Modern implants are often based on silicon-doped hydroxyapatite for enhanced biological activity. Such materials still have drawbacks, such as high probability of bacterial infections on their ...surface during surgery. In this work, we obtained germanium-substituted calcium phosphates, which are isostructural to silicon-substituted hydroxyapatite and whitlockite. Additionally, they potentially possess antibacterial properties. We obtained Ge-substituted phosphate composition Ca5GeP2O12 by solid-state, sol-gel, and combustion synthesis. The samples were analyzed using powder X-ray diffraction. Solid-phase synthesis leads to the formation of whitlockite, whereas synthesis in solution leads to the formation of hydroxyapatite. The calculation of the grain size distribution shows that the smallest particles are formed when combustion synthesis is used, and the largest particles are obtained during solid-phase synthesis. This is correlated with the expected influence of stirring and temperature factors on the reaction path.
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•Low-temperature syntheses in solutions are an effective way to obtain metastable Ge-substituted hydroxyapatite.•The combustion method produces the smallest particles.•Ge-substituted hydroxyapatite has potential antibacterial properties.
The influence of capping agents on silver nanoparticles (AgNPs) was investigated through a rapid and single-pot chemical reduction method. Four capping agents were tested: polyethylene glycol (PEG), ...ethylenediaminetetraacetic acid (EDTA), polyvinyl pyrrolidone (PVP) and polyvinyl alcohol (PVA). FTIR studies demonstrated that the formed AgNPs were properly encapsulated by their respective capping agents. Structural and morphological studies confirmed the following relative average particle sizes: PEG-AgNPs > EDTA-AgNPs > PVP-AgNPs > PVA-AgNPs. Optical absorption and photoluminescence studies showed, respectively, a greater absorption blue shift and greater emission intensity for the smaller capped particles. Zeta potential analysis of the PVA-AgNPs showed a value of -46.6 mV, indicating their high stability. The PVA-AgNPs were thus not only observed to be the smallest, most blue-shifted and most stable of the tested AgNPs, but also they displayed the highest antibacterial activity. The PVA-AgNPs were therefore applied as a localized surface plasmon resonance (LSPR)-based H sub(2)O sub(2) sensor, which is important because the detection of reactive oxygen species such as H sub(2)O sub(2) is of significance in the medical and environmental fields. The sensor based on the PVA-AgNPs successfully detected H sub(2)O sub(2) at concentrations as low as 10 super(-7) M. New biosensors using these NPs should thus find promising opportunities in a variety of fields.
Inorganic–organic systems based on ZnO or ZnO–SiO2 and lignin were used for the first time to counteract the biodeterioration of cement composites. The stability of the oxide–lignin and ...interoxide–lignin combinations was confirmed by Fourier transform infrared spectroscopy, while electrokinetic studies confirmed the stability of the systems in the alkaline environment of the cement matrix. Moreover, lignin-enriched admixtures showed very good water wettability, which enabled their uniform dispersion in the cement matrix. Physical and mechanical tests confirmed the retarding effect of zinc oxide on the hydration of the cement binder in the initial setting period, which was manifested by lower mechanical parameters up to the 7th day of setting. The use of interoxide systems with silica balanced this adverse effect. The designed systems based on ZnO and lignin caused the inactivation of both bacterial and fungal pathogens, the effect being weaker in the case of the systems with silica.
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•Design, preparation and characterization of ZnO/lignin and ZnO–SiO2/lignin hybrids•Production of novel cement composites using inorganic–organic hybrid admixtures•Species-specific antimicrobial effect of the hybrid materials and cement composites•Positive effect of ZnO and ZnO/lignin on the inhibition of the growth of microorganisms in cement composites
The present work describes the successful synthesize of spinel magnetic ferrite Mn1-xNixFe2O4 (x=0.0, 0.1, 0.2, 0.3, 0.4 & 0.5) nanoparticles via a simple microwave combustion method which was then ...evaluated for its photocatalytic activity in the degradation of indigo carmine (IC) synthetic dye, a major water pollutant. Our results reveal that the synthesized of Ni2+ doped MnFe2O4 nanoparticles possess well-crystalline pure cubic spinel phase, exhibit excellent optical and magnetic properties. Further, the photocatalytic performance of the synthesized nanoparticles at different concentration ratios of Ni2+ ions was monitored by photocatalytic degradation of indigo carmine synthetic dye under UV (λ=365nm) light irradiation. In order to get maximum photocatalytic degradation (PCD) efficiency, we have optimized various parameters, which include catalyst dosage, initial dye concentration, pH and Ni2+ dopant content. It was found that the reaction was facilitated with optimum catalyst dose of 50mg/100mL, high dye concentrations of 150mg/L and acidic pH and among all the synthesized samples, Mn0·5Ni0.5Fe2O4 exhibit superior performance of photocatalytic activity on the degradation of indigo carmine synthetic dye. These results highlighted the potential use of effective, low-cost and easily available photocatalysts for the promotion of wastewater treatment and environmental remediation. In addition, the antibacterial activity of spinel magnetic Mn1–xNixFe2O4 nanoparticles against two Gram positive bacteria (Staphylococcus aureus and Bacillus subtilis) and two Gram negative bacteria (Pseudomonas aeruginosa and Escherichia coli) was also examined. Our antibacterial activity results are comparable with the results obtained using the antibiotic, streptomycin.
•Mn1–xNixFe2O4 nanoparticles are synthesized via simple microwave combustion method.•The photocatalytic degradation of indigo carmine synthetic dye was examined.•Mn0.5Ni0.5Fe2O4 shows superior photocatalytic activity and antibacterial activity.•Mn1–xNixFe2O4 nanoparticles show dual performance.
An improved Knoevenagel condensation yielded three α,β-unsaturated ketones whose photostability and antibacterial properties were evaluated.
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•Three dibenzylideneacetones were ...synthesized by an improved Knoevenagel reaction.•Compound 2 with -N(CH3)2 groups exhibits potential as a broad-spectrum UV filter.•Compounds 2 &3 show good antibacterial activity and are leads for new antibiotics.
A series of three symmetrical α,β-unsaturated ketones, namely, (1E,4E)-1,5-bis4-(methylthio)phenylpenta-1,4-dien-3-one, 1, (1E,4E)-1,5-bis4-(dimethylamino)phenylpenta-1,4-dien-3-one, 2, and (1E,4E)-1,5-bis4-(ethyl)phenyl penta-1,4-dien-3-one, 3, were synthesized in excellent yields (above 70%) and within a short reaction time (1 h), via an improved Knoevenagel condensation with acetyl acetone and substituted benzaldehydes. All the compounds were fully characterized by UV/Vis, IR, NMR and mass spectrometry. In addition, compound 1 was characterized by single crystal X-ray diffraction. The photostability of the prepared compounds was investigated in solvents of different polarity and proticity by exposure to simulated solar radiation. Three solvents were used, namely, ethyl acetate, dimethylsulfoxide and methanol. The change in UV absorption was monitored by a standard spectrophotometric method and photodegradation products were identified by 1H NMR. According to the results, 1 and 3 were not photostable, and suffered significant changes in their UV absorption spectra. Compound 2, on the other hand, was observed to be considerably photostable in the polar protic solvent methanol but less photostable in the polar aprotic solvent dimethylsulfoxide. All three compounds (1–3) photodegraded appreciably in the less polar aprotic solvent ethyl acetate. Therefore, their photostability is solvent dependent. The antibacterial activity of 1–3 was evaluated by means of the modified broth microdilution method against both gram-negative and gram-positive bacterial strains. Compounds 2 (methylated amine) and 3 (ethyl) have electron-releasing substituents and they were found to have excellent activity against all the tested bacteria. Thus, compounds 2 and 3 can be further explored as potential leads for the development of cheaper, safer, more effective and potent antibiotics against both gram-positive and gram-negative bacterial strains, and compound 2 is a good candidate for use in sunscreen formulations if dissolved in a polar solvent.
Curcumin–chitosan (Cur–CH) blend films were prepared by solution casting. The Cur–CH and pure chitosan (PCH) films were characterized by molecular simulation, physicochemical properties and ...antibacterial properties. The molecular model showed that probable interaction between curcumin and chitosan was hydrogen bonding, which was further determined by FTIR. The SEM revealed a good compatibility between curcumin and chitosan. Thermal behavior and X-ray diffraction showed that the structure of Cur–CH film was changed and the crystallinity was decreased compared with PCH film. The blend films showed a larger tensile strength and a higher hydrophilic property than PCH film. Antibacterial activity of Cur–CH film against Staphylococcus aureus and Rhizoctonia solani was studied by the zone inhibition method. Results suggest that it is promising to study natural curcumin chitosan blend films with excellent tensile strength and antibacterial activity for food packaging and agricultural products storage.
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•Chitosan/curcumin films with an excellent antibacterial activity were prepared.•Molecular simulation was used to explain the probable interactions.•The blend films have a good compatibility and a large tensile strength.•The wettability of the blend films were discussed upon hydrogen bonding.
The novel bacteriocin JS17 was obtained from Bacillus subtilis JSX-5, isolated from blueberry (Vaccinium uliginosum) ferments. JS17 was purified by ÄKTA Purifier, semi-preparative reversed-phase high ...performance liquid chromatography, and nano liquid chromatography coupled with tandem mass spectrometry, in succession. Its molecular mass was 652.37 Da and its amino acid sequence was identified as L-F-R-A-F. A homology BLAST search confirmed JS17 as a novel bacteriocin. JS17 was found to have an extensive antibacterial activity spectrum against both Gram-positive and Gram-negative bacteria. JS17 showed heat tolerance, and it was highly stable over pH 2–10 and was sensitive to proteinase K and pepsin. This indicates that JS17 exhibits protein properties and has application potential under high temperature and acid-base conditions. The minimum inhibitory concentration and minimum bactericide concentration of JS17 against Escherichia coli were 10.56 μg/mL and 22.03 μg/mL, respectively, which is lower than that of most previously described bacteriocins. Furthermore, scanning electron microscopy showed that JS17 bactericidally destroyed the cell membrane integrity of E. coli, resulting in cell dissolution and impaired membrane permeability. This study first purified B. subtilis bacteriocin from fruit ferments, suggesting the potential for using JS17 as a food bio-preservative.
•Bacteriocin-producing Bacillus subtilis was isolated from blueberry ferments.•Bacteriocin JS17, purified by SEC columns of AKTA and RP-HPLC.•Molecular weight and amino acid composition were determined.•JS17 was effective against gram positive and negative bacteria.•JS17 was effective at range of temperature (37–121 °C) and pH (2–10).
Enhancing the fire-retardant and antibacterial properties of viscose fabric through a simple strategy is crucial and urgent. In this study, an aminoazole-based cyclotriphosphazene (HATA) was designed ...and synthesized through nucleophilic substitution between hexachlorocyclotriphosphazene and 3-amino-1,2,4-triazole. The application of a rapid dipping strategy and the use of 10 wt% HATA aqueous solution significantly increased the limiting oxygen index of the viscose fabric from 19.3 % to 28.4 %. In addition, the HATA-treated fabric exhibited self-extinguishing properties in vertical flame testing. The peak heat release rate of HATA-treated fabric, according to pyrolysis combustion flow calorimetry, significantly decreased by over 83 %. The scanning electron microscope images revealed the original woven fabric structure after burning. The thermogravimetric infrared spectroscopy and X-ray photoelectron spectroscopy results confirmed that the introduction HATA in viscose hindered the release of combustible gas and facilitated the formation of a protective char layer. In addition, 10 % HATA-viscose exhibited remarkable antimicrobial properties, achieving 99.96 % and 99.84 % antibacterial rates against Staphylococcus aureus and Escherichia coli, respectively. Furthermore, HATA-treated viscose fabric exhibited favorable mechanical performance, whiteness, and air permeability. This research provides a simple and effective flame-retardant and antibacterial treatment strategy for viscose fabric.
Starch-based films are degradable, renewable, cost effective, and can be used as a foodstuff packaging material. Functional starch-based films have attracted extensive attention from researchers in ...recent years. Bioactive starch-based films with antibacterial, anti-oxidation, UV, oxygen, and water vapor barriers can reduce the reproduction of microorganisms and prolong the shelf life of packaged foods. Intelligent starch-based films with pH-, temperature-, magnetic field-, glucose-, and enzyme-responsive characteristics can be used to monitor the freshness of foods and control the delivery of functional ingredients and drugs. Therefore, the development of biodegradable bioactive and intelligent starch-based films is particularly important.
In this review, we first introduce three common methods for preparing starch-based films and their advantages and disadvantages. Then, the bioactive and intelligent properties of starch-based films are discussed. Finally, examples are used to illustrate the application of active and intelligent starch-based films in food packaging and other areas.
The addition of plant extracts, plant essential oils, and nanoparticles to starch films can improve their antibacterial, antioxidant, and barrier properties. The addition of anthocyanins to starch films can make the films pH-responsive, indicating the degree of spoilage in fish products and achieving the purpose of warning consumers. In the future, it is necessary to study other biologically active starch-based films, such as anti-fatigue, enzyme-responsive, and salt-responsive starch-based films.
•Three preparation methods of starch-based films are introduced.•The bioactive films have antibacterial, anti-oxidation, and barrier properties.•The smart films have pH-, magnetic field-, and enzyme-responsive characteristics.•The films are widely used in food packaging, drug delivery and other aspects.
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Bacterial infection of biomedical implants is an important clinical challenge, driving the development of novel antimicrobial materials. The antibacterial effect of vertically aligned ...graphene as a nanoarray coating has been reported. In this study, vertically aligned graphene nanosheets decorated with silver nanoparticles were fabricated to enhance antibacterial effectiveness. Vertical graphene (VG) nanoflakes were synthesized by plasma-enhanced chemical vapor deposition (PECVD). Ag nanoparticles were attached to the surface of VG through using polydopamine and achieving a sustained release of Ag+. VG loaded with Ag nanoparticles (VGP/Ag) not only prevented bacterial adhesion for a long time, but also exhibited good biocompatibility. This work provides a new venue for designing antibacterial surfaces based on combination of graphene nanoarrays with other nanomaterials, and the results indicate that this approach could be very successful in preventing implant associated infections.
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