717 research outputs found
ANTIBACTERIAL, IN VITRO CYTOTOXIC, AND ANTIOXIDANT ACTIVITIES OF ELECTROLYZED OXIDIZING/REDUCING WATER
Objective: Electrolyzed oxidizing/reducing water is popular as health beneficial water in Indonesia. In this study, we examined the level of antibacterial,anticancer, and antioxidant activity of the electrolyzed water.Methods: The efficacy of electrolyzed water produced by Enagic® at six level pH (2.5, 6.0, 7.0, 8.5, 9.0, and 9.5) was investigated. Antibacterialactivity was evaluated using a macrodilution method. The anticancer activity was performed against human breast cancer (T47D) cell lines using3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay. Moreover, the antioxidant activity was determined using antioxidant model,2,2-diphenyl-1picrylhydrazyl radical scavenging activity.Results: The results show that electrolyzed water exhibited antibacterial activity against Propionibacterium acnes and Staphylococcus epidermidis.Among six level pH, electrolyzed water at pH 2.5 showed the highest antibacterial activity. The in vitro cytotoxic activity of electrolyzed water showedpotential moderate cytotoxicity. The activity tends to be higher in alkaline electrolyzed water. However, the electrolyzed water showed free radicalscavenging activity.Conclusion: Electrolyzed water that marked in Indonesia has some potential health benefits. The activity is dependent on pH
Effect of heat treatment on bioelectronic coordinates and antibacterial activities of natural and synthetic clays
Our work consists in studying the effect of the thermal treatment at 900°C of three clays “two anionic clays of synthesis ' Double lamellar hydroxide' Zn3Al-CO3 and Mg3Al-CO3, and another natural cationic: Ghassoul (Gh)”, on their antibacterial and bioelectronic power. Their chemical characteristics such as pH at zero charge point (pHzcp), redox potential (Eh), index of oxidizing/reducing power (rH2), and electrochemical potential to dissipate energy (W), as well as the type of oxide formed as a result of this treatment; were also determined. The materials were characterized by powder X-ray diffraction (XRD), Fourier transform infrared spectrometry (FTIR), and scanning electron microscopy (SEM). Antibacterial activity was tested for four bacteria: two Gram positive (Staphylococcus aureus, Enterococcus faecalis) and two Gram negative (Escherichia coli, Salmonella spp). The antibacterial power of the three clays was evaluated by their minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC), using the microtiter plate technique. The results showed that the pHzcp, rH2, W and antibacterial power of the two lamellar double hydroxides increased as a result of heat treatment. While the test on the heat treated cationic clay showed an opposite result. It thus appears that the changes in the physicochemical and electrochemical characteristics of the clays following their calcination at 900°C; are at the origin of the change in their antibacterial powe
The efficacy of chlorine-based disinfectants against planktonic and biofilm bacteria for decentralised point-of-use drinking water
Chlorine solutions are used extensively for the production of biologically safe drinking water. The capability of point-of-use [POU] drinking water treatment systems has gained interest in locations where centralised treatment systems and distribution networks are not practical. This study investigated the antimicrobial and anti-biofilm activity of three chlorine-based disinfectants (hypochlorite ions [OCl-], hypochlorous acid [HOCl] and electrochemically activated solutions [ECAS]) for use in POU drinking water applications. The relative antimicrobial activity was compared within bactericidal suspension assays (BS EN 1040 and BS EN 1276) using Escherichia coli. The anti-biofilm activity was compared utilising established sessile Pseudomonas aeruginosa within a Centre for Disease Control [CDC] biofilm reactor. HOCl exhibited the greatest antimicrobial activity against planktonic E. coli at >50 mg L−1 free chlorine, in the presence of organic loading (bovine serum albumen). However, ECAS exhibited significantly greater anti-biofilm activity compared to OCl- and HOCl against P. aeruginosa biofilms at ≥50 mg L−1 free chlorine. Based on this evidence disinfectants where HOCl is the dominant chlorine species (HOCl and ECAS) would be appropriate alternative chlorine-based disinfectants for POU drinking water applications
BIOLOGICAL IMPLICATIONS OF THE REACTIONS OF THIOCYANATE (SCN
Hypochlorous acid (HOCl) is one of the major neutrophil-derived oxidants used to kill invading pathogens. However, excess or misplaced production of HOCl can damage host tissue as it reacts indiscriminately with biological molecules such as amino acids. Chloramines are a major product of the reaction between HOCl and amino acids. As they decompose, protein-bound chloramines can permanently damage proteins by altering their structures and function. Thiocyanate (SCN-) reacts efficiently with HOCl and thus is able to limit its propensity to inflict host tissue damage. The concentration of SCN- in human physiologic fluids varies depending on the source of fluid and the individuals dietary and smoking habits. For example, normal human blood plasma has micromolar levels of SCN- while the oral cavity has millimolar concentrations.The first chapter of this dissertation covers the objectives of the research and the introduction of the important themes. The second chapter summarizes the experimental methods and the analytical techniques used to conduct the research. The third chapter of this dissertation is focused on the reaction of SCN- with chloramines. We found that SCN- reacts efficiently with chloramines in small molecules, in proteins, and in Escherichia coli cells to give OSCN- and the parent amine. We also observed that chloramines react faster with OSCN- than SCN-. This suggests that the reductions of chloramines by SCN- and OSCN- have potential biological significance as they may repair some of the damage infected by HOCl on proteins.Under slightly acidic pH conditions, chloramines disproportionate to dichloramines. In the fourth chapter, the reactivity of dichloramines towards thiols was examined. We found that at equimolar concentrations, the dichloramines react much faster with thiols than monochloramines. Chlorotaurine reacts with thiols with a (pH-dependent) pseudo-second order rate constant of 102 M-1s-1 while the rate constant for dichlorotaurine is 106 M-1s-1 at pH 7.4. These results suggest that the more stable dichloramines (e.g. those on lysine residues and on taurine) may be playing a role, at least in part, in the killing of phagocytosed bacteria.The fifth chapter of this dissertation evaluates the biological significance of the reaction of SCN- with chloramines. To achieve this goal, we investigated the extent to which SCN- restored the activity of glutathione reductase (GR) and also how it affected the population of viable A549 lung cancer cells after treatment with HOCl. Under certain conditions, we found that approximately half of GR activity that was inactivated by a large molar excess of HOCl was recovered after incubation with SCN-. We speculate that the cysteine active site of the protein was protected from irreversible over-oxidation by its hydrophobicity. The observed reversibility upon reaction with thiocyanate is attributed to a chlorinated key histidine. The viability studies of A549 cells incubated with HOCl for 20 min and then with SCN- show a significant increase in the proportion of live cells and a decrease in the proportion of necrotic cells. We surmise based on these results that early SCN- intervention (20 min) after the exposure of A549 cells to low concentrations of HOCl can repair and reverse some of the damage. Overall, the results of the investigation described in this dissertation indicate that SCN- may play a more active role in quenching chloramines in vivo than has been previously appreciated
Toward Sustainable Tackling of Biofouling Implications and Improved Performance of TFC FO Membranes Modified by Ag-MOF Nanorods
In this work, nanorods with high antibacterial properties were synthesized with silver acetate as the metal source and 2-aminoterephthalic acid as the organic linker and were then embedded into thin-film composite (TFC) membranes to amend their performance as well as to alleviate biofouling. Silver metal-organic framework (Ag-MOF) nanorods with a length smaller than 40 nm were incorporated within the polyamide thin selective layer of the membranes during interfacial polymerization. The interaction of the synthesized nanorods with the polyamide was favored because of the presence of amine-containing functional groups on the nanorod's surface. The results of X-ray photoelectron spectroscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and atomic force microscopy characterizations proved the presence of Ag-MOF nanorods in the selective layer of thin-film nanocomposite (TFN) membranes. TFN membranes demonstrated improved water permeance, salt selectivity, and superior antibacterial properties. Specifically, the increased hydrophilicity and antibacterial potential of the TFN membranes led to a synergetic effect toward biofouling mitigation. The number of live bacteria attached to the surface of the neat TFC membrane decreased by more than 92% when a low amount of Ag-MOF nanorods (0.2 wt %) was applied. Following contact of the TFN membrane surface with Escherichia coli and Staphylococcus aureus, full inactivation, and degradation of bacteria cells were observed with microscopy, colony-forming unit tests, and disc inhibition zone analyses. This result translated to a negligible amount of the biofilm formed on the active layer. Indeed, the incorporation of Ag-MOF nanorods decreased the metal-ion release rate and therefore provided prolonged antibacterial performance
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Layer-by-Layer Antimicrobial N-Halamine Polymer Coatings for Food Contact Materials
Cross contamination during food processing represents a risk for public health and financial burden. Surface modification of food contact materials to render them antimicrobial can be effective against such risk. The objective of the present work was to develop antimicrobial coatings with the potential to be applied in a variety of food contact materials. The polymer coatings developed became antimicrobial by incorporation of a type of chlorinated compounds called N-halamines, capable of regenerating their antimicrobial activity.
Two layer-by-layer (LbL) assembly surface modification procedures were followed. In the first procedure, bilayers of branched polyethyleneimine (PEI) and poly(acrylic acid) (PAA) were applied onto stainless steel and polyethylene (PE). As the number of bilayers increased, so did the number of N-halamines the coatings were able to harbor. Increasing the number of bilayers also translated into greater antimicrobial efficacy against Listeria monocytogenes. The maximum level of inactivation was \u3e 99.999%, comparable to the equivalent concentration of free chlorine. Inactivation kinetics was also studied. Coatings exhibited a sigmoidal behavior with a slower biocidal effect as compared to free chlorine. The PEI-PAA coating was also challenged against multiple rechlorinations and washing under different levels of pH and exhibited stability and ability to be regenerated.
The preparation of the PEI-PAA coating was time consuming and required expensive crosslinkers. As an alternative method for N-halamine surface modification, two bilayers of PEI and styrene maleic anhydride copolymer (SMA) were coated onto polypropylene (PP). The coating exhibited intrinsic antimicrobial properties against L. monocytogenes due to its cationic nature, able to achieve ~ 3 logarithmic cycles in reduction as prepared, and \u3e 99.999% when chlorinated. No carbodiimide crosslinkers were needed. In addition, the coating didn\u27t result in a significant change in surface energy (P \u3e 0.05). The coating was also challenged against multiple rechlorinations, showing reusability.
The results suggest that the surface modification methods studied possess the potential to be applied on a variety of materials used in food processing to avoid microbial contamination. Future research will focus on developing N-halamine antimicrobial coatings with improved stability and more efficient preparation, and in the development of new antimicrobial N-halamine materials
Potential of Electrolyzed Water as an Alternative Disinfectant Agent in the Fresh-Cut Industry
Water disinfection is one of the most critical processing
steps in fresh-cut vegetable production. Technologies
capable for the efficient disinfection of process water and
recycled water would allow reducing wastewater and have
less impact on the environment. Among the chemical
disinfectants, hypochlorite solutions are still the most widely
used. Electrochemical disinfection of the wash water has been
demonstrated to be effective in eliminating a wide spectrum of
pathogens in process water. Both hypochlorite solutions and
electrochemically produced chlorine compounds, in particular
hypochlorous acid, are effective disinfectants when adequate
doses are used. A new electrochemical process using borondoped
diamond electrodes can generate additional reactive
oxidant species than chlorine and further enhance the
disinfecting capacity. However, there are pros and cons on
the use of one or other disinfectant agents. In this review, the
technological advantages and the limitations of electrolyzed
water, particularly regarding the organic matter content, are
discussed and compared to the use of hypochlorite.Ciencias de la Alimentació
electrolysed water in the food industry as supporting of environmental sustainability
Food safety is a priority for the food industry and to achieve this result a correct plant sanitation programme is of the utmost importance. Among various disinfection techniques, an emerging one is represented by the use of electrolysed water (EW) as the disinfecting agent. The use of EW is compliant with the desire to find alternatives to chlorination and heat treatments, representing a green cleaning alternative to toxic disinfectants. EW is an activated liquid, obtained by passing a diluted saline solution (NaCl, KCl or MgCl2) through an electrolytic cell, thus causing the production from the anode side of electrolysed oxidising water, containing high dissolved oxygen, free chlorine and characterised by a low pH (2.3–2.7) and a high oxidation–reduction potential (ORP > 1,000 mV). At the same time from the cathode side electrolysed reduced water is produced, with high pH (10.0–11.5), high dissolved hydrogen and low ORP (−800 to −900 mV). Unlike other chemical disinfectants, EW is not harmful for skin and mucous membranes and is quite easy to handle. Furthermore, the use of EW is relatively inexpensive and, above all, is a sustainable technique. Currently used sanitisers (e.g. glutaraldehyde, formaldehyde, etc.) are effective, but their adverse effects on the environment are well known. Differently from these chemicals, the use of EW has a reduced impact on the environment and because of its properties, it may find several applications in the food industry. In this work, the characteristics and some EW applications as sustainable sanitation technique applied in the food industry are reported and discussed
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