsevier B.V. Source

Marin L.,Petru Poni Institute of Macromolecular Chemistry | Stoica I.,Petru Poni Institute of Macromolecular Chemistry | Mares M.,Ion Ionescu Of La Brad University | Dinu V.,Petru Poni Institute of Macromolecular Chemistry | And 4 more authors.
Journal of Materials Chemistry B | Year: 2013

Vanillin-chitosan biodynamers have been prepared and structure-morphology correlations revealed the pathway of progressive incorporation of the aldehyde onto chitosan backbones. Such dynamic biopolymers or biodynamers, generated from reversibly interacting components, offer the possibility to address the dynamic covalent behaviour of the reversible imine-bond formation/hydrolysis equilibria between vanillin and chitosan polymeric backbones. The reaction takes place with very low conversion in acidic aqueous solutions (7-12%), but the imine bond formation is amazingly improved (∼80%) when the reaction takes place while solution-solid state transition and solid state phase-organization events occur. The chitosan-vanillin biopolymeric films described here present interesting Candida albicans antifungal activity compared with other common bacterial strands, which suggests the implementation of these biocompatible materials as thin layer protecting systems for medical devices. © 2013 The Royal Society of Chemistry. Source

Kolecka A.,Fungal Biodiversity Center | Khayhan K.,Fungal Biodiversity Center | Khayhan K.,University of Phayao | Groenewald M.,Fungal Biodiversity Center | And 9 more authors.
Journal of Clinical Microbiology | Year: 2013

Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) was used for an extensive identification study of arthroconidial yeasts, using 85 reference strains from the CBS-KNAW yeast collection and 134 clinical isolates collected from medical centers in Qatar, Greece, and Romania. The test set included 72 strains of ascomycetous yeasts (Galactomyces, Geotrichum, Saprochaete, and Magnusiomyces spp.) and 147 strains of basidiomycetous yeasts (Trichosporon and Guehomyces spp.). With minimal preparation time, MALDI-TOF MS proved to be an excellent diagnostic tool that provided reliable identification of most (98%) of the tested strains to the species level, with good discriminatory power. The majority of strains were correctly identified at the species level with good scores (>2.0) and seven of the tested strains with log score values between 1.7 and 2.0. The MALDI-TOF MS results obtained were consistent with validated internal transcribed spacer (ITS) and/or large subunit (LSU) ribosomal DNA sequencing results. Expanding the mass spectrum database by increasing the number of reference strains for closely related species, including those of nonclinical origin, should enhance the usefulness of MALDI-TOF MS-based diagnostic analysis of these arthroconidial fungi in medical and other laboratories. Copyright © 2013, American Society for Microbiology. Source

Simionescu B.,Petru Poni Institute of Macromolecular Chemistry | Bordianu I.-E.,Petru Poni Institute of Macromolecular Chemistry | Aflori M.,Petru Poni Institute of Macromolecular Chemistry | Doroftei F.,Petru Poni Institute of Macromolecular Chemistry | And 4 more authors.
Materials Chemistry and Physics | Year: 2012

The paper reports the first study on hierarchical assemblies (nanofibrillar micelles confined within semi-cylindrical shells) with silsesquioxane and quaternary ammonium units obtained through polymer blending intended for antimicrobial/antifungal stone coatings. The formation of hierarchical structures on solid surfaces is due to the multiple intermolecular ionic interactions, intermolecular Van der Waals and hydrophobic interactions acting among the component molecules. Their antimicrobial/antifungal properties toward the Gram-negative bacteria, Escherichia coli, Gram-positive bacteria, Staphylococcus aureus, and Candida albicans fungus were determined in aqueous solution and were found to be strongly dependent of the topographical features of the coating. © 2012 Elsevier B.V. All rights reserved. Source

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