Electrospun PCL Filtration Membranes Enhanced with an Electrosprayed Lignin Coating to Control Wettability and Anti-Bacterial Properties

This study reports on the two-step manufacturing process of a filtration media obtained by first electrospinning a layer of polycaprolactone (PCL) non-woven fibers onto a paper filter backing and subsequently coating it by electrospraying with a second layer made of pure acidolysis lignin. The manufacturing of pure lignin coatings by solution electrospraying represents a novel development that requires fine control of the underlying electrodynamic processing. The effect of increasing deposition time on the lignin coating was investigated for electrospray time from 2.5 min to 120 min. Microstructural and physical characterization included SEM, surface roughness analysis, porosity tests, permeability tests by a Gurley densometer, ATR-FTIR analysis, and contact angle measurements vs. both water and oil. The results indicate that, from a functional viewpoint, such a natural coating endowed the membrane with an amphiphilic behavior that enabled modulating the nature of the bare PCL non-woven substrate. Accordingly, the intrinsic hydrophobic behavior of bare PCL electrospun fibers could be reduced, with a marked decrease already for a thin coating of less than 50 nm. Instead, the wettability of PCL vs. apolar liquids was altered in a less predictable manner, i.e., producing an initial increase of the oil contact angles (OCA) for thin lignin coating, followed by a steady decrease in OCA for higher densities of deposited lignin. To highlight the effect of the lignin type on the results, two grades of oak (AL-OA) of the Quercus cerris L. species and eucalyptus (AL-EU) of the Eucalyptus camaldulensis Dehnh species were compared throughout the investigation. All grades of lignin yielded coatings with measurable antibacterial properties, which were investigated against Staphylococcus aureus and Escherichia coli, yielding superior results for AL-EU. Remarkably, the lignin coatings did not change overall porosity but smoothed the surface roughness and allowed modulating air permeability, which is relevant for filtration applications. The findings are relevant for applications of this abundant biopolymer not only for filtration but also in biotechnology, health, packaging, and circular economy applications in general, where the reuse of such natural byproducts also brings a fundamental demanufacturing advantage.

Chemical and Structural Assessment of New Dental Composites with Graphene Exposed to Staining Agents

Among the newest trends in dental composites is the use of graphene oxide (GO) nanoparticles to assure better cohesion of the composite and superior properties. Our research used GO to enhance several hydroxyapatite (HA) nanofiller distribution and cohesion in three experimental composites CC, GS, GZ exposed to coffee and red wine staining environments. The presence of silane A-174 on the filler surface was evidenced by FT-IR spectroscopy. Experimental composites were characterized through color stability after 30 days of staining in red wine and coffee, sorption and solubility in distilled water and artificial saliva. Surface properties were measured by optical profilometry and scanning electron microscopy, respectively, and antibacterial properties wer e assessed against Staphylococcus aureus and Escherichia coli. A colour stability test revealed the best results for GS, followed by GZ, with less stability for CC. Topographical and morphological aspects revealed a synergism between GZ sample nanofiller components that conducted to the lower surface roughness, with less in the GS sample. However, surface roughness variation due to the stain was affected less than colour stability at the macroscopic level. Antibacterial testing revealed good effect against Staphylococcus aureus and a moderate effect against Escherichia coli.

Development of Antifouling Thin-Film Composite/Nanocomposite Membranes for Removal of Phosphate and Malachite Green Dye

Nowadays polymer-based thin film nanocomposite (TFN) membrane technologies are showing key interest to improve the separation properties. TFN membranes are well known in diverse fields but developing highly improved TFN membranes for the removal of low concentration solutions is the main challenge for the researchers. Application of functional nanomaterials, incorporated in TFN membranes provides better performance as permeance and selectivity. The polymer membrane-based separation process plays an important role in the chemical industry for the isolation of products and recovery of different important types of reactants. Due to the reduction in investment, less operating costs and safety issues membrane methods are mainly used for the separation process. Membranes do good separation of dyes and ions, yet their separation efficiency is challenged when the impurity is in low concentration. Herewith, we have developed, UiO-66-NH₂ incorporated TFN membranes through interfacial polymerization between piperazine (PIP) and trimesoyl chloride (TMC) for separating malachite green dye and phosphate from water in their low concentration. A comparative study between thin-film composite (TFC) and TFN has been carried out to comprehend the benefit of loading nanoparticles. To provide mechanical strength to the polyamide layer ultra-porous polysulfone support was made through phase inversion. As a result, outstanding separation values of malachite green (MG) 91.90 ± 3% rejection with 13.32 ± 0.6 Lm^-2h^-1 flux and phosphate 78.36 ± 3% rejection with 22.22 ± 1.1 Lm^-2h^-1 flux by TFN membrane were obtained. The antifouling tendency of the membranes was examined by using bovine serum albumin (BSA)-mixed feed and deionized water, the study showed a good ~84% antifouling tendency of TFN membrane with a small ~14% irreversible fouling. Membrane's antibacterial test against E. coli. and S. aureus. also revealed that the TFN membrane possesses antibacterial activity as well. We believe that the present work is an approach to obtaining good results from the membranes under tricky conditions.

Zeolite-Supported Aggregate as Potential Antimicrobial Agents in Gypsum Composites

Relatively easy treatment of glass aggregates can lead to the formation of a highly porous zeolite aggregate. This study focuses on the possibility of using such an aggregate as an active additive to a gypsum binder. The physical properties of hardened gypsum composites with zeolite fillers doped with various metal ions (Ni²⁺, Cu²⁺, and Zn²⁺) have been compared. In addition to studies of the basic physical properties of the composites, structural and microstructural studies as well as antimicrobial tests were performed. It was found that the parameters of the composites with the addition of various ions do not differ significantly from the reference but modifies the microstructure. Among other things, the ions analyzed reduce the microporosity of gypsum composites. Using all aggregates, a product with adequate strength (above 2 MPa) and thermal conductivity (about 0.35 W/m·K) appropriate for typical lightweight gypsum composites can be obtained. The bacteriostatic effect of formulations with copper and zinc against Escherichia coli and with copper against Staphylococcus aureus was found.

The In Situ Hydrothermal and Microwave Syntheses of Zinc Oxides for Functional Cement Composites

This study presents the results of research on cement mortars amended with two zinc oxides obtained by two different methods: hydrothermal ZnO-H and microwave ZnO-M. Our work indicates that, in contrast to spherical ZnO-H, ZnO-M was characterized by a columnar particle habit with a BET surface area of 8 m²/g, which was four times higher than that obtained for hydrothermally obtained zinc oxide. In addition, ZnO-M induced much better antimicrobial resistance, which was also reported in cement mortar with this oxide. Both zinc oxides showed very good photocatalytic properties, as demonstrated by the 4-chlorophenol degradation test. The reaction efficiency was high, reaching the level of 90%. However, zinc oxides significantly delayed the cement binder setting: ZnO-H by 430 min and ZnO-M by 380 min. This in turn affected the increments in compressive strength of the produced mortars. No significant change in compressive strength was observed on the first day of setting, while significant changes in the strengths of mortars with both zinc oxides were observed later after 7 and 28 days of hardening. As of these times, the compressive strengths were about 13-15.5% and 12-13% higher than the corresponding values for the reference mortar, respectively, for ZnO-H and ZnO-M. There were no significant changes in plasticity and flexural strength of mortars amended with both zinc oxides.

Quantitative Evaluation of Nucleic Acid Degradability of Copper Alloy Surfaces and Its Correlation to Antibacterial Activity

Copper (Cu) and its alloys have bactericidal activity known as “contact killing” with degradation of nucleic acids inside the bacteria, which is beneficial to inhibit horizontal gene transfer (HGF). In order to understand the nucleic acid degradability of Cu and its alloy surfaces, we developed a new in vitro method to quantitatively evaluate it by a swab method under a “dry” condition and compared it with that of commercially available antibacterial materials such as antibacterial stainless steel, pure silver, and antibacterial resins. As a result, only Cu and its alloys showed continuous degradation of nucleic acids for up to 6 h of contact time. The nucleic acid degradability levels of the Cu alloys and other antibacterial materials correlate to their antibacterial activities evaluated by a film method referring to JIS Z 2801:2012 for Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aureus) bacteria. Nucleic acid degradation by copper (I) and (II) chlorides was confirmed at the ranges over 10 mM and 1–20 mM, respectively, suggesting that the copper ion release may be responsible for the degradation of the nucleic acids on Cu and its alloy surfaces. In conclusion, the higher Cu content in the alloys gave higher nucleic acid degradability and higher antibacterial activities.

Initiated Chemical Vapor Deposition of Crosslinked Organic Coatings for Controlling Gentamicin Delivery

A coating consisting of a copolymer of methacrylic acid and ethylene glycol dimethacrylate was deposited over a gentamicin film by initiated chemical vapor deposition with the aim of controlling the drug release. Gentamicin release in water was monitored by means of conductance measurements and of UV-vis Fluorescence Spectroscopy. The influence of the polymer chemical composition, specifically of its crosslinking density, has been investigated as a tool to control the swelling behavior of the initiated chemical vapor deposition (iCVD) coating in water, and therefore its ability to release the drug. Agar diffusion test and microbroth dilution assays against Staphylococcus aureus and Pseudomonas aeruginosa on cellulose coated substrates confirmed that the antibacterial activity of the drug released by the coating was retained, though the release of gentamicin was not complete.

Influence of Dopant Nature on Biological Properties of ZnO Thin-Film Coatings on Ti Alloy Substrate

In this paper, ZnO and Co2+/Mg2+-doped ZnO thin films on TiAlV alloy substrates were obtained. The films were deposited by spin coating of sol-gel precursor solutions and thermally treated at 600 °C for 2 h, in air and slow cooled. The doping ions concentration was 1.0 mol%. The study's aim was to obtain implantable metallic materials with improved biocompatibility and antibacterial qualities. The characteristics of the thin films were assessed from the point of view of microstructure, morphology, wetting properties, antibacterial activity and biological response in the presence of amniotic fluid stem cells (AFSC). The results proved that all deposited samples were nanostructured, suggesting a very good antibacterial effect and proving to be suitable supports for cellular adhesion and proliferation. All properties also depended on the doping ion nature.

[Preliminary study on antibacterial activity of artemisinin and its derivatives]

In this study,in order to detect the antimicrobial activity of artemisinin and its derivatives artesunate and dihydroartemisinin,two methods including broth dilution and plate punching method were used to detect the antibacterial activity against gram-negative bacteria(Escherichia coli)and gram-positive bacteria(Staphylococcus aureus)of artemisinin,dihydroartemisinin and artesunate at various concentrations within 5 mmol·L~(-1)and at four time points(8,16,24,32 h).Two antibacterial positive drugs,streptomycin against E.coli and penicillin against S.aureus,were used as positive controls.Plate punching method showed that,unlike the results of 5 mmol·L~(-1)dihydroartemisinin or artesunate,no inhibition zone was detected at the same concentration of artemisinin after 24 h-treatment against E.coli.Broth dilution method showed that,the antibacterial activity of dihydroartemisinin against E.coli.was stronger than those of both artesunate and artemisinin;IC_(50)at24 h-treatment was 155.9μmol·L~(-1)for dihydroartemisinin,370.0μmol·L~(-1)for artesunate and none for artemisinin.Interestingly,dihydroartemisinin and artesunate showed the strongest antibacterial activity between 16-24 h,while artemisinin showed relatively stronger antibacterial activity between 8-16 h.Dihydroartermisinin showed no antibacterial activity against S.aureus.Above all,the antibacterial activity of artemisinins against E.coli is dihydroartemisinin>artesunate>artemisinin.Artemisinin and its derivatives have showed different antibacterial kinetics,and no antibacterial activity against S.aureus.has been detected with dihydroartemisinin.

Characterization and biological properties of a novel synthesized silicon-substituted hydroxyapatite derived from eggshell

In the present study, the effect of adding different concentrations of silicon on physical, mechanical and biological properties of a synthesized aqueous precipitated eggshell-derived hydroxyapatite (e-HA) was evaluated. No secondary phases were detected by X-ray diffraction for the specimens e-HA and e-HA containing silicon (Si-e-HAs) before and after heating at 1200°C. A reduction in the crystallite size and a-axis as well as an increase in c-axis was occurred when silicon replacement was happened in the structure of e-HA. The presence of Si-O vibrations and carbonate modes for Si-e-HAs was confirmed by Fourier transform infrared spectroscopy analysis. The range of porosity and density was varied from 25% and 2.4 g cm^-3 to 7% and 2.8 g cm^-3 for e-HA and Si-e-HAs. The values of Young's modulus ( E) and compressive strength were varied for e-HA and Si-e-HAs. The porous structure of the samples was reduced when they were heated as e-HA kept the porous microstructure containing some dense areas and Si-e-HAs possessed a rough surface including slight levels of microporosity. The acellular in vitro bioactivity represented different apatite morphologies for e-HA and Si-e-HAs. The G-292 osteoblastic cells were stretched well on the surface with polygon-shaped morphology for 0.8Si-e-HA after 7 days of culture. According to MTT assay and alkaline phosphatase test, the maximum cell activity was related to 0.8Si-e-HA. The minimum inhibitory concentration for 0.8Si-e-HA and e-HA was estimated to be about 3.2 and 4.4 mg/mL, respectively. In overall, the sample 0.8Si-e-HA exhibited a higher bacteriostatic effect than e-HA against gram-negative bacterial strain Escherichia coli.

Development of HA/Ag-NPs Composite Coating from Green Process for Hip Applications

In the present study, biological hydroxyapatite (HA) was obtained from bovine bones through a thermal process. A total of 0% and 1% of silver nanoparticles (Ag-NPs) synthesized from Opuntia ficus (nopal) were added to the biological hydroxyapatite coatings using an atmospheric plasma spray (APS) on a Ti6Al4V substrate. Following this, its antimicrobial efficiency was evaluated against the following bacterial strains: Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa. This was conducted according to the Japanese Industrial Standard (JIS) Z2801:2000 “Antimicrobial Product-Test for Antimicrobial Activity and Efficacy”. Scanning electron microscopy (SEM) showed that the silver nanoparticles (Ag-NPs) were evenly distributed on the coating surface. Energy dispersive X-ray spectroscopy (EDX) shows that apatite deposition occurs on a daily basis, maintaining a Ca/P rate between 2.12 and 1.45. Biocompatibility properties were evaluated with osteoblast-like cells (MC3T3-E1) by single-cell gel electrophoresis assay and Tali image cytometry.