Green stabilization of silver nanoparticles over the surface of biocompatible Fe3O4@CMC for bactericidal applications.

The emergence of antimicrobial resistance in bacteria, especially in agents associated with urinary tract infections (UTIs), has initiated an exciting effort to develop biocompatible nanoparticles to confront their threat. Designing simple, cheap, biocompatible, and efficient nanomaterials as bactericidal agents seems to be a judicious response to this problem. Here, a solvothermal method was hired for the one-pot preparation of the cellulose gum (carboxymethyl cellulose, CMC) magnetic composite to prepare a cost-effective, efficient, and biocompatible support for the plant-based stabilization of the silver NPs. The green stabilization of the Ag NPs is performed using Euphorbia plant extract with high efficiency. Various characterization methods, including FT-IR, XRD, SEM, EDS, TEM, and VSM were used to study the composition and properties of Fe3O4@CMC/AgNPs. The composite shows well integrity and monodispersity with a mean diameter of <300 nm, indicating its potential for bio-related application. The CMC functionalities of the proposed material facilitated the stabilization of the Ag NPs, resulting in their monodispersity and enhanced performance. The manufactured composite was used as an antibacterial agent for the removal of UTIs agents, collected from 200 hospitalized patients with acute coronary syndrome, which showed promising results. This study showed that the concentration of the Ag NPs has a direct relationship with the antibacterial properties of the composite.

Adenosine-Monophosphate-Assisted Homogeneous Silica Coating of Silver Nanoparticles in High Yield.

In this study, we propose a novel approach for the silica coating of silver nanoparticles based on surface modification with adenosine monophosphate (AMP). Upon AMP stabilization, the nanoparticles can be transferred into 2-propanol, promoting the growth of silica on the particle surfaces through the standard Stöber process. The obtained silica shells are uniform and homogeneous, and the method allows a high degree of control over shell thickness while minimizing the presence of uncoated NPs or the negligible presence of core-free silica NPs. In addition, AMP-functionalized AgNPs could be also coated with a mesoporous silica shell using cetyltrimethylammonium chloride (CTAC) as a template. Interestingly, the thickness of the mesoporous silica coating could be tightly adjusted by either the silica precursor concentration or by varying the CTAC concentration while keeping the silica precursor concentration constant. Finally, the influence of the silica coating on the antimicrobial effect of AgNPs was studied on Gram-negative bacteria (R. gelatinosus and E. coli) and under different bacterial growth conditions, shedding light on their potential applications in different biological environments.

Physicochemical and Antibacterial Evaluation of TiO2/CNT Mesoporous Nanomaterials Prepared by High-Pressure Hydrothermal Sol-Gel Method under an Ultrasonic Composite Environment.

TiO2 has attracted significant research interest, principally due to its nontoxicity, high stability, and abundance. Carbon-doped TiO2 can improve light absorption efficiency. In order to prepare high-efficiency photocatalysts, carbon-doped composites were prepared by hydrothermal reaction in a high-pressure reactor, and then TiO2/CNT mesoporous composites were prepared by the sol-gel method in an ultrasonic environment. Characterized by SEM and TEM, the composite materials contained TiO2 nanoparticles as well as CNT. After phase analysis, it was the anatase-doped phase. The following infrared light absorption performance and Escherichia coli bactericidal performance tests showed that it had better infrared and visible light absorption performance than pure TiO2. The TiO2/CNT mesoporous nanomaterials synthesized in this work are possible for clean industrial productions.

Birch Tar Introduced into Polylactide and Its Influence on the Barrier, Thermal, Functional and Biological Properties of the Film Obtained by Industrial Extrusion.

The aim of the study was to evaluate possibility of producing a polylactide film with birch tar by the industrial extrusion method and whether the addition of 10% birch tar can ensure adequate biocidal properties of PLA against pathogenic microorganisms (E. coli, S. aureus, P. aeruginosa, A. tumefaciens, X. campestris, P. brassicacearum, P. corrugate and P. syringae) and fungi (A. niger, A. flavus and A. versicolor) while ensuring beneficial functional properties, such as water vapor, nitrogen, oxygen and carbon dioxide permeability, which are of considerable importance in the packaging industry. The main test methods used were ISO 22196, ISO 846, ISO 2556, ASTM F 1927 and ASTM F 2476-20. The obtained results prove the possibility of extruding polymer films with a biocidal additive, i.e., birch tar, and obtaining favorable properties that qualify the produced film for applications in the packaging industry.

Bactericidal and Fungistatic Properties of LDPE Modified with a Biocide Containing Metal Nanoparticles.

The aim of this study was to ascertain whether the combined action of metal nanoparticles (silver, copper, zinc oxide, iron oxide) would ensure the appropriate biocidal properties oflow-density polyethylene (LDPE) against pathogenic microorganisms. According to the research hypothesis, appropriately selected concentrations of the applied metal nanoparticles allow for a high level of biocidal activity of polymeric materials against both model and pathogenic bacterial strains (Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, Legionella pneumophila, Salmonella enterica subsp. enterica) and fungi (Aspergillus brasiliensis, Saccharomyces cerevisiae, Candida albicans, Penicilium expansum), whilst ensuring the safety of use due to the lack of migration of particles to the surrounding environment. Studies have shown that adding 4% of a biocide containing Ag, Cu, ZnO, and Fe2O3 nanoparticles is the most optimal solution to reduce the number of S. aureus, S. enterica and P. aeruginosa by over 99%. The lowest effectiveness was observed against L. pneumophila bacteria. As for E. coli, a higher biocide content did not significantly increase the antibacterial activity. The results showed a high efficiency of the applied biocide at a concentration of 2% against fungal strains. The high efficiency of the obtained biocidal results was influenced by the uniform dispersion of nanoparticles in the material and their low degree of agglomeration. Furthermore, a slight migration of components to the environment is the basis for further research in the field of the application of the developed materials in industry.

Insight into the impingement of different sodium precursors on structural, biocompatible, and hemostatic properties of bioactive materials.

Bioactive materials play a significant role in biomedical engineering for plethora of applications. To date, there is no evident report on the role of sodium precursors in structural changes towards their acceleration in biocompatibility. This study highlights the impact and role of two different sodium precursors (sodium nitrate and sodium hydroxide) on the structural changes and their potential formulations in biomineralization and biocompatibility. Structural characteristics enunciate the significant crystallization of NaCaPO4, Na2Ca2Si3O9, and Na1.8Ca1.1Si6O14 phases with pertinent Q2 stretching's while using sodium nitrate than sodium hydroxide. XPS spectra authenticate the elevated sodium content while using sodium nitrate as sodium precursor. One-dimensional structures with well faceted morphology and superior alkaline environment preferentially support the biomineralization and bactericidal properties in sodium nitrate-bioglass, was confirmed through structural, morphological, elemental, and antibacterial investigations. Whereas, higher blood and cell-line compatibility with elevated protein adsorption rate is perceived for the bioglass prepared using sodium hydroxide source, and subsequently, higher hemostatic properties are considerably observed with sodium nitrate-bioglass. Higher mechanical stability (ultrasonic measurements) and controlled degradation rate are the stratagems of sodium nitrate to boost the basic criteria of bioactive materials. Hence, it is proposed that sodium nitrate is a highly preferable source to develop bioactive and stable bioglass formulations.

Anti-biofouling microfiltration membranes based on 1-vinyl-3-butylimidazolium chloride grafted PVDF with improved bactericidal properties and vitro biocompatibility.

Polyvinylidene fluoride (PVDF) porous membranes have been widely used as the filtration and separation industry. Herein, novel microfiltration membranes based on 1-vinyl-3-butylimidazolium chloride ([VBIm][Cl]) grafted PVDF (PVDF-g-[VBIm][Cl]) were prepared via the non-solvent induced phase separation method. The chemical composition and microstructure of PVDF-g-[VBIm][Cl] membranes were characterized by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, Scanning electron microscopy and Water contact angle measurements. The results showed that an increasing in [VBIm][Cl] grafting content leads to the increasing hydrophilicity and wetting capacity of the PVDF-g-[VBIm][Cl] porous membranes. The anti-biofouling properties of membranes were evaluated by measuring the water flux before and after Bovine serum albumin solution treatment. It was found that the modified membranes presented a good anti-biofouling property. The degree of irreversible flux loss caused by protein adsorption dramatically reduced from 42.1% to 2.9% compared with the pristine hydrophobic PVDF membranes. Meanwhile, these PVDF-g-[VBIm][Cl] membranes also exhibited excellent bactericidal properties against both gram-positive bacteria Staphylococcus saureus and gram-negative bacteria Escherichia coli, while PVDF membranes did not show any antibacterial activity. The vitro biocompatibility of the modified membranes was studied by hemolysis analysis, the platelet adhesion observation, thromboelastography assay and cytotoxicity assay. It was found that the incorporation of [VBIm][Cl] into PVDF membranes has less effect on the hemolysis and cytotoxicity of PVDF membranes. Furthermore, both hydrophilicity and charges of the membrane surface played important role in the adhesion and activation of platelet cells, which consequently affected the clotting process of whole blood. The membrane with appropriate [VBIm][Cl] grafting ratio (2.94 wt.%) exhibited good hemocompatibility with less blood coagulation effect. As an ultrafiltration membrane, PVDF-g-[VBIm][Cl] membranes have potential applications in the biomedical field due to the improved antibacterial property and biocompatibility.

New γ-Halo-δ-lactones and δ-Hydroxy-γ-lactones with Strong Cytotoxic Activity.

This paper presents the synthesis of γ -halo- δ -lactones, δ -iodo- γ -lactones and δ -hydroxy- γ -lactones from readily available organic substrates such as trans-crotonaldehyde and aryl bromides. Crystal structure analysis was carried out for lactones that were obtained in crystalline form. All halo- δ -lactones and δ -hydroxy- γ -lactones were highly cytotoxic against gastric cancer AGS cells with I C 50 values in the range of 0.0006-0.0044 mM. Some lactones showed high bactericidal activity against E. coli ATCC 8739 and S. aureus ATCC 65389, which reduced the number of CFU/mL by 70-83% and 87% respectively.

Influence of the surface properties on bactericidal and fungicidal activity of magnetron sputtered Ti-Ag and Nb-Ag thin films.

In this study the comparative investigations of structural, surface and bactericidal properties of Ti-Ag and Nb-Ag thin films have been carried out. Ti-Ag and Nb-Ag coatings were deposited on silicon and fused silica substrates by magnetron co-sputtering method using innovative multi-target apparatus. The physicochemical properties of prepared thin films were examined with the aid of X-ray diffraction, grazing incidence X-ray diffraction, scanning electron microscopy, atomic force microscopy and X-ray photoelectron spectroscopy methods. Moreover, the wettability of the surface was determined. It was found that both, Ti-Ag and Nb-Ag thin films were nanocrystalline. In the case of Ag-Ti film presence of AgTi3 and Ag phases was identified, while in the structure of Nb-Ag only silver occurred in a crystal form. In both cases the average size of crystallites was ca. 11 nm. Moreover, according to scanning electron microscopy and atomic force microscopy investigations the surface of Nb-Ag thin films was covered with Ag-agglomerates, while Ti-Ag surface was smooth and devoid of silver particles. Studies of biological activity of deposited coatings in contact with Bacillus subtilis, Pseudomonas aeruginosa, Enterococcus hirae, Klebisiella pneumoniae, Escherichia coli, Staphylococcus aureus and Candida albicans were performed. It was found that prepared coatings were bactericidal and fungicidal even in a short term-contact, i.e. after 2 h.

Bactericidal properties of the antimicrobial peptide Ib-AMP4 from Impatiens balsamina produced as a recombinant fusion-protein in Escherichia coli.

Antimicrobial peptides (AMPs) represent a novel class of powerful natural antimicrobial agents. As AMPs are bactericidal, production of AMPs in recombinant bacteria is far from trivial. We report the production of Impatiens balsamina antimicrobial peptide 4 (Ib-AMP4, originally isolated from Impatiens balsamina) in Escherichia coli as a fusion protein and investigate Ib-AMP4's antimicrobial effects on human pathogens. A plasmid vector pET32a-Trx-Ib-AMP4 was constructed and transferred into E. coli. After induction, a soluble fusion protein was expressed successfully. The Ib-AMP4 peptide was obtained with a purity of over 90% after nickel affinity chromatography, ultrafiltration, enterokinase cleavage and sephadex size exclusion chromatography. For maximum activity, Ib-AMP4, which possesses two disulfide bonds, required activation with 5 µg/mL H2 O2 . Antimicrobial assays showed that Ib-AMP4 could efficiently target clinical multiresistant isolates including methicillin-resistant Staphylococcus aureus and extended-spectrum ß-lactamase-producing E. coli. Time kill experiments revealed that Ib-AMP4 is bactericidal within 10 min after application. Haemolysis and cytotoxicity assays implied selectivity towards bacteria, an important prerequisite for clinical applications. Ib-AMP4 might be an interesting candidate for clinical studies involving patients with septicemia or for coating clinical devices, such as catheters. The method described here may be applicable for expression and purification of other AMPs with multiple disulfide bridges.