Effect of Ni and Zn Elements on the Microstructure and Antibacterial Properties of Cu Coatings

2019 ◽  
Vol 142 (1) ◽  
Author(s):  
Khaled S. Al-Athel ◽  
Najat Marraiki ◽  
Abul Fazal M. Arif ◽  
Syed Sohail Akhtar ◽  
Javad Mostaghimi ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Bacterial Adhesion ◽  
316L Stainless Steel ◽  
Coating Layer ◽  
Antibacterial Properties ◽  
Lower Surface ◽  
Distilled Water ◽  
Gram Positive ◽  
Gram Negative ◽  
E Coli

In this work, 316L stainless steel samples were coated with copper (Cu) and German silver (Cu 17%Ni 10%Zn) to investigate the relation between their mechanical and antibacterial behaviors. The mechanical and material characteristics of the samples were studied by looking into the microstructure of the surface and the cross-section of the coatings, the surface roughness, and the adhesion strength between the coating layer and the substrate. The antibacterial behavior is then studied against gram-negative Escherichia coli and gram-positive Staphylococcus aureus. Two experiments were conducted to examine the antibacterial behavior. In the first experiment, the coated samples were covered with distilled water, whereas in the second experiment, the samples were tested without being covered with distilled water. The results show that German silver (Cu 17%Ni 10%Zn) had a higher antibacterial rate than copper (Cu) by around 10% for both gram-negative E. coli and gram-positive S. aureus. The reason is because a smoother surface is expected to limit the bacterial adhesion in most cases, and the German silver samples have a lower surface roughness (Ra) due to the higher thermal expansion value of zinc (Zn) compared with copper (Cu). A more in-depth look into the effect of various thickness of the coating with alloying elements (in this case nickel and zinc) on the antibacterial rate would be of great interest.

scholarly journals Dose-Dependent Antimicrobial Activity of Silver Nanoparticles on Polycaprolactone Fibers against Gram-Positive and Gram-Negative Bacteria

2017 ◽  
Vol 2017 ◽  
pp. 1-9 ◽  
Author(s):  
Erick Pazos-Ortiz ◽  
Jose Hafid Roque-Ruiz ◽  
Efrén Amador Hinojos-Márquez ◽  
Juan López-Esparza ◽  
Alejandro Donohué-Cornejo ◽  
...  
Keyword(s):  
Antimicrobial Activity ◽  
Silver Nanoparticles ◽  
Metallic Nanoparticles ◽  
Antibacterial Properties ◽  
Electrospinning Process ◽  
Drug Resistant ◽  
Gram Positive ◽  
Gram Negative ◽  
E Coli ◽  
Dose Dependent

The adhesion ability and adaptability of bacteria, coupled with constant use of the same bactericides, have made the increase in the diversity of treatments against infections necessary. Nanotechnology has played an important role in the search for new ways to prevent and treat infections, including the use of metallic nanoparticles with antibacterial properties. In this study, we worked on the design of a composite of silver nanoparticles (AgNPS) embedded in poly-epsilon-caprolactone nanofibers and evaluated its antimicrobial properties against various Gram-positive and Gram-negative microorganisms associated with drug-resistant infections. Polycaprolactone-silver composites (PCL-AgNPs) were prepared in two steps. The first step consisted in the reduction in situ of Ag+ions using N,N-dimethylformamide (DMF) in tetrahydrofuran (THF) solution, and the second step involved the simple addition of polycaprolactone before electrospinning process. Antibacterial activity of PCL-AgNPs nanofibers againstE. coli,S. mutans,K. pneumoniae,S. aureus,P. aeruginosa, andB. subtiliswas evaluated. Results showed sensibility ofE. coli,K. pneumoniae,S. aureus, andP. aeruginosa, but not forB. subtilisandS. mutans. This antimicrobial activity of PCL-AgNPs showed significant positive correlations associated with the dose-dependent effect. The antibacterial property of the PCL/Ag nanofibers might have high potential medical applications in drug-resistant infections.

scholarly journals Membrane Damage and Microbial Inactivation by Chlorine in the Absence and Presence of a Chlorine-Demanding Substrate

2005 ◽  
Vol 71 (9) ◽  
pp. 5022-5028 ◽  
Author(s):  
R. Virto ◽  
P. Mañas ◽  
I. Álvarez ◽  
S. Condon ◽  
J. Raso
Keyword(s):  
Organic Matter ◽  
Cytoplasmic Membrane ◽  
Membrane Damage ◽  
Microbial Inactivation ◽  
Distilled Water ◽  
Survival Curves ◽  
Gram Positive ◽  
Gram Negative ◽  
Cell Inactivation ◽  
E Coli

ABSTRACT The relationship between cell inactivation and membrane damage was studied in two gram-positive organisms, Listeria monocytogenes and Bacillus subtilis, and two gram-negative organisms, Yersinia enterocolitica and Escherichia coli, exposed to chlorine in the absence and presence of 150 ppm of organic matter (Trypticase soy broth). L. monocytogenes and B. subtilis were more resistant to chlorine in distilled water. The addition of small amounts of organic matter to the chlorination medium drastically increased the resistance of both types of microorganisms, but this effect was more marked in Y. enterocolitica and E. coli. In addition, the survival curves for these microorganisms in the presence of organic matter had a prolonged shoulder. Sublethal injury was not detected under most experimental conditions, and only gram-positive cells treated in distilled water showed a relevant degree of injury. The exposure of bacterial cells to chlorine in distilled water caused extensive permeabilization of the cytoplasmic membrane, but the concentrations required were much higher than those needed to inactivate cells. Therefore, there was no relationship between the occurrence of membrane permeabilization and cell death. The addition of organic matter to the treatment medium stabilized the cytoplasmic membrane against permeabilization in both the gram-positive and gram-negative bacteria investigated. Exposure of E. coli cells to the outer membrane-permeabilizing agent EDTA increased their sensitivity to chlorine and caused the shoulders in the survival curves to disappear. Based on these observations, we propose that bacterial envelopes could play a role in cell inactivation by modulating the access of chlorine to the key targets within the cell.

Structure-Activity Relationship and Antimicrobial Evaluation of N-Phenylpyrazole Curcumin Derivatives

2020 ◽  
Vol 16 (4) ◽  
pp. 481-488
Author(s):  
Heli Sanghvi ◽  
Satyendra Mishra
Keyword(s):  
Antibacterial Activity ◽  
Gram Negative Bacteria ◽  
Pyrazole Derivatives ◽  
Gram Positive ◽  
Gram Negative ◽  
E Coli ◽  
Curcumin Derivatives ◽  
Structure Activity ◽  
Electron Donating Groups ◽  
Derivatives Of

Background: Curcumin, one of the most important pharmacologically significant natural products, has gained significant consideration among scientists for decades since its multipharmacological activities. 1, 3-Dicarbonyl moiety of curcumin was found to be accountable for the rapid degradation of curcumin molecule. The aim of present work is to replace 1, 3-dicarbonyl moiety of curcumin by pyrazole and phenylpyrazole derivatives with a view to improving its stability and to investigate the role of substitution in N-phenylpyrazole curcumin on its antibacterial activity against both Gram-positive as well as Gram-negative bacteria. Methods: Pyrazole derivatives of curcumin were prepared by heating curcumin with phenyhydrazine/ substituted phenyhydrazine derivatives in AcOH. The residue was purified by silica gel column chromatography. Structures of purified compounds were confirmed by 1H NMR and Mass spectroscopy. The synthesized compounds were evaluated for their antibacterial activity by the microdilution broth susceptibility test method against gram positive (S. aureus) and gram negative (E. coli). Results: Effects of substitution in N-phenylpyrazole curcumin derivatives against S. aureus and E. coli were studied. The most active N-(3-Nitrophenylpyrazole) curcumin (12) exhibits twenty-fold more potency against S. aureus (MIC: 10μg/mL)) and N-(2-Fluoroophenylpyrazole) curcumin (5) fivefold more potency against E. coli (MIC; 50 μg/mL) than N-phenylpyrazole curcumin (4). Whereas, a remarkable decline in anti-bacterial activity against S. aureus and E. coli was observed when electron donating groups were incorporated in N-phenylpyrazole curcumin (4). Comparative studies of synthesized compounds suggest the effects of electron withdrawing and electron donating groups on unsubstituted phenylpyrazole curcumin (4). Conclusion: The structure-activity relationship (SAR) results indicated that the electron withdrawing and electron donating at N-phenylpyrazole curcumin played key roles for their bacterial inhibitory effects. The results of the antibacterial evaluation showed that the synthesized pyrazole derivatives of curcumin displayed moderate to very high activity in S. aureus. In conclusion, the series of novel curcumin derivatives were designed, synthesized and tested for their antibacterial activities against S. aureus and E. coli. Among them, N-(3-Nitrophenylpyrazole curcumin; 12) was most active against S. aureus (Gram-positive) and N-(2-Fluoroophenylpyrazole) curcumin (5) against E. coli (Gram-negative) bacteria.

Green synthesised silver nanoparticles incorporated electrospun poly(methyl methacrylate) nanofibers with different architectures for ophthalmologic alternatives

2021 ◽  
Vol 36 (2) ◽  
pp. 93-110
Author(s):  
Princy Philip ◽  
Tomlal Jose ◽  
Sarath KS ◽  
Sunny Kuriakose
Keyword(s):  
Silver Nanoparticles ◽  
Methyl Methacrylate ◽  
Antibacterial Properties ◽  
Analytical Techniques ◽  
Morphological Properties ◽  
Gram Positive ◽  
Gram Negative ◽  
Poly Methyl Methacrylate ◽  
Antimicrobial Studies ◽  
Eye Problems

Silver nanoparticles with 5–10 nm diameters are synthesised using Couroupita guianensis flower extract. The synthesised silver nanoparticles found to show good antimicrobial activity against gram negative and gram positive bacteria. Poly(methyl methacrylate) nanofibers with pristine, surface roughened and coaxial hollow forms are prepared by electrospinning. The structural and morphological properties of these pure and structurally modified poly(methyl methacrylate) nanofibers are evidenced by various analytical techniques. The antimicrobial studies of poly(methyl methacrylate) nanofibers having different architectures incorporated with silver nanoparticles are carried out. It is found that, all the three forms of poly(methyl methacrylate) nanofibers incorporated with silver nanoparticles show antibacterial properties against both gram positive and gram negative bacteria. Among these, surface roughened poly(methyl methacrylate) nanofibers incorporated with silver nanoparticles show highest antibacterial activity than the other two structural forms. The present study offers an alternative to the existing optical lenses. People especially those who suffer from eye problems can protect their eyes in a better way from infectious agents by wearing optical lens made from C. guianensis stabilised silver nanoparticles incorporated poly(methyl methacrylate) nanofibers than that made from pure poly(methyl methacrylate) nanofibers or films.

scholarly journals Asymptomatic Bacteriuria among Pregnant Women Attending Tertiary Care Hospital in Lucknow, India

2021 ◽  
pp. 1-8
Author(s):  
Naimshree Sonkar ◽  
Malay Banerjee ◽  
Suman Gupta ◽  
Absar Ahmad
Keyword(s):  
Haemoglobin Level ◽  
Pregnant Women ◽  
Antimicrobial Susceptibility ◽  
Tertiary Care Hospital ◽  
Tertiary Care ◽  
Asymptomatic Bacteriuria ◽  
Care Hospital ◽  
Gram Positive ◽  
Gram Negative ◽  
E Coli

Introduction: Asymptomatic bacteriuria (ASB) is the presence of actively multiplying bacteria within the urinary tract with absence of any symptoms, resulting in adverse pregnancy outcomes. This research study was done in order to review prevalence, antimicrobial susceptibility profile, and factors associated with ASB occurring in female patients who are pregnant and being treated at a tertiary care hospital in Lucknow, India. Method and Materials: This is a cross-sectional study done among 216 pregnant women attending a hospital for antenatal check-ups. Clean catch midstream urine samples were collected and examined microscopically, and semi-quantitative culture was done on blood agar and MacConkey agar. Isolates were identified by colony morphology and biochemical tests, and antimicrobial susceptibility testing was done by using the Kirby-Bauer method. Results: Of the 216 pregnant women, 36 (16.7%) tested positive for ASB. The female gestational period, haemoglobin level, and BMI were significantly associated with ASB. Logistic regression also showed that higher haemoglobin level was less likely to ASB (AOR = 0.42, 95% confidence interval: 0.202–0.88, p = 0.021). The predominant and usual isolates were E. coli (n = 22, 61.1%), followed by Cons (n = 6, 16.7%), and S. aureus (3, 8.3%). All Gram-negative isolates were mostly sensitive to most of the drugs like piperacillin-tazobactam, cefepime, nitrofurantoin, and meropenem but were 100% resistant to ampicillin. Similarly, Gram-positive isolates were sensitive to ampicillin, vancomycin, linezolid, and nitrofurantoin but 100% resistant to co-trimoxazole. Conclusion: The present study shows the existence of ASB was 16.7% among women who are pregnant. Pregnancy duration, haemoglobin level, and BMI were significantly associated with ASB. The isolates identified more frequently were E. coli (61.16%), Cons (16.7%), and S. aureus (8.3%). All isolates which were Gram-negative were mostly sensitive to most of the drugs but were 100% resistant to ampicillin. Similarly, Gram-positive isolates were sensitive to most of the drugs but 100% resistant to co-trimoxazole.

Preparation of bioactive and antibacterial PMMA-based bone cement by modification with quaternary ammonium and alkoxysilane

2021 ◽  
pp. 088532822110044
Author(s):  
Haiyang Wang ◽  
Toshinari Maeda ◽  
Toshiki Miyazaki
Keyword(s):  
Antibacterial Activity ◽  
Methyl Methacrylate ◽  
Bone Cement ◽  
Setting Time ◽  
Antibacterial Properties ◽  
The Body ◽  
Apatite Formation ◽  
Gram Positive ◽  
E Coli ◽  
Gram Positive Bacteria

Bone cement based on poly(methyl methacrylate) (PMMA) powder and methyl methacrylate (MMA) liquid is a very popular biomaterial used for the fixation of artificial joints. However, there is a risk of this cement loosening from bone because of a lack of bone-bonding bioactivity. Apatite formation in the body environment is a prerequisite for cement bioactivity. Additionally, suppression of infection during implantation is required for bone cements to be successfully introduced into the human body. In this study, we modified PMMA cement with γ-methacryloxypropyltrimetoxysilane and calcium acetate to introduce bioactive properties and 2-( tert-butylamino)ethyl methacrylate (TBAEMA) to provide antibacterial properties. The long-term antibacterial activity is attributed to the copolymerization of TBAEMA and MMA. As the TBAEMA content increased, the setting time increased and the compressive strength decreased. After soaking in simulated body fluid, an apatite layer was detected within 7 days, irrespective of the TBAEMA content. The cement showed better antibacterial activity against Gram-negative E. Coli than Gram-positive bacteria; however, of the Gram-positive bacteria investigated, B. subtilis was more susceptible than S. aureus.

Antibacterial Properties of CdO Nano-Cubes Synthesized via Microwave Method

2013 ◽  
Vol 829 ◽  
pp. 294-298 ◽  
Author(s):  
Mehrdad Rashidzadeh
Keyword(s):  
Structural Information ◽  
Cadmium Oxide ◽  
Antibacterial Properties ◽  
Antibacterial Activities ◽  
Raw Material ◽  
X Ray Diffraction ◽  
Gram Negative ◽  
E Coli ◽  
Oxidation Reduction ◽  
Cdo Nanoparticles

High purity Cadmium (Cd) metal was used as raw material and placed in a microwave susceptor. an evaporation/oxidation process occurs under exposure to microwave in less than 2 minutes. Then, Evaporated cadmium reacted with oxygen and cadmium oxide was collected on the inner surface of a glassy container that was placed a few centimeters above the susceptor. Morphological and structural information of As-synthesized CdO nanopowder, were investigated via SEM and X-ray diffraction (XRD) spectroscopy. The antibacterial activities of different concentration of the CdO nanoparticles were tested by treating Escherichia coli (Gram negative) cultures with CdO nanoparticles. The Study indicates that cadmium oxide nanoparticles show effective antibacterial activity toward the gram-negative bacterium E. coli. Electrochemical properties of as-synthesized powder were investigated via linear and two vertex cyclic voltammetery in the presence of ethanol, a pair of Oxidation/reduction peaks were achieved.

Effectiveness of ZnO Nano Particles against the Foodborne Microbial Pathogens E. coli and S. aureus

2020 ◽  
Vol 15 (2) ◽  
pp. 87-94
Keyword(s):  
Antimicrobial Agents ◽  
Inhibitory Concentration ◽  
Antimicrobial Effect ◽  
Nano Particles ◽  
Microbial Pathogens ◽  
Gram Positive ◽  
Gram Negative ◽  
E Coli ◽  
Antimicrobial Susceptibility Tests ◽  
Susceptibility Tests

In this work, various concentrations of ZnO nano particles, prepared by the coprecipitation method with a size range of 47-68 nm, have been investigated as antimicrobial agents. Dilution antimicrobial susceptibility tests were carried out on two kinds of microbes (Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli) according to the standard method recommended by Clinical and Laboratory Standards Institute, CLSI-2015-M07-A10. The results showed that the antimicrobial effect is larger, the higher the concentration of ZnO nano particles in solution. It was also found that Gram-positive microbes are more sensitive to ZnO nano particles when compared with the Gram-negative ones. The minimum inhibitory concentration (MIC) for E. coli was found to be 50 mg/mL while that for S. aureus was 25 mg/mL. The minimum bactericidal concentration (MBC) was 1600 mg/mL for E. coli and 800 mg/mL for S. aureus.

scholarly journals Organization of the Flagellar Switch Complex ofBacillus subtilis

2018 ◽  
Vol 201 (8) ◽  
Author(s):  
Elizabeth Ward ◽  
Eun A Kim ◽  
Joseph Panushka ◽  
Tayson Botelho ◽  
Trevor Meyer ◽  
...  
Keyword(s):  
Bacillus Subtilis ◽  
Protein Interaction ◽  
Protein Complex ◽  
Cross Linking ◽  
Gram Positive ◽  
Gram Negative ◽  
Content Type ◽  
E Coli ◽  
Middle Domain ◽  
Flagellar Rotation

ABSTRACTWhile the protein complex responsible for controlling the direction (clockwise [CW] or counterclockwise [CCW]) of flagellar rotation has been fairly well studied inEscherichia coliandSalmonella, less is known about the switch complex inBacillus subtilisor other Gram-positive species. Two component proteins (FliG and FliM) are shared betweenE. coliandB. subtilis, but in place of the protein FliN found inE. coli, theB. subtiliscomplex contains the larger protein FliY. Notably, inB. subtilisthe signaling protein CheY-phosphate induces a switch from CW to CCW rotation, opposite to its action inE. coli. Here, we have examined the architecture and function of the switch complex inB. subtilisusing targeted cross-linking, bacterial two-hybrid protein interaction experiments, and characterization of mutant phenotypes. In major respects, theB. subtilisswitch complex appears to be organized similarly to that inE. coli. The complex is organized around a ring built from the large middle domain of FliM; this ring supports an array of FliG subunits organized in a similar way to that ofE. coli, with the FliG C-terminal domain functioning in the generation of torque via conserved charged residues. Key differences fromE. coliinvolve the middle domain of FliY, which forms an additional, more outboard array, and the C-terminal domains of FliM and FliY, which are organized into both FliY homodimers and FliM heterodimers. Together, the results suggest that the CW and CCW conformational states are similar in the Gram-negative and Gram-positive switches but that CheY-phosphate drives oppositely directed movements in the two cases.IMPORTANCEFlagellar motility plays key roles in the survival of many bacteria and in the harmful action of many pathogens. Bacterial flagella rotate; the direction of flagellar rotation is controlled by a multisubunit protein complex termed the switch complex. This complex has been extensively studied in Gram-negative model species, but little is known about the complex inBacillus subtilisor other Gram-positive species. Notably, the switch complex in Gram-positive species responds to its effector CheY-phosphate (CheY-P) by switching to CCW rotation, whereas inE. coliorSalmonellaCheY-P acts in the opposite way, promoting CW rotation. In the work here, the architecture of theB. subtilisswitch complex has been probed using cross-linking, protein interaction measurements, and mutational approaches. The results cast light on the organization of the complex and provide a framework for understanding the mechanism of flagellar direction control inB. subtilisand other Gram-positive species.

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