RESUMEN
UV light is a tool associated with the denaturation of cellular components, DNA damage, and cell disruption. UV treatment is widely used in the decontamination process; however, predicting a sufficient UV dose by using traditional methods is doubtful. In this study, an in-house UVC apparatus was designed to investigate the process of the inactivation of five indicator bacteria when the initial cell concentrations and irradiation intensities varied. Both linear and nonlinear mathematical models were applied to predict the inactivation kinetics. In comparison with the Weibull and modified Chick-Watson models, the Chick-Watson model provided a good fit of the experimental data for five bacteria, Escherichia coli, Klebsiella pneumoniae, Staphylococcus aureus, Streptococcus faecalis, and Bacillus subtilis. The specific death rate (kd) significantly increased when the irradiation intensity (I) increased from 1.41 W/m2 to 3.02 W/m2 and 4.83 W/m2 (P < 0.05). Statistical analysis revealed no significant difference in the kd values among the groups of tested Gram-positive bacteria, Gram-negative bacteria, and B. subtilis spores, but the kd values differed among groups (P < 0.05). The death rate coefficient (k) varied from species to species. The k values of the tested Gram-positive bacteria were higher than those of the Gram-negative bacteria. The thick peptidoglycan layer in the Gram-positive membrane was responsible for UVC resistance. The high guanine-cytosine (GC) content in bacteria also contributed to UV resistance due to the less photoreactive sites on the nucleotides. This investigation provides a good understanding of bacterial inactivation induced by UVC treatment. IMPORTANCE Prevention and control measures for microbial pathogens have attracted worldwide attention due to the recent coronavirus disease 2019 pandemic. UV treatments are used as a commercial control to prevent microbial contamination in diverse applications. Microorganisms exhibit different UV sensitivities, which are often measured by the UV doses required for decreasing the number of microbial contaminants in the logarithmic order. The maximum efficacy of UV is usually observed at 254 nm (residing in the UVC range of the light spectrum). UV technology is a nonthermal physical decontamination measure that does not require any chemicals and consumes low levels of energy while leaving insignificant amounts of chemical residues or toxic compounds. Therefore, obtaining the microbial death kinetics and their intrinsic parameters provided in this study together with the UV photoreaction rate enables advancement in the design of UV treatment systems.
Asunto(s)
COVID-19 , Descontaminación , Bacterias/efectos de la radiación , Desinfección/métodos , Bacterias Gramnegativas/efectos de la radiación , Bacterias Grampositivas/efectos de la radiación , Humanos , Modelos Teóricos , Rayos UltravioletaRESUMEN
The elimination of bacterial pathogens from water using ultraviolet C light-emitting diodes (UVC-LEDs) is a critical technology in terms of hygiene and sanitation. This technology has several advantages, such as low energy consumption, no heating requirements, and high effectiveness. Although several studies have reported the bactericidal effect of UVC-LEDs, little information is available on their bactericidal effect on water reservoirs contaminated with microorganisms. Therefore, the aim of this study was to optimize the bactericidal effects of UVC-LED irradiation, particularly at a wavelength of 278 nm, against major foodborne gram-positive and gram-negative pathogenic bacteria, such as Escherichia coli, Staphylococcus aureus, Bacillus cereus, Salmonella Typhimurium, and Listeria monocytogenes. The efficiency of the bactericidal effect of UVC-LED irradiation was determined based on three variables: exposure time (A, 0-60 min), stirring speed (B, 0-100 rpm), and volume of water (C, 400-1200 mL). To optimize the conditions, the operation of the designed model and results analysis were carried out using Box-Behnken design (BBD) and response surface method (RSM). The final conditions optimized for an effective bactericidal activity included a 60 min exposure time, a 100 rpm stirring speed, and 400 mL of liquid volume. Furthermore, the validation of the optimized model using the predicted values was calculated by the program, which was conducted by matching the actual values within standard deviations. The present study revealed that the optimization of a UVC-LED irradiation model is a promising approach for effectively controlling the contamination of water reservoirs by bacterial pathogens.
Asunto(s)
Bacterias Gramnegativas/efectos de la radiación , Bacterias Grampositivas/efectos de la radiación , Rayos Ultravioleta , Pruebas de Sensibilidad Microbiana , Viabilidad Microbiana/efectos de la radiación , Microbiología del AguaRESUMEN
Silver nanoparticles are well-known for their antimicrobial effect. However, they are potentially toxic in high doses. We explored the possibility of enhancing the bactericidal effect of low concentrations of silver nanoparticles with blue light femtosecond laser irradiation, since such concentrations are less toxic. The growth dynamics of Pseudomonas aeruginosa, Listeria monocytogenes and methicillin-resistant Staphylococcus aureus grown in pre-synthesized silver nanoparticles were measured with or without pre-irradiation with 50 mW and 400 nm femtosecond laser irradiation. With each bacterium, combined treatment with laser and silver nanoparticles significantly reduced bacterial growth, indicating that this form of treatment could be beneficial in the ongoing efforts to reduce the deleterious effects of antibiotic resistant Gram-positive and Gram-negative bacteria. The combined treatment was more antimicrobial than treatment with silver nanoparticles alone or photo-irradiation alone. P. aeruginosa and L. monocytogenes were more susceptible to the bactericidal effects of silver nanoparticles, and the combination of laser treatment and silver nanoparticles than MRSA.
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Bacterias Gramnegativas/efectos de los fármacos , Bacterias Grampositivas/efectos de los fármacos , Rayos Láser , Nanopartículas del Metal/toxicidad , Plata/química , Bacterias Gramnegativas/efectos de la radiación , Bacterias Grampositivas/efectos de la radiación , Nanopartículas del Metal/química , Staphylococcus aureus Resistente a Meticilina/efectos de los fármacos , Staphylococcus aureus Resistente a Meticilina/efectos de la radiación , Pruebas de Sensibilidad Microbiana , Pseudomonas aeruginosa/efectos de los fármacos , Pseudomonas aeruginosa/efectos de la radiación , Factores de TiempoRESUMEN
BACKGROUND: The current approach to reducing bacterial contamination in blood transfusion products is through detection or pathogen reduction methods, some of which utilize ultraviolet (UV) light photosensitizers. A small number of photosensitizers are being used as single agents in combination with UV light, but their efficacy can be limited against some pathogens. Benzophenone (BP) and vitamins B1, B6, and K3 have been identified as effective UVA photosensitizers for inactivation of bacteria. We evaluated whether combining pairs of photosensitizers in this group would have synergistic bactericidal effects on Gram-negative and Gram-positive bacteria. STUDY DESIGN AND METHODS: Bacteria species of Escherichia coli, Bacillus cereus, Staphylococcus aureus, and Klebsiella pneumoniae were mixed with 0 to 100 mM concentrations of photosensitizers and exposed to UVA irradiation at 18 J/cm2 to assess their bactericidal effects. RESULTS: Single photosensitizers irradiated with UVA produced a range of bactericidal activity. When combined in pairs, all demonstrated some synergistic bactericidal effects with up to 4-log reduction above the sum of activities of individual molecules in the pair against bacteria in plasma. Photosensitizer pairs with BP had the highest synergism across all bacteria. With vitamin K3 in the pair, synergism was evident for Gram-positive but not for Gram-negative bacteria. Vitamin B1 and vitamin B6 had the least synergism. These results indicate that a combination approach with multiple photosensitizers may extend effectiveness of pathogen reduction in plasma. CONCLUSIONS: Combining photosensitizers in pathogen reduction methods could improve bactericidal efficacy and lead to use of lower concentrations of photosensitizers to reduce toxicities and unwanted side effects.
Asunto(s)
Antibacterianos/efectos de la radiación , Benzofenonas/efectos de la radiación , Bacterias Gramnegativas/efectos de los fármacos , Bacterias Grampositivas/efectos de los fármacos , Fármacos Fotosensibilizantes/efectos de la radiación , Tiamina/efectos de la radiación , Rayos Ultravioleta , Vitamina B 6/efectos de la radiación , Vitamina K 3/efectos de la radiación , Absorción de Radiación , Antibacterianos/farmacología , Benzofenonas/química , Benzofenonas/farmacología , Sinergismo Farmacológico , Bacterias Gramnegativas/efectos de la radiación , Bacterias Grampositivas/efectos de la radiación , Humanos , Estructura Molecular , Fotoquímica , Fármacos Fotosensibilizantes/farmacología , Tiamina/química , Tiamina/farmacología , Vitamina B 6/química , Vitamina B 6/farmacología , Vitamina K 3/química , Vitamina K 3/farmacologíaRESUMEN
Resistance of microorganisms to antibiotics has led to research on various therapeutic strategies with different mechanisms of action, including photodynamic inactivation (PDI). In this work, we evaluated a cationic, neutral, and anionic meso-tetraphenylporphyrin derivative's ability to inactivate the Gram-negative and Gram-positive bacteria in a planktonic suspension under blue light irradiation. The spectroscopic, physicochemical, redox properties, as well as reactive oxygen species (ROS) generation capacity by a set of photosensitizers varying in lipophilicity were investigated. The theoretical calculations were performed to explain the distribution of the molecular charges in the evaluated compounds. Moreover, logP partition coefficients, cellular uptake, and phototoxicity of the photosensitizers towards bacteria were determined. The role of a specific microbial efflux pump inhibitor, verapamil hydrochloride, in PDI was also studied. The results showed that E. coli exhibited higher resistance to PDI than S. aureus (3-5 logs) with low light doses (1-10 J/cm2). In turn, the prolongation of irradiation (up to 100 J/cm2) remarkably improved the inactivation of pathogens (up to 7 logs) and revealed the importance of photosensitizer photostability. The PDI potentiation occurs after the addition of KI (more than 3 logs extra killing). Verapamil increased the uptake of photosensitizers (especially in E. coli) due to efflux pump inhibition. This effect suggests that PDI is mediated by ROS, the electrostatic charge interaction, and the efflux of photosensitizers (PSs) regulated by multidrug-resistance (MDR) systems. Thus, MDR inhibition combined with PDI gives opportunities to treat more resistant bacteria.
Asunto(s)
Bacterias/efectos de los fármacos , Fármacos Fotosensibilizantes/farmacología , Porfirinas/farmacología , Especies Reactivas de Oxígeno/metabolismo , Bacterias/metabolismo , Bacterias/efectos de la radiación , Farmacorresistencia Bacteriana/efectos de los fármacos , Escherichia coli/efectos de los fármacos , Escherichia coli/metabolismo , Escherichia coli/efectos de la radiación , Bacterias Gramnegativas/efectos de los fármacos , Bacterias Gramnegativas/metabolismo , Bacterias Gramnegativas/efectos de la radiación , Bacterias Grampositivas/efectos de los fármacos , Bacterias Grampositivas/metabolismo , Bacterias Grampositivas/efectos de la radiación , Interacciones Hidrofóbicas e Hidrofílicas , Luz , Microscopía Electrónica de Rastreo , Estructura Molecular , Fotoquimioterapia/métodos , Fármacos Fotosensibilizantes/química , Porfirinas/química , Especificidad de la Especie , Staphylococcus aureus/efectos de los fármacos , Staphylococcus aureus/metabolismo , Staphylococcus aureus/efectos de la radiaciónRESUMEN
Antibiotic resistance is a major public health problem worldwide and the finding of alternative methods for eliminating bacteria is one of the prerogatives of medical research. The indiscriminate use of antibiotics in dentistry, especially for the treatment of peri-implantitis, could lead to superinfections. Alternative methods, like photodynamic therapy mediated by the use of aminolevulinic acid and a red light has been largely described, especially in dentistry, but results were encouraging against Gram-positive bacteria, but limited against Gram-negative. The effectiveness of photodynamic therapy mediated by a novel product containing aminolevulinic acid, Aladent (ALAD) has been tested in this in vitro study, against different types of bacteria particularly involved in the infections of the oral cavity and peri-implantitis. The novelty of ALAD is the marked hydrophilicity that should increase the passage of the molecule through the membrane pores of Gram-negative bacteria. Considering the novelty of the product a preliminary experiment permitted to test the effectiveness against Enterococcus faecalis after 1â¯h of ALAD incubation at different concentrations, with or without different timings of LED irradiation. The count of CFUs and the live/dead observation with fluorescent microscopy showed a significant reduction and killing of bacterium. Then, in the second stage, that could meet the necessity of effectiveness and the clinician's requests to reduce the timing of treatment, ALAD, with and without irradiation, was tested on Staphylococcus aureus, Enterococcus faecalis, Escherichia coli, Veillonella parvula and Porphyromonas gingivalis. In particular, the efficiency of different concentrations of the product after a 25â¯min incubation was tested with and without the adjunctive LED irradiation for 5â¯min. A slight ALAD bactericidal effect was reported for all bacteria, also without LED irradiation, however, the most effective treatment was 25â¯min of 50% ALAD incubation followed by 5â¯min of a red LED. The in vitro tests demonstrated that ALAD gel with LED irradiation exerts a potent antibacterial activity on different bacteria, both Gram-positive and Gram-negative.
Asunto(s)
Ácido Aminolevulínico/farmacología , Bacterias Gramnegativas/efectos de los fármacos , Bacterias Gramnegativas/efectos de la radiación , Bacterias Grampositivas/efectos de los fármacos , Bacterias Grampositivas/efectos de la radiación , Luz , Fármacos Fotosensibilizantes/farmacología , Infecciones Bacterianas/tratamiento farmacológico , Geles , Periimplantitis/tratamiento farmacológico , FotoquimioterapiaRESUMEN
Bacterial infections remain a leading threat to global health because of the misuse of antibiotics and the rise in drug-resistant pathogens. Although several strategies such as photothermal therapy and magneto-thermal therapy can suppress bacterial infections, excessive heat often damages host cells and lengthens the healing time. Here, a localized thermal managing strategy, thermal-disrupting interface induced mitigation (TRIM), is reported, to minimize intercellular cohesion loss for accurate antibacterial therapy. The TRIM dressing film is composed of alternative microscale arrangement of heat-responsive hydrogel regions and mechanical support regions, which enables the surface microtopography to have a significant effect on disrupting bacterial colonization upon infrared irradiation. The regulation of the interfacial contact to the attached skin confines the produced heat and minimizes the risk of skin damage during thermoablation. Quantitative mechanobiology studies demonstrate the TRIM dressing film with a critical dimension for surface features plays a critical role in maintaining intercellular cohesion of the epidermis during photothermal therapy. Finally, endowing wound dressing with the TRIM effect via in vivo studies in S. aureus infected mice demonstrates a promising strategy for mitigating the side effects of photothermal therapy against a wide spectrum of bacterial infections, promoting future biointerface design for antibacterial therapy.
Asunto(s)
Antibacterianos/química , Fototerapia , Infecciones Estafilocócicas/terapia , Resinas Acrílicas/química , Animales , Antibacterianos/farmacología , Antibacterianos/uso terapéutico , Vendajes , Oro/química , Bacterias Gramnegativas/efectos de los fármacos , Bacterias Gramnegativas/efectos de la radiación , Bacterias Grampositivas/efectos de los fármacos , Bacterias Grampositivas/efectos de la radiación , Hidrogeles/química , Rayos Infrarrojos/uso terapéutico , Nanopartículas del Metal/química , Ratones , Infecciones Estafilocócicas/patología , Infecciones Estafilocócicas/veterinariaRESUMEN
Infectious diseases constitute a serious problem for human health and life. Although many bacterial and fungal infections can be successfully cured by commonly used antibiotics, a new threat emerges in the form of microbial resistance. For this reason, researchers try to find not only new active pharmaceutical ingredients for conventional antibiotherapy but also try to develop new strategies of microbial inactivation. Photodynamic antimicrobial chemotherapy, which relies on reactive oxygen species generated in situ in the presence of a photosensitizer and with the light of an appropriate wavelength, is one of them. Porphyrazines have been considered as potential photosensitizers for anticancer and antimicrobial photodynamic therapy. In this study, three tribenzoporphyrazines with dendrimeric peripheral substituents were subjected to in vitro antimicrobial photocytotoxicity study. One magnesium(II) tribenzoporphyrazine with peripheral 3,5-bis(3,5-dimethoxybenzyloxy)benzylsulfanyl substituents was synthesized and subjected to physicochemical characterization using NMR, UV-Vis, and mass spectrometry techniques. In photochemical studies this molecule revealed moderate singlet oxygen generation ability (ΦΔDMF = 0.12, ΦΔDMSO = 0.13). The other two magnesium(II) tribenzoporphyrazines applied in the biological study were 4-[3,5-di(hydroxymethyl)phenoxy]butylsulfanyl-substituted tribenzoporphyrazine and 4-[3,5-bis(benzyloxy)benzyloxy]phenyl-substituted tribenzopyrazinoporphyrazine. For the assessment, three microbial strains were chosen: Gram-positive bacteria Staphylococcus aureus ATCC 25923, Gram-negative bacteria Escherichia coli ATCC 25922, and fungal strain Candida albicans ATCC 10231. Very high activity against Staphylococcus aureus at low 10-6 M concentration was recorded for magnesium(II) tribenzoporphyrazines with peripheral 3,5-bis(3,5-dimethoxybenzyloxy)benzylsulfanyl and 4-[3,5-di(hydroxymethyl)phenoxy]butylsulfanyl substituents with calculated log reductions of 4.4 and 4.8, respectively. It is worth noting that magnesium(II) tribenzoporphyrazine with 4-[3,5-di(hydroxymethyl)phenoxy]butylsulfanyl substituents revealed also 3.2 log reduction in bacterial growth at the concentration 10-7 M.
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Antiinfecciosos/farmacología , Dendrímeros/química , Pirazinas/química , Staphylococcus aureus/efectos de los fármacos , Antiinfecciosos/síntesis química , Antiinfecciosos/química , Candida albicans/efectos de los fármacos , Candida albicans/efectos de la radiación , Bacterias Gramnegativas/efectos de los fármacos , Bacterias Gramnegativas/efectos de la radiación , Bacterias Grampositivas/efectos de los fármacos , Bacterias Grampositivas/efectos de la radiación , Luz , Pruebas de Sensibilidad Microbiana , Pirazinas/síntesis química , Pirazinas/farmacología , Oxígeno Singlete/metabolismo , Staphylococcus aureus/efectos de la radiaciónRESUMEN
Bacterial infection and the issue of antibiotic resistance have become one of the major public health problems worldwide. Thus, searching for new antibacterial agents is urgently required. Hydrogen peroxide, H2O2, as a traditional bactericide, is applied widely for medical treatments. However, the relatively high concentration of H2O2 used in a clinical setting usually inhibits wound healing and even damages normal tissues during disinfection. Here, we synthesized N-doped sponge-like carbon spheres (N-SCSs), which showed excellent mimicking activities for multiple enzymes, including peroxidase, oxidase, superoxide dismutase, and catalase. We then utilized the peroxidase-like activity of the N-SCSs to convert low-concentration H2O2 into radical oxygen species to resist bacteria. The data showed that the antibacterial performance of H2O2 against Gram-negative bacteria (Escherichia coli), Gram-positive bacteria (Staphylococcus aureus), and multidrug-resistant bacteria was improved through the peroxidase-like catalytic reaction of N-SCSs. Importantly, besides generating heat against bacteria, near-infrared laser exposure also promoted the peroxidase activity of N-SCSs, to further generate radical oxygen species to kill bacteria. In addition, this catalytic-photothermal antibacterial strategy demonstrated accelerated recovery of infected wounds in an animal model. Thus, our work provides a new synergetic anti-infection strategy, and further expands the application of carbon-based nanozymes in biomedicine.
Asunto(s)
Antibacterianos/química , Antibacterianos/farmacología , Carbono/química , Luz , Catálisis , Escherichia coli/efectos de los fármacos , Escherichia coli/efectos de la radiación , Bacterias Gramnegativas/efectos de los fármacos , Bacterias Gramnegativas/efectos de la radiación , Peróxido de Hidrógeno/farmacología , Staphylococcus aureus/efectos de los fármacos , Staphylococcus aureus/efectos de la radiaciónRESUMEN
BACKGROUND AND OBJECTIVES: Hospital-acquired infections (HAIs) and multidrug resistant bacteria pose a significant threat to the U.S. healthcare system. With a dearth of new antibiotic approvals, novel antimicrobial strategies are required to help solve this problem. Violet-blue visible light (400-470 nm) has been shown to elicit strong antimicrobial effects toward many pathogens, including representatives of the ESKAPE bacterial pathogens, which have a high propensity to cause HAIs. However, phototherapeutic solutions to prevention or treating infections are currently limited by efficient and nonobtrusive light-delivery mechanisms. STUDY DESIGN/MATERIALS AND METHODS: Here, we investigate the in vitro antimicrobial properties of flexible Corning® light-diffusing fiber (LDF) toward members of the ESKAPE pathogens in a variety of growth states and in the context of biological materials. Bacteria were grown on agar surfaces, in liquid culture and on abiotic surfaces. We also explored the effects of 405 nm light within the presence of lung surfactant, human serum, and on eukaryotic cells. Pathogens tested include Enterococcus spp, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, Enterobacter spp., Staphylococcus epidermidis, Streptococcus pyogenes, Candida albicans, and Escherichia coli. RESULTS: Overall, the LDF delivery of 405 nm violet-blue light exerted a significant degree of microbicidal activity against a wide range of pathogens under diverse experimental conditions. CONCLUSIONS: The results exemplify the fiber's promise as a non-traditional approach for the prevention and/or therapeutic intervention of HAIs. Lasers Surg. Med. © 2019 The Authors. Lasers in Surgery and Medicine Published by Wiley Periodicals, Inc.
Asunto(s)
Candida albicans/efectos de la radiación , Infección Hospitalaria/prevención & control , Desinfección/métodos , Bacterias Gramnegativas/efectos de la radiación , Bacterias Grampositivas/efectos de la radiación , Láseres de Semiconductores/uso terapéutico , Fibras Ópticas , Candidiasis/prevención & control , Desinfección/instrumentación , Infecciones por Bacterias Gramnegativas/prevención & control , Infecciones por Bacterias Grampositivas/prevención & control , Humanos , Terapia por Luz de Baja Intensidad , Pruebas de Sensibilidad MicrobianaRESUMEN
Background and Objectives: The aim of this study was to compare the effects of low-level laser therapy and continuous microwave diathermy on the growth of Gram-negative and Gram-positive bacteria and to establish their efficacy as an alternative therapeutic modality. MATERIALS AND METHODS: Laser fluence of 13 Joules (J)/cm2, 18 J/cm2 and 30 J/cm2 were used against several bacterial strains. Microwave dosages of 25, 50 and 100 watts (W) were used, respectively. RESULTS: A significant difference between the three groups was observed using repeated analysis of variance (RANOVA) (F value: 0.74, and p value: 0.001). The Greenhouse-Geisser correction (GG) revealed significant results for laser irradiation alone. However, effect size calculation showed effects with microwave diathermy as well as laser fluence. CONCLUSIONS: Low-level laser therapy appears to be an effective modality of treatment when compared with continuous microwave diathermy on the Gram-negative and the Gram-positive bacterial strains tested. Microwave diathermy revealed large and medium effects on the bacterial cell counts with dominant effects on Gram-negative strains.
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Antiinfecciosos/normas , Bacterias Gramnegativas/efectos de la radiación , Bacterias Grampositivas/efectos de la radiación , Terapia por Luz de Baja Intensidad/normas , Análisis de Varianza , Antiinfecciosos/efectos de la radiación , Antiinfecciosos/uso terapéutico , Diatermia/métodos , Diatermia/normas , Humanos , Terapia por Luz de Baja Intensidad/métodosRESUMEN
Solar photocatalytic inactivation of Gram-negative bacteria with immobilized TiO2-P25 in a fixed-bed reactor was modeled with simplified kinetic equations. The kinetic parameters are the following: the photocatalytic inactivation coefficient (kd,QUV), the initial bacterial reduction rate (A) in the contact with the disinfecting agent, and the threshold level of damage (n) were determined to report the effect of QUV/TiO2-P25 on bacterial cultivability and viability and to compare the response of bacterial strains to photocatalytic treatment. In addition, the integration of the reactivation coefficient (Cr) in the photocatalytic inactivation equation allowed evaluating the ability of bacterial reactivation after photocatalytic stress. Results showed different responses of the bacteria strains to photocatalytic stress and the ability of certain bacterial strains such as Escherichia coli ATCC25922 and Pseudomonas aeruginosa ATCC4114 to resuscitate after photocatalytic treatment.
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Desinfectantes/farmacología , Desinfección/métodos , Bacterias Gramnegativas/efectos de los fármacos , Luz Solar , Titanio/farmacología , Catálisis , Escherichia coli/efectos de los fármacos , Escherichia coli/efectos de la radiación , Bacterias Gramnegativas/efectos de la radiación , Cinética , Fotoquímica , Titanio/químicaRESUMEN
Silver nanoparticles (AgNPs) have been synthesized by various ways but the green technology methods using food waste materials has been accepted now a days for their cost effectiveness, environmental friendly and effective biomedical application. In the present study an attempt has been made to synthesize AgNPs by using the outer accrescent fruiting calyx of Physalis peruviana fruits, a food waste material under different light source condition, and to investigate their cytotoxic activity against the HepG2 cells as well as their antibacterial and radical scavenging potential. The surface morphology and elemental composition of the biosynthesized AgNPs were evaluated by scanning electron microscopy, energy-dispersive X-ray analysis, and X-ray powder diffraction analysis. Fourier transform infrared spectroscopy of the sample extract and AgNPs was performed to determine the involvement of functional groups in the synthesis, capping, and stabilization process. The AgNPs showed promising cytotoxic activity against the HepG2 cells in a dose-dependent manner. The biosynthesized AgNPs also exhibited moderate antibacterial activity (8.14-10.22â¯mm inhibition zones) against two Gram-negative pathogenic bacteria with promising radical scavenging potential. Overall, the results highlight the effectiveness of the AgNPs for use in antibacterial wound dressing materials and other biomedical applications for the treatment of critical diseases such as cancer.
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Depuradores de Radicales Libres/química , Nanopartículas del Metal/química , Physalis/química , Plata/química , Supervivencia Celular/efectos de los fármacos , Supervivencia Celular/efectos de la radiación , Frutas/química , Frutas/metabolismo , Bacterias Gramnegativas/efectos de los fármacos , Bacterias Gramnegativas/efectos de la radiación , Tecnología Química Verde , Células Hep G2 , Humanos , Luz , Nanopartículas del Metal/toxicidad , Microscopía Electrónica de Rastreo , Physalis/metabolismo , Extractos Vegetales/química , Espectrometría por Rayos X , Espectroscopía Infrarroja por Transformada de Fourier , Difracción de Rayos XRESUMEN
OBJECTIVES: This study investigated the presence of Streptococci, Staphylococci, aerobic gram negative bacteria (AGNB), Candida and bacterial endotoxins in the oral cavities of patients receiving chemo- and/or radiotherapy for cancer. METHODS: Samples of oral cavity rinse were collected from 100 patients on cancer treatment and 70 healthy individuals. Demographic and clinical data were recorded. Samples were cultured onto various agar plates for qualitative and quantitative analysis and tested for the presence of endotoxin. Results were analysed using the Mann-Whitney and chi-square tests. RESULTS: In cancer patients, S. aureus counts were high and 66.7% of patients on chemo- and radiotherapy carried these bacteria (p=<0.05). The Candida carrier rate was significantly (pâ¯<â¯0.01) high in cancer patients (54%). No significant difference was found in the carrier rate of Streptococci and AGNB between the healthy and cancer group as well as between the cancer patients with chemo and radio- and chemotherapy alone. No significant difference was found in the level of endotoxin between the cancer patients and healthy individuals, and cancer patients with and without AGNB. CONCLUSIONS: No differences in the prevalence of bacteria and bacterial endotoxins were found between the cancer patients and healthy individuals. Oral cavity endotoxins did not correlate with the carriage of AGNB. However, due to the high prevalence in cancer patients, the role of Candida species and S. aureus in the pathology may not be excluded.
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Bacterias/clasificación , Bacterias/metabolismo , Endotoxinas/análisis , Boca/microbiología , Neoplasias/complicaciones , Bacterias/efectos de los fármacos , Bacterias/efectos de la radiación , Candida/clasificación , Candida/efectos de los fármacos , Candida/metabolismo , Candida/efectos de la radiación , Quimioterapia , Femenino , Bacterias Gramnegativas/clasificación , Bacterias Gramnegativas/efectos de los fármacos , Bacterias Gramnegativas/metabolismo , Bacterias Gramnegativas/efectos de la radiación , Humanos , Masculino , Persona de Mediana Edad , Mucositis/etiología , Mucositis/microbiología , Neoplasias/radioterapia , Neoplasias/terapia , Radioterapia , Staphylococcus/clasificación , Staphylococcus/efectos de los fármacos , Staphylococcus/metabolismo , Staphylococcus/efectos de la radiación , Staphylococcus aureus , Streptococcus/clasificación , Streptococcus/efectos de los fármacos , Streptococcus/metabolismo , Streptococcus/efectos de la radiaciónRESUMEN
Cerium (IV) oxide (CeO2) is the most accessible noble rare earth metal oxide for the excitation of the excitons by light-harvesting performance. The present work is focused on Erbium doped ceria nanoparticles that were beneficially obtained by hydrothermal method from cerium nitrate and Erbium nitrate as precursors for decomposition of Rhodamine-B (RhB) dye in the polluted waste water removed from the industries. Dye removal efficiency of the catalyst was found to be nearly ~94%. The structural phases, functional groups and the transitions are identified with the help of various techniques. XRD pattern determines the development of cubic phase with the particle size is 20â¯nm. Highly crystalline nature of as-synthesized nanomaterials with an average diameter of 35â¯nm was investigated by HRSEM. The crystalline size, shape and textural morphology, of the Erbium doped ceria nanostructures were analysed by HRTEM. Our results suggest, that the concentration of OH- ion determines the lattice constants and oxygen vacancy in the nanostructures which stimulate the probability of photocatalytic decomposition effect of organic pollutants, due to synergistic approach. In this context, both unhydrolyzed things and their swiftly drip from deceased or scratched cells with conceded membranes, even when the cells embrace some are outstanding attention. Although, the loss of viable cells also depends on epithelial cell dynamically conceal of numerous molar matrix.
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Antibacterianos/química , Cerio/química , Erbio/química , Luz , Nanoestructuras/química , Células A549 , Antibacterianos/farmacología , Catálisis , Membrana Celular/efectos de los fármacos , Membrana Celular/efectos de la radiación , Bacterias Gramnegativas/efectos de los fármacos , Bacterias Gramnegativas/efectos de la radiación , Bacterias Grampositivas/efectos de los fármacos , Bacterias Grampositivas/efectos de la radiación , Humanos , Microscopía Electrónica de Rastreo , Microscopía Electrónica de Transmisión , Nanoestructuras/toxicidad , Tamaño de la Partícula , Rodaminas/química , Espectroscopía Infrarroja por Transformada de Fourier , Difracción de Rayos XRESUMEN
The object of this study was to elucidate the bactericidal mechanism of a 222â¯nm Krypton Chlorine (KrCl) excilamp compared with that of a 254â¯nm Low Pressure mercury (LP Hg) lamp. The KrCl excilamp had higher bactericidal capacity against Gram-positive pathogenic bacteria (Staphylococcus aureus and L. monocytogenes) and Gram-negative pathogenic bacteria (S. Typhimurium and E. coli O157:H7) than did the LP Hg lamp when cell suspensions in PBS were irradiated with each type of UV lamp. It was found out that the KrCl excilamp induced cell membrane damage as a form of depolarization. From the study of respiratory chain dehydrogenase activity and the lipid peroxidation assay, it was revealed that cell membrane damage was attributed to inactivation of enzymes related to generation of membrane potential and occurrence of lipid peroxidation. Direct absorption of UV radiation which led to photoreaction through formation of an excited state was one of the causes inducing cell damage. Additionally, generation of ROS and thus occurrence of secondary damage can be another cause. The LP Hg lamp only induced damage to DNA but not to other components such as lipids or proteins. This difference was derived from differences of UV radiation absorption by cellular materials.
Asunto(s)
Cloruros/química , Manipulación de Alimentos/instrumentación , Irradiación de Alimentos/instrumentación , Microbiología de Alimentos/instrumentación , Enfermedades Transmitidas por los Alimentos/prevención & control , Bacterias Gramnegativas/efectos de la radiación , Bacterias Grampositivas/efectos de la radiación , Criptón/química , Compuestos de Mercurio/química , Rayos Ultravioleta , Daño del ADN , Diseño de Equipo , Escherichia coli/crecimiento & desarrollo , Escherichia coli/metabolismo , Escherichia coli/efectos de la radiación , Enfermedades Transmitidas por los Alimentos/microbiología , Bacterias Gramnegativas/crecimiento & desarrollo , Bacterias Gramnegativas/metabolismo , Bacterias Grampositivas/crecimiento & desarrollo , Bacterias Grampositivas/metabolismo , Cinética , Peroxidación de Lípido/efectos de la radiación , Listeria monocytogenes/crecimiento & desarrollo , Listeria monocytogenes/metabolismo , Listeria monocytogenes/efectos de la radiación , Estrés Oxidativo/efectos de la radiación , Especies Reactivas de Oxígeno/metabolismo , Salmonella typhimurium/crecimiento & desarrollo , Salmonella typhimurium/metabolismo , Salmonella typhimurium/efectos de la radiación , Staphylococcus aureus/crecimiento & desarrollo , Staphylococcus aureus/metabolismo , Staphylococcus aureus/efectos de la radiaciónRESUMEN
Lasers are instrumental in advanced bioimaging and Raman spectroscopy. However, they are also well known for their destructive effects on living organisms, leading to concerns about the adverse effects of laser technologies. To implement Raman spectroscopy for cell analysis and manipulation, such as Raman-activated cell sorting, it is crucial to identify nondestructive conditions for living cells. Here, we evaluated quantitatively the effect of 532-nm laser irradiation on bacterial cell fate and growth at the single-cell level. Using a purpose-built microfluidic platform, we were able to quantify the growth characteristics, i.e., specific growth rates and lag times of individual cells, as well as the survival rate of a population in conjunction with Raman spectroscopy. Representative Gram-negative and Gram-positive species show similar trends in response to a laser irradiation dose. Laser irradiation could compromise the physiological function of cells, and the degree of destruction is both dose and strain dependent, ranging from reduced cell growth to a complete loss of cell metabolic activity and finally to physical disintegration. Gram-positive bacterial cells are more susceptible than Gram-negative bacterial strains to irradiation-induced damage. By directly correlating Raman acquisition with single-cell growth characteristics, we provide evidence of nondestructive characteristics of Raman spectroscopy on individual bacterial cells. However, while strong Raman signals can be obtained without causing cell death, the variety of responses from different strains and from individual cells justifies careful evaluation of Raman acquisition conditions if cell viability is critical.IMPORTANCE In Raman spectroscopy, the use of powerful monochromatic light in laser-based systems facilitates the detection of inherently weak signals. This allows environmentally and clinically relevant microorganisms to be measured at the single-cell level. The significance of being able to perform Raman measurement is that, unlike label-based fluorescence techniques, it provides a "fingerprint" that is specific to the identity and state of any (unlabeled) sample. Thus, it has emerged as a powerful method for studying living cells under physiological and environmental conditions. However, the laser's high power also has the potential to kill bacteria, which leads to concerns. The research presented here is a quantitative evaluation that provides a generic platform and methodology to evaluate the effects of laser irradiation on individual bacterial cells. Furthermore, it illustrates this by determining the conditions required to nondestructively measure the spectra of representative bacteria from several different groups.
Asunto(s)
Bacterias Gramnegativas/efectos de la radiación , Bacterias Grampositivas/efectos de la radiación , Rayos Láser , Espectrometría Raman/métodos , Bacterias Gramnegativas/crecimiento & desarrollo , Bacterias Gramnegativas/fisiología , Bacterias Grampositivas/crecimiento & desarrollo , Bacterias Grampositivas/fisiología , MicrofluídicaRESUMEN
The aim of the present study was to examine the effect of gamma radiation on levofloxacin. Powder form of levofloxacin was subjected to different radiation doses (25, 50, 75, 100 and 125kGy) of Cobalt-60 source in a Gammacell-220 at a rate of 8.5 Gray/hr. The effect of radiation has been investigated with the aid of different spectroscopic techniques (UV-Vis, FT-IR), scanning electron microscopy (SEM), X-ray diffraction (XRD), and by antibacterial activities. UV data did not reveal significant changes in the structure of levofloxacin which is supported by scanning electron microscopy. However, X-rays diffraction shows a change in crystallinity of levofloxacin to an amorphous structure and this has been reflected on the morphology of this compound as indicated by SEM images. The antibacterial activities, on the other hand, reveal resistance of irradiated levofloxacin against bacteria, where some bacteria were highly affected by the irradiated drug. Similarly, FT-IR data show some changes in the functional groups principal absorption bands, in the IR spectrum, at frequencies 3286, 2846, 1716 and 1620 cm-1 for the O-H stretching band of quinolone, C-H stretching band, and C=O stretching band of carboxylic and pyridine. In addition, new peaks appeared which were not seen in the non-irradiated spectrum. In conclusion, some changes occurred in levofloxacin drug with the passage of radiation but the drug was chemically stable.
Asunto(s)
Antibacterianos/efectos de la radiación , Rayos gamma , Levofloxacino/efectos de la radiación , Esterilización/métodos , Antibacterianos/química , Bacterias Gramnegativas/efectos de la radiación , Bacterias Grampositivas/efectos de la radiación , Levofloxacino/química , Pruebas de Sensibilidad Microbiana , Estructura Molecular , Polvos , Estereoisomerismo , Propiedades de SuperficieRESUMEN
We synthesised a new type of photochromic tungsten oxide nanoparticles, analysed their photocatalytic activity and carried out a thorough analysis of their effect on prokaryotic and eukaryotic organisms. Ultrasmall hydrated tungsten oxide nanoparticles were prepared by means of hydrothermal treatment of tungstic acid in the presence of polyvinylpyrrolidone as a template, stabiliser and growth regulator. Tungstic acid was synthesised through an ion-exchange method using sodium tungstate solution and a strongly acidic cation exchange resin. Upon illumination, photochromic nanoparticles of WO3 were shown to increase greatly their toxicity against both bacterial (both gram-positive and gram-negative - P. aeruginosa, E. coli and S. aureus) and mammalian cells (primary mouse embryonic fibroblasts); under the same conditions, fungi (C. albicans) were less sensitive to the action of tungsten oxide nanoparticles. UV irradiation of primary mouse fibroblasts in the presence of WO3 nanoparticles demonstrated a time- and dose-dependent toxic effect, the latter leading to a significant decrease in dehydrogenase activity and an increase in the number of dead cells. WO3 nanoparticles were photocatalytically active under both UV light and even diffused daylight filtered through a window glass, leading to indigo carmine organic dye discolouration. The obtained experimental data not only show good prospects for biomedical applications of tungsten trioxide, but also demonstrate the need for clear control of biosafety when it is used in various household materials and appliances.
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Nanopartículas del Metal/química , Óxidos/química , Tungsteno/química , Animales , Catálisis , Línea Celular , Supervivencia Celular/efectos de los fármacos , Supervivencia Celular/efectos de la radiación , Colorantes/química , Hongos/efectos de los fármacos , Hongos/efectos de la radiación , Bacterias Gramnegativas/efectos de los fármacos , Bacterias Gramnegativas/efectos de la radiación , Bacterias Grampositivas/efectos de los fármacos , Bacterias Grampositivas/efectos de la radiación , Nanopartículas del Metal/toxicidad , Ratones , Microscopía Fluorescente , Oxidorreductasas/metabolismo , Rayos UltravioletaRESUMEN
With the increase of antibiotic resistances in microorganisms, photodynamic inactivation (PDI) as a clinically proven antibacterial therapy is gaining increasing attention in recent years due to its high efficacy. Herein, we reported two covalent organic frameworks (COFs) materials, namely COFs-Trif-Benz and COF-SDU1, as effective type-II photosensitizers for photodynamic inactivation of bacteria. COFs-Trif-Benz and COF-SDU1 are synthesized through a facile solvothermal reaction between tri-(4-formacylphenoxy)-1,3,5-triazine (trif) and benzidine or p-phenylenediamine with high yield. Their highly ordered and porous structures were confirmed by Fourier transform infrared (FT-IR) spectra, solid state 13C CP/MAS NMR spectrum, powder X-ray diffraction (PXRD) and Brunauer-Emmett-Teller (BET) analyses. The electronic absorption spectra and electrochemical experiments revealed that the extensive π-conjugation over COFs-Trif-Benz and COF-SDU1 greatly enhance their absorbance capability for visible light and make them have a lower band gap. The photocatalytic antibacterial assay was studied against both Gram-positive Staphylococcus aureus (S. aureus) and Gram-negative Escherichia coli O86:B7 (E. coli O86) bacteria. Two materials can kill more than 90% bacteria at concentrations of 100µgmL-1 after 60-90min of illumination. Thus, both COFs are effective photosensitizers. Mechanism investigation revealed the antibacterial characteristics of the COFs-Trif-Benz and COF-SDU1 can generate reactive oxygen species (ROS) by energy transfer to molecular oxygen (3O2) to produce a highly reactive singlet oxygen (1O2). Hence, the two materials during the photodynamic were mainly via mechanism type II.