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Tarakdas Basu - One of the best experts on this subject based on the ideXlab platform.
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a simple fast and cost effective method of synthesis of cupric oxide nanoparticle with promising antibacterial potency unraveling the biological and chemical modes of action
Biochimica et Biophysica Acta, 2015Co-Authors: Ruchira Chakraborty, Raj Kumar Sarkar, Arijit Kumar Chatterjee, U Manju, Asoke P Chattopadhyay, Tarakdas BasuAbstract:Abstract Background Gradual attainment of bacterial resistance to antibiotics led us to develop a robust method of synthesis of stable, colloidal cupric oxide nanoparticle of physiological pH with potential antibacterial action. Methods Cu(II) oxide NP was synthesized by reduction–oxidation of CuCl2, using polyvinyl alcohol as stabilizer. Characteristics and antibacterial activity of the particles were investigated by techniques like UV–Vis spectrophotometry, DLS, AFM, TEM, EDS, FTIR, AAS, agar plating, FACS, gel electrophoresis and XPS. Results The NPs were about 50 nm in size and cubic in shape with two surface plasmon peaks at 266 and 370 nm and had semi-conducting behavior with a band gap of 3.40 and 3.96 eV. About 80% of precursor CuCl2 was converted to NP. The minimum inhibitory and the minimum bactericidal concentrations of CuO-NP were respectively 120 and 160 μg/mL for Escherichia coli and 180 and 195 μg/mL for Staphylococcus aureus in Luria–Bertani medium. In growth media, the NPs got modified by media organics with displacement of the stabilizer PVA molecules. This modified NP (around 240 nm) killed cells by generating ROS, which finally caused membrane lipid per-oxidation and chromosomal DNA degradation in NP-treated cells. Conclusion Reports indicate that we are among the few who had prepared CuO-NP in colloidal form. The antibacterial potency of our particle in growth media was much promising than other reports. Our findings demonstrated that ‘particle-specific’ effect, not ‘ion-specific’ one, was responsible for the NP action. General significance The NP may be used as a Sterilizing Agent in various bioprocesses and as substituent of antibiotics, after thorough toxicological study.
Ruchira Chakraborty - One of the best experts on this subject based on the ideXlab platform.
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a simple fast and cost effective method of synthesis of cupric oxide nanoparticle with promising antibacterial potency unraveling the biological and chemical modes of action
Biochimica et Biophysica Acta, 2015Co-Authors: Ruchira Chakraborty, Raj Kumar Sarkar, Arijit Kumar Chatterjee, U Manju, Asoke P Chattopadhyay, Tarakdas BasuAbstract:Abstract Background Gradual attainment of bacterial resistance to antibiotics led us to develop a robust method of synthesis of stable, colloidal cupric oxide nanoparticle of physiological pH with potential antibacterial action. Methods Cu(II) oxide NP was synthesized by reduction–oxidation of CuCl2, using polyvinyl alcohol as stabilizer. Characteristics and antibacterial activity of the particles were investigated by techniques like UV–Vis spectrophotometry, DLS, AFM, TEM, EDS, FTIR, AAS, agar plating, FACS, gel electrophoresis and XPS. Results The NPs were about 50 nm in size and cubic in shape with two surface plasmon peaks at 266 and 370 nm and had semi-conducting behavior with a band gap of 3.40 and 3.96 eV. About 80% of precursor CuCl2 was converted to NP. The minimum inhibitory and the minimum bactericidal concentrations of CuO-NP were respectively 120 and 160 μg/mL for Escherichia coli and 180 and 195 μg/mL for Staphylococcus aureus in Luria–Bertani medium. In growth media, the NPs got modified by media organics with displacement of the stabilizer PVA molecules. This modified NP (around 240 nm) killed cells by generating ROS, which finally caused membrane lipid per-oxidation and chromosomal DNA degradation in NP-treated cells. Conclusion Reports indicate that we are among the few who had prepared CuO-NP in colloidal form. The antibacterial potency of our particle in growth media was much promising than other reports. Our findings demonstrated that ‘particle-specific’ effect, not ‘ion-specific’ one, was responsible for the NP action. General significance The NP may be used as a Sterilizing Agent in various bioprocesses and as substituent of antibiotics, after thorough toxicological study.
Nicosia S. - One of the best experts on this subject based on the ideXlab platform.
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STERILIZZAZIONE CON MICROONDE DI RIFIUTI SANITARI: DETERMINAZIONE DIRETTA DELL’EFFICACIA DEL PROCESSO
Colorshade Via Via Cristoforo Colombo 7 – 20068 Peschiera Borromeo (MI), 2018Co-Authors: Lanza P., Maida C., Benanti L., Giliberto G., Nicosia S.Abstract:In the sterilization of those Health Care Waste that are marked as possibly infectious, microwaves (MW) have long been proposed as an alternative means to steam. The effectiveness of the operation is assessed determining the fraction that has survived to the Sterilizing Agent of a known starting population of micro-organisms. Customarily, this population is introduced into the waste mass in the form of one or more sealed vials. These make up an artificial environment which is completely under control; but onto it the Sterilizing Agent could a priori behave with higher or lower effectiveness, compared with the loose mass which is directly exposed to it. As far as the traditional steam sterilization has been the only process available, the meaning and representativeness of the micro-organisms’ response in sealed vials have not been questioned. In principle, however, a penetrative physical Sterilizing Agent – as MWs are – could sterilize a standard vial’s content better than would do steam, which will just flow around it. If an operator is about deciding whether to shift to MWs, this success induces him to reduce the energy to feed to the waste mass, compared to that he deemed satisfactory before, when transferred by steam. Since the onset of MW sterilization technique, therefore, a need for validation in the most realistic conditions arose. This demand drives researchers to work out techniques for bacterial count that have no barriers: that is, techniques that count the same tracing cells, but after they, 1) have been freely dispersed in the whole mass; 2) have undergone the same disinfecting actions as the surrounding mass; 3) have been sampled from the mass at the end of the process. It is evident that – in order to gain certainties in phase 2 – two severe uncertainties have been unwillingly introduced as phases 1 and 3. Indeed, the experimental campaign on which this paper reports was aimed at simulating at lab scale the MW sterilization of synthetic waste samples which had been contaminated with known amounts of spores; to get quantitative information on the efficiency and identify the possibly critical steps of the whole procedure. In the 6 different sessions that were run, the operational variables were the waste moisture content (25% – 80%) and the amount of energy supplied as MW; residence time 40 min instead was common to all tests. The temperature patterns were recorded, and at the end the whole mass was washed to detach the spores for following cultivation – count. In this way the critical features of the procedure were identified and ranked by severity. It was foreseen that the procedure would be time-consuming and would require handling of considerable amounts of water and glassware. The experiments showed something more serious: actually, the physiological solution alone – without any surfactant Agent added – is unable to detach quantitatively the spores from the waste chips and the beaker walls. Addition of a few drops of surfactants – as was done by Oliveira et al. (2010) – is thus a technical detail which is critical for the success of the whole treatment – analysis chain. Of course we ought to have the certainty that the surfactant chosen does not interfere with the growing medium and / or the bacterial viability in the plate cultivation following. The loss of viable spores in washing the waste batches was calculated by us: 1) sampling and cultivating 1 ml wash solution coming from the control sample inoculated and not irradiated (called K+); and then, 2) comparing the result with the known inoculum. Regrettably, less than 2% spores were found have been recovered. Under the hypothesis that the washing operation is replicable and is not affected by the “irradiated / non irradiated” condition, the disinfection efficiency was then calculated on K+ number. About the results: the MW reduction of microbial load in irradiated batches was just mediocre (98,2%), short of the prescribed 99,99%. The best result was attained with a sample with 60% moisture and unit power input 272 W, corresponding to a unit input of 350 W kg-1 of sample waste. In principle, MW irradiation will heat up waste mass; and this in turn will contribute to microbial inactivation. Water content has a complex relationship with this phenomenon, since the driest batches interact too weakly, while moistest batches do interact but their moisture use up most of the heat. In this experimental campaign, moisture decreased by around 10-30%; but no reliable correlation is evident
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STERILIZZAZIONE CON MICROONDE DI RIFIUTI SANITARI: DETERMINAZIONE DIRETTA DELL’EFFICACIA DEL PROCESSO
country:IT, 2018Co-Authors: Lanza P., Maida C., Benanti L., Giliberto G., Nicosia S.Abstract:In the sterilization of those Health Care Waste that are marked as possibly infectious, microwaves (MW) have long been proposed as an alternative means to steam. The effectiveness of the operation is assessed determining the fraction that has survived to the Sterilizing Agent of a known starting population of micro-organisms. Customarily, this population is introduced into the waste mass in the form of one or more sealed vials. These make up an artificial environment which is completely under control; but onto it the Sterilizing Agent could a priori behave with higher or lower effectiveness, compared with the loose mass which is directly exposed to it. As far as the traditional steam sterilization has been the only process available, the meaning and representativeness of the micro-organisms\u2019 response in sealed vials have not been questioned. In principle, however, a penetrative physical Sterilizing Agent \u2013 as MWs are \u2013 could sterilize a standard vial\u2019s content better than would do steam, which will just flow around it. If an operator is about deciding whether to shift to MWs, this success induces him to reduce the energy to feed to the waste mass, compared to that he deemed satisfactory before, when transferred by steam. Since the onset of MW sterilization technique, therefore, a need for validation in the most realistic conditions arose. This demand drives researchers to work out techniques for bacterial count that have no barriers: that is, techniques that count the same tracing cells, but after they, 1) have been freely dispersed in the whole mass; 2) have undergone the same disinfecting actions as the surrounding mass; 3) have been sampled from the mass at the end of the process. It is evident that \u2013 in order to gain certainties in phase 2 \u2013 two severe uncertainties have been unwillingly introduced as phases 1 and 3. Indeed, the experimental campaign on which this paper reports was aimed at simulating at lab scale the MW sterilization of synthetic waste samples which had been contaminated with known amounts of spores; to get quantitative information on the efficiency and identify the possibly critical steps of the whole procedure. In the 6 different sessions that were run, the operational variables were the waste moisture content (25% \u2013 80%) and the amount of energy supplied as MW; residence time 40 min instead was common to all tests. The temperature patterns were recorded, and at the end the whole mass was washed to detach the spores for following cultivation \u2013 count. In this way the critical features of the procedure were identified and ranked by severity. It was foreseen that the procedure would be time-consuming and would require handling of considerable amounts of water and glassware. The experiments showed something more serious: actually, the physiological solution alone \u2013 without any surfactant Agent added \u2013 is unable to detach quantitatively the spores from the waste chips and the beaker walls. Addition of a few drops of surfactants \u2013 as was done by Oliveira et al. (2010) \u2013 is thus a technical detail which is critical for the success of the whole treatment \u2013 analysis chain. Of course we ought to have the certainty that the surfactant chosen does not interfere with the growing medium and / or the bacterial viability in the plate cultivation following. The loss of viable spores in washing the waste batches was calculated by us: 1) sampling and cultivating 1 ml wash solution coming from the control sample inoculated and not irradiated (called K+); and then, 2) comparing the result with the known inoculum. Regrettably, less than 2% spores were found have been recovered. Under the hypothesis that the washing operation is replicable and is not affected by the \u201cirradiated / non irradiated\u201d condition, the disinfection efficiency was then calculated on K+ number. About the results: the MW reduction of microbial load in irradiated batches was just mediocre (98,2%), short of the prescribed 99,99%. The best result was attained with a sample with 60% moisture and unit power input 272 W, corresponding to a unit input of 350 W kg-1 of sample waste. In principle, MW irradiation will heat up waste mass; and this in turn will contribute to microbial inactivation. Water content has a complex relationship with this phenomenon, since the driest batches interact too weakly, while moistest batches do interact but their moisture use up most of the heat. In this experimental campaign, moisture decreased by around 10-30%; but no reliable correlation is evident
Arijit Kumar Chatterjee - One of the best experts on this subject based on the ideXlab platform.
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a simple fast and cost effective method of synthesis of cupric oxide nanoparticle with promising antibacterial potency unraveling the biological and chemical modes of action
Biochimica et Biophysica Acta, 2015Co-Authors: Ruchira Chakraborty, Raj Kumar Sarkar, Arijit Kumar Chatterjee, U Manju, Asoke P Chattopadhyay, Tarakdas BasuAbstract:Abstract Background Gradual attainment of bacterial resistance to antibiotics led us to develop a robust method of synthesis of stable, colloidal cupric oxide nanoparticle of physiological pH with potential antibacterial action. Methods Cu(II) oxide NP was synthesized by reduction–oxidation of CuCl2, using polyvinyl alcohol as stabilizer. Characteristics and antibacterial activity of the particles were investigated by techniques like UV–Vis spectrophotometry, DLS, AFM, TEM, EDS, FTIR, AAS, agar plating, FACS, gel electrophoresis and XPS. Results The NPs were about 50 nm in size and cubic in shape with two surface plasmon peaks at 266 and 370 nm and had semi-conducting behavior with a band gap of 3.40 and 3.96 eV. About 80% of precursor CuCl2 was converted to NP. The minimum inhibitory and the minimum bactericidal concentrations of CuO-NP were respectively 120 and 160 μg/mL for Escherichia coli and 180 and 195 μg/mL for Staphylococcus aureus in Luria–Bertani medium. In growth media, the NPs got modified by media organics with displacement of the stabilizer PVA molecules. This modified NP (around 240 nm) killed cells by generating ROS, which finally caused membrane lipid per-oxidation and chromosomal DNA degradation in NP-treated cells. Conclusion Reports indicate that we are among the few who had prepared CuO-NP in colloidal form. The antibacterial potency of our particle in growth media was much promising than other reports. Our findings demonstrated that ‘particle-specific’ effect, not ‘ion-specific’ one, was responsible for the NP action. General significance The NP may be used as a Sterilizing Agent in various bioprocesses and as substituent of antibiotics, after thorough toxicological study.
U Manju - One of the best experts on this subject based on the ideXlab platform.
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a simple fast and cost effective method of synthesis of cupric oxide nanoparticle with promising antibacterial potency unraveling the biological and chemical modes of action
Biochimica et Biophysica Acta, 2015Co-Authors: Ruchira Chakraborty, Raj Kumar Sarkar, Arijit Kumar Chatterjee, U Manju, Asoke P Chattopadhyay, Tarakdas BasuAbstract:Abstract Background Gradual attainment of bacterial resistance to antibiotics led us to develop a robust method of synthesis of stable, colloidal cupric oxide nanoparticle of physiological pH with potential antibacterial action. Methods Cu(II) oxide NP was synthesized by reduction–oxidation of CuCl2, using polyvinyl alcohol as stabilizer. Characteristics and antibacterial activity of the particles were investigated by techniques like UV–Vis spectrophotometry, DLS, AFM, TEM, EDS, FTIR, AAS, agar plating, FACS, gel electrophoresis and XPS. Results The NPs were about 50 nm in size and cubic in shape with two surface plasmon peaks at 266 and 370 nm and had semi-conducting behavior with a band gap of 3.40 and 3.96 eV. About 80% of precursor CuCl2 was converted to NP. The minimum inhibitory and the minimum bactericidal concentrations of CuO-NP were respectively 120 and 160 μg/mL for Escherichia coli and 180 and 195 μg/mL for Staphylococcus aureus in Luria–Bertani medium. In growth media, the NPs got modified by media organics with displacement of the stabilizer PVA molecules. This modified NP (around 240 nm) killed cells by generating ROS, which finally caused membrane lipid per-oxidation and chromosomal DNA degradation in NP-treated cells. Conclusion Reports indicate that we are among the few who had prepared CuO-NP in colloidal form. The antibacterial potency of our particle in growth media was much promising than other reports. Our findings demonstrated that ‘particle-specific’ effect, not ‘ion-specific’ one, was responsible for the NP action. General significance The NP may be used as a Sterilizing Agent in various bioprocesses and as substituent of antibiotics, after thorough toxicological study.