Sufficient Antibacterial Activity Research Articles

Electrospun collagen/chitosan composite fibrous membranes for accelerating wound healing

The protein-polysaccharide nanofibers have attracted intensive attention in promoting wound healing, due to their components and nanoscale fibrous structure that mimics the native extracellular matrix (ECM). For the full-thickness wounds, in addition to promoting healing, hemostatic property and antibacterial activity are also of critical importance. However, currently, protein-polysaccharide-based nanofiber membranes exhibit poor mechanical properties, lack inherent hemostatic and antibacterial capabilities, as well as the ability to promote tissue repair. In this study, we developed composited membranes, which were composed of collagen (Col) and chitosan (Chs), through solvent alteration and post-processing, the membranes showed enhanced stability under physiological conditions, proper hydrophilic performance and improved mechanical property. Appropriated porosity and water vapor transmission rate, which benefit to wound healing, were detected among all the membranes except for Col membrane. Aimed at wound dressing, hemocompatibility, antibacterial activity and cell proliferation of the electrospun membranes were evaluated. The results indicated that the Col/Chs composited membranes exhibited superior blood clotting capacity, and the membranes with Chs exceeding 60% possessed sufficient antibacterial activity. Moreover, compared with Chs nanofibers, significant increase in cell grow was detected in Col/Chs (1:3) membrane. Taken together, the electrospun membrane with multiple properties favorable to wound healing, superior blood coagulation, sufficient antibacterial performance and promoting cell proliferation property make it favorable candidate for full-thickness skin wound healing.

Fabrication and characterization of an innovative g-C3N4/calcium/aloe vera enriched PVA-bacterial cellulose wound dressing: A novel approach to diabetic wound management

Nanofiber scaffolds are of particular interest due to the conducive conditions they offer for wound healing. The objective and novelty of this study was to fabricate graphitic carbon nitride/calcium/aloe vera nanocomposites and PVA/bacterial cellulose/calcium/aloe vera nanofibers via electrospinning in preparation for their application as wound dressings. Initial evaluations and production of graphitic carbon nitride (g-C3N4), g-C3N4/calcium solution, and g-C3N4/calcium/Aloe Vera solution were conducted using XRD and FTIR, which accordingly, the results confirmed the successful integration of every component within the nanocomposite structure. Moreover, the antibacterial activity of the developed materials was assessed using the bacterial growth inhibitor (MIC). The results indicated that the materials possessed sufficient antibacterial activity against both gram-positive S. aureus and gram-negative E. coli bacteria with a dilution of 1/512. The nanofibers that were generated were subsequently examined using XRD and SEM techniques with a thickness of 250 nm. Also, the evaluation of the mechanical properties was performed by subjecting PVA/BC/g-C3N4/Ca/Aloe vera nanofibers to tensile strength testing and biodegradation, which these revealed 61.0 % of elongation, and 7 % of biodegradability in 96 h. The outcomes demonstrated that the nanocomposite possessed adequate extension capacity and robust strength. Utilizing an animal model, the developed nanofibers were utilized to examine the healing of diabetic lesions. The wound healing process was observed to be accelerated by these nanofibers after a 21-day period. The area of the lesion measured 0.9891 cm2.

Bio‐based pH‐responsive nanofibrous membranes for controlled release of tetracycline hydrochloride

AbstractDesign and fabrication of pH‐responsive nanofibrous membranes by biomaterials is a key step for drug delivery systems. Currently, there is an increasing attention on design of biocompatible nanofibrous drug delivery systems. Here, a bio‐based pH‐responsive nanofibrous membranes loaded with antibiotic were fabricated for the controlled release of tetracycline hydrochloride (TH). The in vitro drug release behavior of varied pH‐responsive nanofibrous with different mass ratios of poly (lactic acid) (PLA) and cellulose acetate phthalate (CAP) was investigated to clarify the release mechanism. TH initial burst release within 20 mins was large than 97.5% for PLA/CAP/TH NFM under alkaline conditions (pH = 8). The antioxidant activity of TH loaded PLA/CAP NFMs are all higher than 55% after 30 mins. The prepared fibrous membranes possess sufficient antibacterial activity against both to Gram‐negative and Gram‐positive bacteria. At the same time, it also has good biocompatibility. Therefore, the fabricated nanofibrous membranes was demonstrated to be a pH‐responsive nanoplatform for drug delivery.

Cefminox sodium carbon nanodots for treatment and bacterial detection of bloodstream infection

Cefminox sodium carbon nanodots were synthesized via a rapid one-step microwave method using cefminox sodium as sole precursor. The prepared cefminox sodium carbon nanodots had good water solubility and the diameter was concentrated at 1.29 ± 0.40 nm with relative uniform. They exhibited fluorescence excitation-dependent property, of which optimal excitation wavelength was ∼ 390 nm, and optimal emission wavelength was ∼ 465 nm. As retained part of the structure and antibacterial properties of cefminox sodium, cefminox sodium carbon nanodots had low biological toxicity and sufficient antibacterial activity against bacteria in vitro. In vivo experiments demonstrated cefminox sodium carbon nanodots could exert a good therapeutic effect on acute bloodstream infection. In the mixed solution (Escherichia coli, blood and cefminox sodium carbon nanodots), the fluorescent intensity exhibited quadratic functional relationship with the concentration of Escherichia coli. The detection concentration range for Escherichia coli was 0.5 × 106 ∼ 1 × 109 CFU/mL, and the detection limit was 3.7 × 105 CFU/mL. It suggested cefminox sodium carbon nanodots can rapidly and quantitatively detect the number of Escherichia coli in blood while effectively treating bloodstream infection. Due to the long period of clinical detection time (about 1–5 days or more) for bacterial counts in the blood of patients, this method provides a new strategy for rapid clinical treatment and effective monitoring of the degree of infection in patients.

Fabrication of titanium incorporation into zeolitic imidazolate framework-L on fabric carrier for visible-light driven photocatalytic antibacterial activity

The development of metal–organic frameworks (MOFs) as a nanoplatform for emerging antibacterial agents has gained great attention. In this work, TiO2 nanoparticles in-situ incorporated in zeolitic imidazolate framework-L (ZIF-L) successfully grow on the non-textile fabric substrate as a novel antibacterial composite ZIF-L@TiO2/fabric with improved visible-light driven antibacterial activity. The morphology and composition of the as-prepared antibacterial composite are characterized via SEM, TEM, XRD, and XPS analysis. The material with high light use efficiency can generate more reactive oxygen species (ROS) under light irradiation than that in dark, which suggests the synergistic effect between TiO2 nanoparticles and ZIF-L in the visible region. Correspondingly, ZIF-L@TiO2/fabric exhibits outstanding antibacterial effect against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), which can also be verified by the Leica SP5 laser scanning confocal microscope (LSCM) results. Furthermore, the possible antibacterial mechanism is proposed. Under visible light irradiation, the synergy of TiO2 nanoparticles and ZIF-L is in favor of producing hydroxyl radical (·OH) and superoxide radicals (·O2−) that directly leads to the death of bacteria. The sufficient antibacterial activity of ZIF-L@TiO2/fabric (over 95% after six antibacterial assay cycles) ensures the long-term use of the material. At this point, the newly synthesized material gives new sight on preparing other MOFs based composites with photocatalytic antibacterial effect for bacterial issues.

Characteristics of silver-containing titanium-based coating after thermal oxidation

This study has been initiated to form a silver (Ag)-incorporated titanium oxide (TiO2) outermost layer over a medical-grade 316L stainless steel by subsequent applications of cold spray (CS) and thermal oxidation (TO) processes. X-ray diffraction analysis, scanning electron microscopy examination and Raman analysis revealed that TO at 600°C for 60 h in the air formed a 3 μm thick exterior layer composed of the rutile form of titanium oxide and metallic silver over the CS coating fabricated by depositing a mixture of 87 wt.% titanium (Ti), 8 wt.% aluminium (Al) and 5 wt.% silver powder. This exterior layer exhibited superior bioactivity and wear resistance along with a sufficient antibacterial activity, which can further be improved by adjusting the distribution and/or content of silver in its structure.

Preparation of self-assembling Litsea cubeba essential oil/ diphenylalanine peptide micro/nanotubes with enhanced antibacterial properties against Staphylococcus aureus biofilm

The contamination of foodborne pathogens biofilms presents a serious challenge for global food safety, attributed to their rapid diffusion and high antimicrobial resistance. Herein, we demonstrated that Litsea cubeba essential oil (LC-EO) has sufficient antibacterial activity to eradicate S. aureus biofilm. After 4 h treatment of 2 mg/mL LC-EO, the bacterial density inside the biofilm decreased 75.89%. The study on antibiofilm mechanism indicated that during LC-EO treatment, the adhesion of S. aureus was weakened, and the transcription level of ica operon genes (biofilm formation-related) suffered varying degrees of inhibition. In addition, for improving the stability and antibiofilm activity of LC-EO, a LC-EO-loaded peptide micro/nanotubes structure (LC-EO/FNTs) was further prepared in this study via combination with diphenylalanine self-assembly technology. Compared with LC-EO treatment alone, the prepared LC-EO/FNTs showed better eradication effect on S. aureus biofilm with enhanced penetrability across the dense extracellular polymers matrix. Finally, a stable antibacterial effect of LC-EO/FNTs was also obtained with application on different handmade soybean products. This study provides evidence of an innovative strategy for antibiofilm applications of natural antibacterial agents and materials in food matrix.

Controlled release of tetracycline hydrochloride from poly(ω-pentadecalactone-co-ε-caprolactone)/gelatin nanofibers

Development of drug delivery systems is an extensively researched area in biomedical field. In recent years, there is an increasing interest on fabrication of biocompatible nanofibrous drug delivery systems. In the present study, poly(ω-pentadecalactone-co-ε-caprolactone)/gelatin nanofibrous membranes were fabricated for the controlled delivery and release of tetracycline hydrochloride (TCH) antibiotic. Poly(ω-pentadecalactone-co-ε-caprolactone) content provides an originality to the membrane, since it has been synthesized enzymatically previously. Varied amounts of tetracycline hydrochloride including poly(ω-pentadecalactone-co-ε-caprolactone)/gelatin (1:1, v:v) binary polymer blend was electrospun and characterizations (morphological and molecular structure, wettability characteristics, and thermal behavior) were applied to investigate the incorporation of drug molecule. Afterwards, in vitro drug release studies were carried out and mathematical modelling was applied to drug release data in order to clarify the transport mechanism of drug. TCH release profile comprised of an initial burst release in first hour and followed by a sustained release through 14 days which allowed sufficient antibacterial activity against both Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aureus and Bacillus subtilis) bacteria. The presented drug delivery system may be applied as an antibacterial wound dressing device for skin infections.

Comparing the Degradation Potential of Copper(II), Iron(II), Iron(III) Oxides, and Their Composite Nanoparticles in a Heterogeneous Photo-Fenton System.

Heterogeneous photo-Fenton systems offer efficient solutions for the treatment of wastewaters in the textile industry. This study investigated the fabrication and structural characterization of novel peculiar-shaped CuIIO, FeIII2O3, and FeIIO nanoparticles (NPs) compared to the properties of the iron(II)-doped copper ferrite CuII0.4FeII0.6FeIII2O4. The photocatalytic efficiencies of these NPs and the composite of the simple oxides (CuIIO/FeIIO/FeIII2O3) regarding the degradation of methylene blue (MB) and rhodamine B (RhB) as model dyes were also determined. The catalysts were synthesized via simple co-precipitation and calcination technique. X-ray diffractometry (XRD), scanning electron microscopy (SEM), and diffuse reflectance spectroscopy (DRS) were utilized for structural characterization. The structure of CuIIO was bead-like connected into threads, FeIII2O3 was rod-like, while FeIIO pallet-like, with average crystallite sizes of 18.9, 36.9, and 37.1 nm, respectively. The highest degradation efficiency was achieved by CuIIO for RhB and by CuII0.4FeII0.6FeIII2O4 for MB. The CuIIO/FeIIO/FeIII2O3 composite proved to be the second-best catalyst in both cases, with excellent reusability. Hence, these NPs can be successfully applied as heterogeneous photo-Fenton catalysts for the removal of hazardous pollutants. Moreover, the simple metal oxides and the iron(II)-doped copper ferrite displayed a sufficient antibacterial activity against Gram-negative Vibrio fischeri.

Aluminum Metal-Organic Frameworks with Photocatalytic Antibacterial Activity for Autonomous Indoor Humidity Control.

There is an increasing need to maintain the indoor humidity at a comfortable and healthy level without relying on high energy-consuming and potentially germ-infested air-conditioning systems. Water adsorbents exhibiting reversible moisture adsorption/desorption ability as well as sufficient antibacterial activity are highly expected to achieve humidity control in an autonomous and safe way. Metal-organic frameworks (MOFs) featuring high porosity and designability show potential in meeting these requirements in a singular platform. Given the low toxicity and the rich abundance of aluminum in nature, a family of isoreticular Al-terephthalate-based MOFs were systematically evaluated in terms of the static and kinetic water adsorption/desorption and the photocatalytic bacteria-killing behavior. In particular, CAU-1-OH exhibits a desired working range (40-60% RH), a high working capacity (0.41 g g-1), an excellent cycle performance (500 cycles), and a high photocatalytic killing efficiency (99.94%) against Escherichia coli. As a proof of concept, the air filter prepared by coating CAU-1-OH on a commercial nonwoven fabric is capable of buffering against sudden humidity changes caused by the infiltration of outside air and effectively reducing the contamination of bioaerosol or particulate matter. The study significantly advanced the development of next-generation water adsorbents with antibacterial activity for residential humidity control.

Supercritical carbon dioxide application using hydantoin acrylamide for biocidal functionalization of polyester

Biocidal functionalization in polyester fibers is a really tough challenge because of the lack of tethering groups. This study indicated supercritical carbon dioxide application using N-halamine would be an alternative solution for obtaining antibacterial function on the polyester surface. Firstly, N-(2-methyl-1-(4-methyl-2,5-dioxo-imidazolidin-4 yl)propan-2 yl)acrylamide was synthesized and applied to the polyester in supercritical carbon dioxide medium, at 120 °C, 30 MPa for different processing times. The addition of N-halamine on the surface significantly brought antibacterial activity against E. coli. The chlorine loadings showed that 6 -h exposure time was critical to obtain sufficient antibacterial activity. This treatment caused a reasonable and tolerable loss in color and mechanical properties. But, the durability to abrasion, stability, and rechargeability of oxidative chlorine, and the durability of N-halamine on the surface were remarkably good. Conclusively, it can be available to work on polyester surfaces with resource-efficient and eco-friendly supercritical carbon dioxide technique for getting more functionalization and modification.

Fiber Structure, Tensile Behavior and Antibacterial Activity of Polylactide/Poly(butylene terephthalate) Bicomponent Fibers Produced by High-Speed Melt-Spinning

Various types of bicomponent fibers composed of polylactide (PLA) and poly(butylene terephthalate) (PBT) with different molecular weights, arranging the polymers separately in the skin or core, were produced by high-speed melt-spinning. The bicomponent spinning, arranging the PLA with high molecular weight (melt flow rate =1.9 g/10 min, L-lactide content = 98.7%) in the skin and the PBT with low molecular weight (IV = 0.835–0.865 dL/g) in the core, resulted in orientation-induced crystallization in the PLA component at the spinning speed of 2 km/min. This crystallization effect was ascribed to a chain-extending treatment applied to the original PLA (MFR = 4.0 g/10 min) to increase its molecular weight. By the treatment the PLA could crystallize when spun even at 1 km/min in its single-component spinning. On the other hand, the bicomponent spinning system interfered with the orientation-induced crystallization of PBT in the core. As a result, the critical spinning speed needed to generate the orientation-induced crystallization in the core PBT was elevated to 4 km/min. The inferior tensile behavior of the bicomponent fibers, as compared to the single-component PLA or PBT fibers, suggested poor compatibility between PLA and PBT. Transesterification reactions rarely occurred at the interface of the two polymers. The bicomponent fibers prepared from high molecular weight PLA and low molecular weight PBT, however, showed sufficient antibacterial activity and physical properties to be suitable for designing medical clothing materials.

Green approach for fabrication of a novel Zn(II) supramolecular compound as new precursor to produce nano-sized Zinc(II) oxide: Crystallography, topology, Hirshfeld Surface Analysis and biological activities

Mononuclear Zinc (II) compound –based nano-structure with [Zn(L)2(CH3COO)2] {as compound 1} formulation was synthesized by reacting ligand 2-Amino-3-Methyl pyridine with Zinc (II) acetate dihydrate and potassium iodide via sonochemical method and characterized by scanning electron microscopy (SEM), X-ray powder diffraction (XRPD), infrared spectroscopy (IR) and elemental analyses. Single crystal X-ray diffraction was used to determine the structure of compound 1. The Zn(II) cation has a distorted tetrahedral environment composed of two nitrogen atoms from two 2-amino-3-methyl pyridine ligands and two oxygen atoms from two acetate groups. The topological analysis demonstrated that the topology of compound 1 was 1,2,3,4,4M12–1. The Hirshfeld Surface Analysis (HSA) of the crystal packing of compound 1 was discussed in detail to evaluate the interactions among the crystal packing. Thermal stability of the crystal and nano-structures of compound 1 was investigated using thermal gravimetric analyses (TGA) and differential scanning calorimetry (DSC). Calcination of nano-structures of compound 1 at 550 °C produced zinc(II) oxide, which was subsequently characterized using scanning electron microscopy (SEM), X-ray powder diffraction (XRD) and IR spectroscopy. Two strains of gram-negative bacteria (Escherichia coli) and gram-positive bacteria (Staphylococcus aureus) were cultured in the presence of nano-structures of compound 1 to assess their biological activities. This compound displayed sufficient antibacterial activity in an abiotic environment. Cytotoxicity assays of the crystal and nano-structure of compound 1 were performed on L929 human cells. These compounds showed no toxic effect.

Deciphering the Molecular Recognition Mechanism of Multidrug Resistance Staphylococcus aureus NorA Efflux Pump Using a Supervised Molecular Dynamics Approach.

The use and misuse of antibiotics has resulted in critical conditions for drug-resistant bacteria emergency, accelerating the development of antimicrobial resistance (AMR). In this context, the co-administration of an antibiotic with a compound able to restore sufficient antibacterial activity may be a successful strategy. In particular, the identification of efflux pump inhibitors (EPIs) holds promise for new antibiotic resistance breakers (ARBs). Indeed, bacterial efflux pumps have a key role in AMR development; for instance, NorA efflux pump contributes to Staphylococcus aureus (S. aureus) resistance against fluoroquinolone antibiotics (e.g., ciprofloxacin) by promoting their active extrusion from the cells. Even though NorA efflux pump is known to be a potential target for EPIs development, the absence of structural information about this protein and the little knowledge available on its mechanism of action have strongly hampered rational drug discovery efforts in this area. In the present work, we investigated at the molecular level the substrate recognition pathway of NorA through a Supervised Molecular Dynamics (SuMD) approach, using a NorA homology model. Specific amino acids were identified as playing a key role in the efflux pump-mediated extrusion of its substrate, paving the way for a deeper understanding of both the mechanisms of action and the inhibition of such efflux pumps.

Polymethylmethacrylatebased antibacterial coating in vitro and in vivo

Nowadays, the infection recurrence rate in osteomyelitis is still high. New hardware not only allowing one to stabilize bone fragments, but also having antibacterial activity seems to be an extremely useful and promising task. The goal of the study was to assess the effectiveness of use of an antibacterial coating based on polymethylmethacrylate cement in experiment and in infected nonunions of long tubular bones of the lower limbs. Bone cement-based coatings impregnated with antibiotics were formed on titanium plates. A plate rinse was carried out; antibiotic concentrations in the rinsed solutions were estimated by a serial broth microdilution method. The antibacterial activity of control and rinsed samples against the antibiotic-sensitive and multiple-antibiotic-resistant Staphylococcus aureus and Pseudomonas aeruginosa strains was estimated by a bilayer agar method. Clinical part. The study included 70 patients divided into 2 groups: osteosynthesis with antibacterial-coated interlocking nail (40 patients, main group) and osteosynthesis with an external fixation device (30 patients, control group) comparable in age, sex and disease duration. The effectiveness of the antibacterial coating was analyzed by the duration of systemic use of antibiotics and infection recurrence rate. The concentrations of meropenem and phosphomycin in the rinsed solutions obtained at one-fold and two-fold treatments were sufficient to suppress the growth of control strains. Vancomycin-containing samples possessed sufficient antibacterial activity against both methicillin-sensitive (MSSA) and methicillin-resistant (MRSA) S. aureus strains, double rinse of the samples eliminated their bactericidal properties. The duration of systemic antibacterial therapy in the main group was statistically significantly lower than in the control group (U = 77.5, p < 0.001), and in the main group the infection recurrence rate was lower than 32.5 % vs. 86.7 % (χ2 = 20.39, p < 0.001). The PMMA-based coating impregnated with phosphomycin, meropenem or vancomycin possesses sufficient and long-lasting antibacterial activity, mainly against antibiotic-sensitive strains. An adequate use of such a coating in clinical practice allows one to obtain the desired result of treatment.

Antioxidant, Anticancer, Antimicrobial, and Antibiofilm Properties of the Culinary-Medicinal Fairy Ring Mushroom, Marasmius oreades (Agaricomycetes).

This study is based on the phenolic composition and the antioxidant, anticancer, antimicrobial, and antibiofilm activities of the edible mushroom Marasmius oreades from Turkey. The phenolic composition of an M. oreades ethanol extract was measured by using the Folin-Ciocalteu method, aluminium chloride colorimetry, and ultraperformance liquid chromatography. The antioxidant activity was evaluated on the basis of DPPH radical scavenging activity. The effect of the M. oreades ethanol extract was also screened in order to determine glutathione-S-transferase, glutathione peroxidase, catalase, and superoxide dismutase enzyme activities. The antimicrobial activity of the mushroom extract was evaluated by using well diffusion and was based on the minimum inhibitory concentration. In addition, the antibiofilm potential of M. oreades was analyzed against Gram-positive and -negative bacteria. Finally, the anticancer effects of the mushroom extract were tested on colon (HT-29) and breast (MCF-7 and MDA-MB-231) cancer cell lines by using the MTT assay. The results revealed that the total amount of phenolics in the ethanol extract of M. oreades was 10.990 ± 0.0007 mg gallic acid equivalent/100 g, and the total amount of flavonoids was 1.139 ± 0.0052 mg quercetin equivalent/100 g. The ultraperformance liquid chromatography results indicated that the M. oreades ethanol extract contained various phenolic compounds: catechin, ferulic, gallic acid, and vanillic acid. The M. oreades ethanol extract scavenged about 80% of DPPH free radicals. It did not show any effect on the glutathione-S-transferase, glutathione peroxidase, and catalase enzyme activities, but its maximal concentration (10 mg/mL) increased superoxide dismutase activity (8%). The ethanol extract of M. oreades showed a moderate anticancer effect on the HT-29, MCF-7, and MDA-MB-231 cell lines. Although the ethanolic extract of the mushroom did not show sufficient antibacterial activity, it presented a strong antibiofilm effect against all studied pathogenic strains at the tested concentrations.

Antibacterial Activity of Antibiotic-Impregnated Bone Cement Based Coatings Against Microorganisms with Different Antibiotic Resistance Levels

Purpose — to evaluate the presence and duration of antibiotic activity of antibiotic-impregnated bone cement based coatings samples against antibiotic-sensitive and antibiotic-resistant microorganisms.Material and Methods. Bone cement based coatings impregnated with antibiotics (gentamycin, vancomycin, colistin, meropenem, fosfomycin) are formed on titanium (Ti) plates. A plate rinse was carried out; antibiotic concentrations in the rinsed solutions were estimated by a serial broth microdilution method. Antibacterial activity of the control and rinsed samples against the antibiotic-sensitive and multiple-antibiotic-resistant Staphylococcus aureus and Pseudomonas aeruginosa strains was estimated by a bilayer agar method.Results. The meropenem and fosfomycin concentrations in the rinsed solutions obtained at a one-fold (16 μg/ml for both antibiotics) and two-fold treatment (2 μg/ml for meropenem and 8 μg/ml for fosfomycin) were sufficient to suppress the growth of the control strains. One-fold rinse of samples with colistin eliminated their antibacterial activity completely. The marked activity of the samples with meropenem and fosfomycin persisted against the antibiotic-sensitive P. aeruginosa ATCC 27853 strain after 2 rinse cycles; single-rinsed samples with fosfomycin also maintained the activity against the extensively antibioticresistant P. aeruginosa BP-150 strain. Vancomycin-containing samples possessed the sufficient antibacterial activity against both methicillin-sensitive (MSSA) and methicillin-resistant (MRSA) S. aureus strains; two-fold rinse of the samples eliminated their bactericidal properties.Conclusion. Bone cement based coatings impregnated with fosfomycin and meropenem possess the most marked and long-lasting antibacterial activity, manifested mainly against the antibiotic-sensitive strains.

Combined antimicrobial finishing & dyeing properties of cotton, polyester fabrics and their blends with acid and disperse dyes

This study demonstrates the possibility of enhancing the antibacterial activity and dyeing properties of cotton, polyester and their blended fabrics in one step. These fabrics were treated first with carboxymethyl chitosan (10 g/kg) to impart it antibacterial activity and enhance dye ability at the same time followed by dyeing with acid dyes and disperse dye. Results show an improvement in antibacterial activity and dye ability. It was further noted that, in all cases, the treated fabrics were more susceptible towards Gram positive bacteria (S. aureus) than Gram negative bacteria (E. coli) due to bacteria structure. The treated samples exhibited very sufficient antibacterial activity even after 25 washing cycles through durability test. Modes of interactions were proposed, and surface modification was also confirmed by FT-IR, TGA and SEM analysis.

In situ decoration of silver nanoparticles on single-walled carbon nanotubes by microwave irradiation for enhanced and durable anti-bacterial finishing on cotton fabric

Present communication reports microwave-assisted process to decorate single-walled carbon nanotubes (SWCNTs) with silver nanoparticles (Ag-NPs) to induce excellent and durable anti-bacterial activity in cotton fabric. Pristine SWCNTs were functionalized (f-SWCNTs) through acidic treatment for nucleation, followed by reduction of silver ion by microwave heating to produce Ag-NPs decorated SWCNTs (Ag-SWCNTs). Functionalization and decoration of Ag-NPs on SWCNTs were characterized by FTIR, XRD, RAMAN spectroscopy and FE-SEM. Microwave irradiation time was optimized and it was observed that complete reduction of Ag ions on SWCNTs from its precursor (AgNO3) took place within 40 s of microwave irradiation time. For antibacterial activity measurement and comparison, pristine SWCNTs, Ag-NPs and Ag-SWCNTs composite were individually coated on different cotton fabrics via dip-dry-curing process. Deposition of these particles on cotton fabrics were confirmed by FE-SEM and Raman spectroscopy. Antibacterial property of all coated fabrics was evaluated qualitatively against Staphylococcus aureus (S. aureus) as gram positive and Escherichia coli (E.coli) as gram negative pathogenic bacteria. It was observed that the fabric coated with Ag-SWCNTs show excellent antibacterial activity against both types of bacteria. Sufficient antibacterial activity of Ag-SWCNTs coated fabrics was observed even after 20 washing.

Self-assembling diphenylalanine peptide nanotubes selectively eradicate bacterial biofilm infection

Biofilms present a major problem to industry and healthcare worldwide. Composed of a population of surface-attached microbial cells surrounded by a protective extracellular polysaccharide matrix, they are responsible for increased tolerance to antibiotics, treatment failure and a resulting rise in antimicrobial resistance. Here we demonstrate that self-assembled peptide nanostructures composed of a diphenylalanine motif provide sufficient antibacterial activity to eradicate mature biofilm forms of bacteria widely implicated in hospital infections. Modification of terminal functional groups to amino (–NH2), carboxylic acid (–COOH) or both modalities, and switch to d-isomers, resulted in changes in antibacterial selectivity and mammalian cell toxicity profiles. Of the three peptide nanotubes structures studied (NH2-FF-COOH, NH2-ff-COOH and NH2-FF-NH2), NH2-FF-COOH demonstrated the most potent activity against both planktonic (liquid, free-floating) and biofilm forms of bacteria, possessing minimal mammalian cell toxicity. NH2-FF-COOH resulted in greater than 3 Log10 CFU/mL viable biofilm reduction (>99.9%) at 5 mg/mL and total biofilm kill at 10 mg/mL against Staphylococcus aureus after 24 h exposure. Scanning electron microscopy proved that antibiofilm activity was primarily due to the formation of ion channels and/or surfactant-like action, with NH2-FF-COOH and NH2-ff-COOH capable of degrading the biofilm matrix and disrupting cell membranes, leading to cell death in Gram-positive bacterial isolates. Peptide-based nanotubes are an exciting platform for drug delivery and engineering applications. This is the first report of using peptide nanotubes to eradicate bacterial biofilms and provides evidence of a new platform that may alleviate their negative impact throughout society. Statement of SignificanceWe outline, for the first time, the antibiofilm activity of diphenylalanine (FF) peptide nanotubes. Biofilm bacteria exhibit high tolerance to antimicrobials 10–10,000 times that of free-flowing planktonic forms. Biofilm infections are difficult to treat using conventional antimicrobial agents, leading to a rise in antimicrobial resistance. We discovered nanotubes composed of NH2-FF-COOH demonstrated potent activity against staphylococcal biofilms implicated in hospital infections, resulting in complete kill at concentrations of 10 mg/mL. Carboxylic acid terminated FF nanotubes were able to destroy the exopolysaccharide architecture of staphylococcal biofilms expressing minimal toxicity, highlighting their potential for use in patients. Amidated (NH2-FF-NH2) forms demonstrated reduced antibiofilm efficacy and significant toxicity. These results contribute significantly to the development of innovative antibacterial technologies and peptide nanomaterials.