Crina Saviuc

Hybrid magnetite nanoparticles/Rosmarinus officinalis essential oil nanobiosystem with antibiofilm activity

Biofilms formed by fungal organisms are associated with drastically enhanced resistance against most antimicrobial agents, contributing to the persistence of the fungi despite antifungal therapy. The purpose of this study is to combine the unique properties of nanoparticles with the antimicrobial activity of the Rosmarinus officinalis essential oil in order to obtain a nanobiosystem that could be pelliculised on the surface of catheter pieces, in order to obtain an improved resistance to microbial colonization and biofilm development by Candida albicans and C. tropicalis clinical strains. The R. officinalis essential oils were extracted in a Neo-Clevenger type apparatus, and its chemical composition was settled by GC-MS analysis. Functionalized magnetite nanoparticles of up to 20 nm size had been synthesized by precipitation method adapted for microwave conditions, with oleic acid as surfactant. The catheter pieces were coated with suspended core/shell nanoparticles (Fe3O4/oleic acid:CHCl3), by applying a magnetic field on nanofluid, while the CHCl3 diluted essential oil was applied by adsorption in a secondary covering treatment. The fungal adherence ability was investigated in six multiwell plates, in which there have been placed catheters pieces with and without hybrid nanoparticles/essential oil nanobiosystem pellicle, by using culture-based methods and confocal laser scanning microscopy (CLSM). The R. officinalis essential oil coated nanoparticles strongly inhibited the adherence ability and biofilm development of the C. albicans and C. tropicalis tested strains to the catheter surface, as shown by viable cell counts and CLSM examination. Due to the important implications of Candida spp. in human pathogenesis, especially in prosthetic devices related infections and the emergence of antifungal tolerance/resistance, using the new core/shell/coated shell based on essential oil of R. officinalis to inhibit the fungal adherence could be of a great interest for the biomedical field, opening new directions for the design of film-coated surfaces with antibiofilm properties.

Inhibitory Activity of

Undesired biofilm development is a major concern in many areas, especially in the medical field. The purpose of the present study was to comparatively investigate the antibiofilm efficacy of usnic acid, in soluble versus nanofluid formulation, in order to highlight the potential use of Fe3O4/oleic acid (FeOA) nanofluid as potential controlled release vehicle of this antibiofilm agent. The (+) -UA loaded into nanofluid exhibited an improved antibiofilm effect on S. aureus biofilm formation, revealed by the drastic decrease of the viable cell counts as well as by confocal laser scanning microscopy images. Our results demonstrate that FeOA nanoparticles could be used as successful coating agents for obtaining antibiofilm pellicles on different medical devices, opening a new perspective for obtaining new antimicrobial and antibiofilm surfaces, based on hybrid functionalized nanostructured biomaterials.

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The purpose of this work was to investigate the potential of functionalized magnetite nanoparticles to improve the antibiofilm properties of textile dressing, tested in vitro against monospecific Candida albicans biofilms. Functionalized magnetite (Fe3O4/C18), with an average size not exceeding 20 nm, has been synthesized by precipitation of ferric and ferrous salts in aqueous solution of oleic acid (C18) and NaOH. Transmission electron microscopy, X-ray diffraction analysis, and differential thermal analysis coupled with thermo gravimetric analysis were used as characterization methods for the synthesized Fe3O4/C18. Scanning electron microscopy was used to study the architecture of the fungal biofilm developed on the functionalized textile dressing samples and culture-based methods for the quantitative assay of the biofilm-embedded yeast cells. The optimized textile dressing samples proved to be more resistant to C. albicans colonization, as compared to the uncoated ones; these functionalized surfaces-based approaches are very useful in the prevention of wound microbial contamination and subsequent biofilm development on viable tissues or implanted devices.

/Oleic Acid/Usnic Acid—Core/Shell/Extra-Shell Nanofluid on S. aureus Biofilm Development

During the present study, we have evaluated magnetic chitosan as a potential drug delivery device, by specifically determining if chitosan could elute antibiotics in an active form that would be efficacious in inhibiting Staphylococcus aureus and Escherichia coli growth. We have demonstrated that the incorporation of cephalosporins of second, third and fourth generation into magnetic chitosan microspheres can possibly lead to an improved delivery of antibiotics in active forms, probably due to the inherent properties of chitosan.

Magnetite nanoparticles for functionalized textile dressing to prevent fungal biofilms development

The aim of the present study was to demonstrate that Fe3O4/oleic acid core/shell nanostructures could be used as systems for stabilizing the Eugenia carryophyllata essential oil (EO) on catheter surface pellicles, in order to improve their resistance to fungal colonization. EO microwave assisted extraction was performed in a Neo-Clevenger (related) device and its chemical composition was settled by GC-MS analysis. Fe3O4/oleic acid-core/shell nanoparticles (NP) were obtained by a precipitation method under microwave condition. High resolution transmission electron microscopy (HR-TEM) was used as a primary characterization method. The NPs were processed to achieve a core/shell/EO coated-shell nanosystem further used for coating the inner surface of central venous catheter samples. The tested fungal strains have been recently isolated from different clinical specimens. The biofilm architecture was assessed by confocal laser scanning microscopy (CLSM). Our results claim the usage of hybrid nanomaterial (core/shell/coated-shell) for the stabilization of E. carryophyllata EO, which prevented or inhibited the fungal biofilm development on the functionalized catheter, highlighting the opportunity of using these nanosystems to obtain improved, anti-biofilm coatings for biomedical applications.

Improved antibacterial activity of cephalosporins loaded in magnetic chitosan microspheres

A family of distinct ZnO morphologies - hollow, compartmented, core-shell and full solid ZnO spheres, dispersed or interconnected - is obtained by a simple hydrothermal route, in the presence of the starch biopolymer. The zinc-carbonaceous precursors were characterized by infrared spectroscopy, thermal analysis and scanning electron microscopy, while the ZnO spheres, obtained after the thermal processing, were investigated by X-ray diffraction, Raman spectroscopy, scanning electron microscopy, UV-VIS spectroscopy, photoluminescence measurements, antimicrobial, anti-biofilm and flow cytometry tests. The formation mechanism proposed for this versatile synthesis route is based on the gelling ability of amylose, one of the starch template constituents, responsible for the effective embedding of zinc cations into starch prior to its hydrothermal carbonization. The simple variation of the raw materials concentration dictates the type of ZnO spheres. The micro-sized ZnO spheres exhibit high antibacterial and anti-biofilm activity against Gram-positive (Staphylococcus aureus, Bacillus subtilis) and Gram-negative (Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa) reference and methicillin resistant clinical strains especially for Gram-negative biofilms (P. aeruginosa), demonstrating great potential for new ZnO anti-biofilm formulations.

Hybrid Nanomaterial for Stabilizing the Antibiofilm Activity of Eugenia carryophyllata Essential Oil

The purpose of this study was to design a new nanosystem for catheter surface functionalization with an improved resistance to Staphylococcus aureus ATCC 25923 and Pseudomonas aeruginosa ATCC 27853 colonization and subsequent biofilm development. New 2-((4-ethylphenoxy)methyl)-N-(substituted-phenylcarbamothioyl)-benzamides were synthesized and used for coating a core/shell nanostructure. Their chemical structures were elucidated by NMR, IR and elemental analysis, being in agreement with the proposed ones. Fe3O4/C12 of up to 5 nm size had been synthesized with lauric acid as a coating agent and characterized by XRD, FT-IR, TGA, TEM and biological assays. The catheter pieces were coated with the fabricated nanofluid in magnetic field. The microbial adherence ability was investigated in 6 multiwell plates by using culture based methods and Scanning Electron Microscopy (SEM). The nanoparticles coated with the obtained compounds 1a–c inhibited the adherence and biofilm development ability of the S. aureus and P. aeruginosa tested strains on the catheter functionalized surface, as shown by the reduction of viable cell counts and SEM examination of the biofilm architecture. Using the novel core/shell/adsorption-shell to inhibit the microbial adherence could be of a great interest for the biomedical field, opening new directions for the design of film-coated surfaces with improved anti-biofilm properties.

Tunable ZnO spheres with high anti-biofilm and antibacterial activity via a simple green hydrothermal route.

The antibacterial and anti-inflammatory potential of natural, plant-derived compounds has been reported in many studies. Emerging evidence indicates that plant-derived essential oils and/or their major compounds may represent a plausible alternative treatment for acne, a prevalent skin disorder in both adolescent and adult populations. Therefore, the purpose of this study was to develop and subsequently analyze the antimicrobial activity of a new multi-agent, synergic formulation based on plant-derived antimicrobial compounds (i.e., eugenol, β-pinene, eucalyptol, and limonene) and anti-inflammatory agents for potential use in the topical treatment of acne and other skin infections. The optimal antimicrobial combinations selected in this study were eugenol/β-pinene/salicylic acid and eugenol/β-pinene/2-phenoxyethanol/potassium sorbate. The possible mechanisms of action revealed by flow cytometry were cellular permeabilization and inhibition of efflux pumps activity induced by concentrations corresponding to sub-minimal inhibitory (sub-MIC) values. The most active antimicrobial combination represented by salycilic acid/eugenol/β-pinene/2-phenoxyethanol/potassium sorbate was included in a cream base, which demonstrated thermodynamic stability and optimum microbiological characteristics.

Optimized Anti-pathogenic Agents Based on Core/Shell Nanostructures and 2-((4-Ethylphenoxy)ethyl)-N-(substituted- phenylcarbamothioyl)-benzamides

MAPLE (matrix-assisted pulsed laser evaporation) technique revealed a significant relevance in the deposition of bioactive nanostructures on different surfaces for the prevention and/or treatment of microbial infections associated with medical devices. Recent research progress highlights the development of two new directions for biomedical applications of magnetite nanoparticles: the antimicrobial therapy and microbial virulence and biofilm modulation. The aim of this chapter is to highlight the usefulness of functionalized magnetite nanoparticles as efficient anti-infective agents. In this respect, different type of nanocomposites based on hydrophilic/hydrophobic polymers and iron oxide nanostructures combined with natural and synthetic therapeutic agents are discussed. We offer a wide perspective regarding their synthesis, characterization, biocompatibility, and the ability to modulate the microbial attachment and biofilms development on different type of prosthetic devices or metal implants. All reported data demonstrate that magnetite-based bioactive coatings significantly inhibit the microbial colonization on the coated medical surfaces, features that together with their high in vivo viability recommend these type of thin coatings for the development of anti-infective surfaces for biomedical applications.

Development and Sequential Analysis of a New Multi-Agent, Anti-Acne Formulation Based on Plant-Derived Antimicrobial and Anti-Inflammatory Compounds.

Botanical pesticides are vegetal extracts or compounds used for preventing, destroying, or controlling different types of pest. Due to their reduced toxicity and side effects as compared to the chemical ones, these substances could represent a promising alternative for the development of new biocontrol agents, both efficient, and also fulfilling the safety requirements for food security and human health. The purpose of this chapter is to give an overview over the biopesticides of vegetal origin (plant extracts and essential oils) with virucidal, bactericidal, and fungicidal activity.