► Complete removal of levofloxacin and antibiotic activity was observed for both treatments. ► Ozonation products were shown to be resistant to further ozonation. ► Higher mineralization efficiency ...was observed for photocatalysis. ► Treating ozonated samples with photocatalysis lead to further removal of ozonation products.
Removal of the fluoroquinolone antibiotic levofloxacin (LEVO) was studied in two oxidation processes: photocatalysis (UVC lamp (254nm), TiO2) and ozonation. LEVO (Co=20mg/L) was no longer detected after an ozone dose of 20.5mg/L and after 180min of photocatalytic oxidation. COD removals of 59% and 70% were measured for 270mg/L of transferred ozone dose and 300min of photocatalytic oxidation, respectively. Extensive treatment with ozone did not result in further reduction in COD levels reaching a plateau at the above mentioned value, however increased irradiation time led to increased COD removal during photocatalytic treatment. Both treatment methods proved to be effective ways of removing antibacterial activity. From agar diffusion test with Escherichia coli, it was observed that a transferred ozone dose of at least 20.5mg/L and 180min of irradiation were enough to completely remove antibacterial activity. Both treatments methods were shown to efficiently remove LEVO and its antibacterial activity and show promising results as possible applications for removal of antibiotics in wastewater.
Some petroleum-based packaging materials have a series of safety issues, and as a result, people are more inclined to use biodegradable and nontoxic packaging materials for foods. However, ...biodegradable alternatives often need to be modified to overcome their own shortcomings. In this paper, carboxymethyl chitosan (CMCS)/carboxymethyl cellulose sodium (CMC) + polylactic acid (PLA) nano zinc oxide (ZnO) nanoparticles (CMCS/CMC + PLA/ZnO NPs) multilayer coated paperboard was prepared to explore its potential use in food package applications. The multilayer CMCS/CMC + PLA coating reduced the oxygen transmission rate by 99% and doubled the barrier properties for soybean oil penetration and water vapor compared with a single PLA coating layer in a 23 °C/50 RH environment. The oil resistance time of the multilayer CMCS/CMC + PLA coating also increased 28 times, and the water vapor barrier properties increased twofold compared to a single CMCS/CMC coating layer. The water vapor barrier properties increased by a factor of 3 even at 38 °C/90 RH. Compared with the CMCS/CMC + PLA coating without nanoparticles, the barrier performance of the CMCS/CMC + PLA/ZnO NPs coating was further improved. The oxygen, water vapor, and heptane vapor barrier properties all doubled, and the oil resistance time reached 235 h. While a corona treatment reduced the polar component content in the CMCS/CMC coating and led to a slight decrease in the barrier properties of the coating to heptane, it was still a good oil-repellent coating overall. The antibacterial activity (A) toward Escherichia coli and Staphylococcus aureus exceeded 2, which meant that the multilayer coating with 1.5% added ZnO NPs reduced the growth of bacteria by more than 99%. The multilayer coated paperboard created here with the blended and modified materials significantly improved the barrier and antibacterial properties, suggesting that multilayer coatings prepared from degradable materials have good commercial prospects as fast food packaging.
Ag NP/GO nanocomposites have been synthesized by the in situ reduction with hydroquinone and can be used as a bacteria killer or to prepare paper like materials. Display omitted
► Nanocomposites were ...prepared via in situ reduction of silver on graphene oxide nanosheets. ► The presence of silver nanoparticles is evidenced by a change in the physicochemical property of graphene oxide. ► Graphene oxide’s antibacterial ability is greatly enhanced. ► Bacterial inactivation of the composites is retained in aquatic media.
Graphene oxide (GO) nanosheets impregnated with silver nanoparticles (Ag NPs) were fabricated by the in situ reduction of adsorbed Ag+ by hydroquinone (HQ) in a citrate buffer solution. Paper-like Ag NP/GO composite materials were fabricated owing to convenient structure characterization and antibacterial tests. The Ag NP/GO composites were characterized by UV–vis spectra, transmission electron microscope, electron diffraction, Raman spectroscopy, and field emission scanning electron microscope coupled with Energy Dispersive Spectrometer. Antibacterial activity was tested using Escherichia coli and Staphylococcus aureus as model strains of Gram negative and Gram positive bacteria, respectively. The as-prepared composites exhibit stronger antibacterial activity against both. The Ag NP/GO composites performed efficiently in bringing down the count of E. coli from 106cfu/mL to zero with 45mg/L GO in water. The micron-scale GO nanosheets (lateral size) enable them to be easily deposited on porous ceramic membranes during water filtration; making them a promising biocidal material for water disinfection.
Antibacterial materials are preferable for water treatment a medical applications. In the present study, to improve the antimicrobial performance of flexible polyurethane (PU) foams, copper ...nanoparticles were in situ generated. The Cu nanoparticles were formed on the surface of polyurethane cell walls with sizes of 100–130 nm, and exhibited high affinity with the PU matrix. Although the cell structure of the nanocomposite PU foams was not greatly influenced, the open cell content decreased slightly from 97.42 to 96.64%. The bound metal nanoparticles on the cell walls could strengthen the cell skeleton improved the mechanical strength of the resulting foams. The mechanical parameters were dramatically improved, such as tensile and compressive strength of the nanocomposite PUs were improved from 78.1 to 94.2 kPa and from 3.80 to 5.63 kPa, respectively. Besides, these nanocomposite foams showed great antibacterial activity that can be considered for antibacterial applications in water treatment and medical fields.
Methicillin-resistant Staphylococcus aureus(MRSA) is a biofilm-forming pathogen that can cause serious health complications in humans, ranging from minor to life-threatening infections. The challenge ...of successfully combating biofilms requires the discovery of compounds with a novel mode of action. We have recently developed sequence-random hydrophobic-cationic peptides that display a broad antibacterial activity. In the current study we show that our novel compounds are capable of controlling and managing MRSA biofilms and might be used as lead biofilm inhibitor candidates for further studies.
Micro/nano scale surface modifications of titanium based orthopedic and cardiovascular implants has shown to augment biocompatibility. However, bacterial infection remains a serious concern for ...implant failure, aggravated by increasing antibiotic resistance and over usage of antibiotics. Bacteria cell adhesion on implant surface leads to colonization and biofilm formation resulting in morbidity and mortality. Hence, there is a need to develop new implant surfaces with high antibacterial properties. Recent developments have shown that superhydrophobic surfaces prevent protein and bacteria cell adhesion. In this study, a thermochemical treatment was used modify the surface properties for high efficacy antibacterial activity on titanium surface. The modification led to a micro‐nano surface topography and upon modification with polyethylene glycol (PEG) and silane the surfaces were superhydrophilic and superhydrophobic, respectively. The modified surfaces were characterized for morphology, wettability, chemistry, corrosion resistance and surface charge. The antibacterial capability was characterized with Staphylococcus aureus and Escherichia coli by evaluating the bacteria cell inhibition, adhesion kinetics, and biofilm formation. The results indicated that the superhydrophobic micro‐nano structured titanium surface reduced bacteria cell adhesion significantly (>90%) and prevented biofilm formation compared to the unmodified titanium surface after 24 h of incubation.
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•Addition of gold nanoparticles at the concentration of 5X increased flexural strength of dentin adhesive by 75%.•Tensile diameter strength of adhesive increased 65% compared to the ...based adhesive by adding nanoparticles.•Multiscale modeling was used to calculate stress and strain distribution around the nanoparticles successfully.•Incorporation of gold nanoparticles has increased the cell viability in the base adhesive.•Adhesive with the 5X concentration of gold NPs had a bacterial growth inhibition zone with a diameter of 2 mm.
In this study, colloidal gold nanoparticles (NPs) with sizes less than 20 nm were added to the dentin adhesive in various concentrations to achieve favorable antibacterial properties. The effect of gold NPs on mechanical, antibacterial, and cytotoxicity features of adhesive was evaluated systematically. It was shown that the addition of gold NPs at the concentration of 5X (i) increased flexural strength of dentin tooth adhesive by 75%, (ii) increased the micro-shear bond strength by 60%, and (iii) increased the tensile diameter strength of adhesive by 65% compared to the based adhesive. Multiscale modeling was used to simulate and calculate stress and strain distribution around the nanoparticles and within the adhesive matrix. Antibacterial properties of adhesives containing gold NPs were examined using disk diffusion and the pour plate methods. The results showed that adhesive with the 5X concentration of gold NPs had a bacterial growth inhibition zone with a diameter of 2 mm is in the disk diffusion method which indicates the antibacterial characteristics of adhesive at this concentration. Also, the antibacterial effect of adhesive-containing NPs was observed in the pour plate method and the reduction of bacterial growth is increased by the addition of nanoparticles. The cytotoxicity of NPs is examined in pure form and combination with dental adhesive using the MTT assay. The results showed that pure gold NPs have shown no toxicity for the growth of cells and the incorporation of gold NPs has increased the cell viability in the base adhesive.
Infected bone defects (IBD) are a challenging problem in orthopedic practice. Biomaterials have attracted attention as a novel approach to overcome this challenge instead of using conventional ...strategies. Graphene, a two-dimensional carbon allotrope, has been shown to possess multiple advantages, such as osteogenesis-promoting activity, a large surface area for drug delivery, and antibacterial activities. However, these attractive merits have not been entirely explored or introduced for the management of IBD. Herein, a novel approach using a vancomycin-laden, self-assembled, graphene-based material against IBD was developed, and the approach uses a single-stage bone graft instead of multiple procedures. Owing to the pi - pi bonding with graphene, vancomycin can be promptly delivered in the initial stage, followed by a sustained release, which ensures the rapid elimination of an infection and provides a durable pathogen revival inhibition via the inherent antibacterial activity of graphene. Moreover, the 3D porous structure incorporated with nano-hydroxyapatite (nHA) provided a biomimetic microenvironment favored by cell adhesion and osteogenic differentiation. Further evaluation of this system in an IBD animal model demonstrated prompt control of infection and promotion of bone regeneration. These results revealed the potential of this approach to be an effectual solution for IBD treatment and a new area of graphene application in the future.
Biofouling is a major problem for the application of membrane technology in water and wastewater treatment. One of the practical strategies to decrease biofouling is the use of advanced ...anti-biofouling membrane material. In this study, different amounts of biogenic silver nanoparticles (bio-Ag0) were embedded in polyethersulfone (PES) membranes, using the phase-inversion method. The effects of the bio-Ag0 content on the structure of the membrane and its filtration performance were systematically investigated. The results demonstrated that silver-containing nanostructures were uniformly distributed on membrane surface. Bio-Ag0 incorporation slightly increased the hydrophilicity of the PES membrane and increased the permeate flux. The anti-bacterial and anti-biofouling properties of the bio-Ag0/PES nanocomposites membrane were tested with pure cultures (Escherichia coli and Pseudomonas aeruginosa) and a mixed culture (an activated sludge bioreactor), respectively. The bio-Ag0/PES composite membranes, even with the lowest content of biogenic silver (140mgbio-Ag0m−2), not only exhibited excellent anti-bacterial activity, but also prevented bacterial attachment to the membrane surface and decreased the biofilm formation during a 9 weeks test.
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► Bio-Ag0 increased the hydrophilicity and permeate flux. ► The bio-Ag0/PES membrane exhibited excellent anti-biofouling property. ► Silver loss was effectively prevented by bio-Ag0. ► Anti-biofouling effect lasted for long term.
The current study was aimed to develop a transparent wound dressing comprised of bacterial cellulose (BC) and poly (2-hydroxyethyl methacrylate) (PHEMA) hydrogel coated with silver (Ag) ...nanoparticles. Briefly, different concentrations of BC whiskers (BCWs) were added into the HEMA solution to form PHEMA/BCWs hydrogel with volume ratio of monomer HEMA and BCWs as 7:3 and 1:1. The addition of BCWs into PHEMA matrix improved its equilibrium water content and light transmittance about 20%-40% and 10%, respectively. The Young's modulus for PHEMA was found to be 0.72MPa, which was improved to 0.57MPa and 0.50MPa for PHEMA/BCWs 7:3 and PHEMA/BCWs 1:1, respectively. Further, immersion of PHEMA/BCWs hydrogel in the AgNO3 and NaBH4 solutions bestowed it with antibacterial property and produced inhibition zones of 0.5±0.15cm and 0.25±0.15cm against Escherichia coli and Staphylococcus aureus, respectively. Similarly, PHEMA/BCWs prepared with 0.001M AgNO3 and 0.001M NaBH4 solutions showed 99% and 90% reduction in colony forming unit (CFU) for E. coli and S. aureus, respectively, after 24h. The PHEMA/BCWs/Ag hydrogel facilitated the growth of NIH3T3 fibroblast, showing their low toxicity. These results demonstrate the suitability of PHEMA/BCWs/Ag hydrogel for its application as potential transparent wound dressing material for skin repair.
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