RESUMEN
The increasing and alarming panorama of bacterial infections and associated morbidities that occur during medical and hospital procedures makes the development of technologies that aid in controlling such bacterial infections of utmost importance. Recent studies have shown that formulations with metal nanoparticles exhibit good antibacterial properties against a broad spectrum of microorganisms. Moreover, it was demonstrated that some biologically active polymeric materials, when applied in combination with chemical antimicrobial agents, enhance the therapeutic action of the latter. The research effort entertained herein aimed at the physico-chemical characterisation of silver nanoparticles obtained by chemical reduction, stabilised by bioactive polymers polyvinyl alcohol and polyvinylpyrrolidone, and further co-stabilised by pluronic F68. Scanning electron microscopy images of the nanoparticles produced, coated with different stabilisers, have shown that the chemical nature of the stabilisation effect promoted incorporation of pluronic in the nanoparticles and was closely related to an increase in the silver concentration in the nanoparticle samples obtained via energy-dispersive X-ray spectroscopy. The study described herein also shows that the nature of the stabiliser favours the interaction of pluronic F68 with samples containing silver nanoparticles.
Asunto(s)
Nanopartículas del Metal/química , Poloxámero/química , Alcohol Polivinílico/química , Povidona/química , Plata/química , Antibacterianos/farmacología , Escherichia coli/efectos de los fármacos , Pruebas de Sensibilidad Microbiana , Microscopía Electrónica de Rastreo , Microscopía Electrónica de Transmisión , Poloxámero/farmacología , Alcohol Polivinílico/farmacología , Povidona/farmacología , Espectrometría por Rayos X , Espectrofotometría Ultravioleta , Staphylococcus aureus/efectos de los fármacosRESUMEN
The authors report the comparative antibacterial activity of silver nanoparticles synthesised by biological (using Fusarium oxysporum) and chemical routes in the presence and absence of pluronic F68 as a stabilising agent. The production of silver nanoparticles was evidenced by UV-visible spectra, with absorbance at about 420 nm in the case of both biological and chemical synthesis. X-ray diffraction pattern confirmed the presence of face-centred cubic structure (FCC plane). The nanoparticles characterised by transmission and scanning electron microscopy showed spherical silver nanoparticles with size range of 5-40 and 10-70 nm in the case of biologically and chemically synthesised nanoparticles, respectively. Addition of pluronic F68 showed the stabilisation of silver nanoparticles. Antibacterial efficacy of silver nanoparticles demonstrated different inhibitory activity against Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus. Overall, biologically synthesised silver nanoparticles showed higher activity as compared with chemically synthesised nanoparticles. Silver nanoparticles synthesised in the presence of pluronic F68 by the chemical route exhibited synergism in antibacterial activity as compared with those synthesised without pluronic F68. On the contrary, biogenic silver nanoparticles without pluronic F68 showed higher antibacterial potential.
Asunto(s)
Antibacterianos/síntesis química , Fenómenos Fisiológicos Bacterianos/efectos de los fármacos , Excipientes/química , Nanopartículas del Metal/administración & dosificación , Poloxámero/síntesis química , Plata/administración & dosificación , Antibacterianos/administración & dosificación , Supervivencia Celular/efectos de los fármacos , Relación Dosis-Respuesta a Droga , Composición de Medicamentos/métodos , Sinergismo Farmacológico , Nanopartículas del Metal/química , Nanopartículas del Metal/ultraestructura , Tamaño de la Partícula , Plata/químicaRESUMEN
BACKGROUND: Multidrug resistant microorganisms are a growing challenge and new substances that can be useful to treat infections due to these microorganisms are needed. Silver nanoparticle may be a future option for treatment of these infections, however, the methods described in vitro to evaluate the inhibitory effect are controversial. RESULTS: This study evaluated the in vitro activity of silver nanoparticles against 36 susceptible and 54 multidrug resistant Gram-positive and Gram-negative bacteria from clinical sources. The multidrug resistant bacteria were oxacilin-resistant Staphylococcus aureus, vancomycin-resistant Enterococcus spp., carbapenem- and polymyxin B-resistant A. baumannii, carbapenem-resistant P. aeruginosa and carbapenem-resistant Enterobacteriaceae. We analyzed silver nanoparticles stabilized with citrate, chitosan and polyvinyl alcohol and commercial silver nanoparticle. Silver sulfadiazine and silver nitrate were used as control. Different methods were used: agar diffusion, minimum inhibitory concentration, minimum bactericidal concentration and time-kill. The activity of AgNPs using diffusion in solid media and the MIC methods showed similar effect against MDR and antimicrobial-susceptible isolates, with a higher effect against Gram-negative isolates. The better results were achieved with citrate and chitosan silver nanoparticle, both with MIC90 of 6.75 µg mL(-1), which can be due the lower stability of these particles and, consequently, release of Ag(+) ions as revealed by X-ray diffraction (XRD). The bactericidal effect was higher against antimicrobial-susceptible bacteria. CONCLUSION: It seems that agar diffusion method can be used as screening test, minimum inhibitory concentration/minimum bactericidal concentration and time kill showed to be useful methods. The activity of commercial silver nanoparticle and silver controls did not exceed the activity of the citrate and chitosan silver nanoparticles. The in vitro inhibitory effect was stronger against Gram-negative than Gram-positive, and similar against multidrug resistant and susceptible bacteria, with best result achieved using citrate and chitosan silver nanoparticles. The bactericidal effect of silver nanoparticle may, in the future, be translated into important therapeutic and clinical options, especially considering the shortage of new antimicrobials against the emerging antimicrobial resistant microorganisms, in particular against Gram-negative bacteria.
Asunto(s)
Antibacterianos/farmacología , Bacterias/efectos de los fármacos , Infecciones Bacterianas/tratamiento farmacológico , Nanopartículas del Metal/química , Pruebas de Sensibilidad Microbiana/métodos , Plata/farmacología , Antibacterianos/química , Bacterias/citología , Bacterias/crecimiento & desarrollo , Infecciones Bacterianas/microbiología , Farmacorresistencia Bacteriana Múltiple , Humanos , Plata/químicaRESUMEN
Particulate matter from diesel exhaust (DEP) has toxic properties and can activate intracellular signaling pathways and induce metabolic changes. This study was conducted to evaluate the activation of extracellular signal-regulated kinase (ERK) and c-Jun N-terminal kinase (JNK) and to analyze the mucin profile (acid (AB(+) ), neutral (PAS(+) ), or mixed (AB/PAS(+) ) mucus) and vacuolization (V) of tracheal explants after treatment with 50 or 100 µg/mL DEP for 30 or 60 min. Western blot analyses showed small increases in ERK1/2 and JNK phosphorylation after 30 min of 100 µg/mL DEP treatment compared with the control. An increase in JNK phosphorylation was observed after 60 min of treatment with 50 µg/mL DEP compared with the control. We did not observe any change in the level of ERK1/2 phosphorylation after treatment with 50 µg/mL DEP. Other groups of tracheas were subjected to histological sectioning and stained with periodic acid-Schiff (PAS) reagent and Alcian Blue (AB). The stained tissue sections were then subjected to morphometric analysis. The results obtained were compared using ANOVA. Treatment with 50 µg/mL DEP for 30 min or 60 min showed a significant increase (p < 0.001) in the amount of acid mucus, a reduction in neutral mucus, a significant reduction in mixed mucus, and greater vacuolization. Our results suggest that compounds found in DEPs are able to activate acid mucus production and enhance vacuolization and cell signaling pathways, which can lead to airway diseases.
Asunto(s)
Contaminantes Atmosféricos/toxicidad , Sistema de Señalización de MAP Quinasas/efectos de los fármacos , Mucinas/metabolismo , Material Particulado/toxicidad , Tráquea/efectos de los fármacos , Emisiones de Vehículos/toxicidad , Animales , Apoptosis/efectos de los fármacos , Relación Dosis-Respuesta a Droga , Células Epiteliales/efectos de los fármacos , Células Epiteliales/metabolismo , Células Epiteliales/patología , Quinasas MAP Reguladas por Señal Extracelular/metabolismo , Proteínas Quinasas JNK Activadas por Mitógenos/metabolismo , Ratones , Ratones Endogámicos BALB C , Moco/metabolismo , Fosforilación , Transducción de Señal/efectos de los fármacos , Tráquea/metabolismo , Tráquea/patologíaRESUMEN
Advances in technologies to enable water reuse in industry have been the objective of many research efforts, mainly due to the need to reduce the use of natural resources and due to factors related to their availability. This paper evaluates the crystallization of salts from petrochemical saline waste to achieve zero water discharge by the recovery of water and dissolved salts as a solid mixture. In line with process symbiosis, the recovered water should be suitable for use as cooling water in heat exchangers. Vacuum evaporative crystallization, at the batch scale, was used to remove the salts present in the concentrated stream from reverse electrodialysis of pretreated wastewater by a biological process. The partition of organic compounds in the feed solution between the condensate and the mother liquor was obtained from measurements of the total organic carbon and total nitrogen in the solutions. The solid phases formed experimentally are compared with those predicted by chemical modelling by PHREEQC. The recovered water presented almost 50 times less total dissolved solids than the feed stream (from 2100 to 44â mg/L). Calcium sulphate hydrate, calcium sulphate and sodium chloride were the majority crystalline phases formed, in accordance with the modelling by PHREEQC.
Asunto(s)
Conservación de los Recursos Energéticos/métodos , Diálisis/instrumentación , Electroquímica/instrumentación , Sales (Química)/aislamiento & purificación , Purificación del Agua/instrumentación , Agua/química , Diálisis/métodos , Electroquímica/métodos , Diseño de Equipo , Análisis de Falla de Equipo , Sales (Química)/química , Purificación del Agua/métodosRESUMEN
BACKGROUND: Silver nanoparticles (AgNps) have attracted much interest in biomedical engineering, since they have excellent antimicrobial properties. Therefore, AgNps have often been considered for incorporation into medical products for skin pathologies to reduce the risk of contamination. This study aims at evaluating the antimicrobial effectiveness of AgNps stabilized by pluronic™ F68 associated with other polymers such as polyvinyl alcohol (PVA) and polyvinylpyrrolidone (PVP). METHODS: AgNps antimicrobial activity was evaluated using the minimum inhibitory concentration (MIC) method. The action spectrum was evaluated for different polymers associated with pluronic™ F68 against the gram negative bacteria P. aeuroginosa and E. coli and the gram positive bacteria S. Aureus. RESULTS: AgNps stabilized with PVP or PVA and co-stabilized with pluronic™ F68 are effective against E. coli and P. aeruginosa microorganisms, with MIC values as low as 0.78% of the concentration of the original AgNps dispersion. The antimicrobial action against S. aureus is poor, with MIC values not lower than 25%. CONCLUSIONS: AgNps stabilized by different polymeric systems have shown improved antimicrobial activity against gram-negative microorganisms in comparison to unstabilized AgNps. Co-stabilization with the bioactive copolymer pluronic™ F68 has further enhanced the antimicrobial effectiveness against both microorganisms. A poor effectiveness has been found against the gram-positive S. aureus microorganism. Future assays are being delineated targeting possible therapeutic applications.