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1.
Carbohydr Polym ; 217: 15-25, 2019 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-31079671

RESUMO

A bifunctional interfacial layer was introduced onto the surface of cotton fabric which not only enhanced the interfacial bonding between Ag@ZnO and organic substrates but also improved the photocatalytic performance simultaneously. In detail, a modified cotton fabric (denoted as Cot-g-Si/Ag@ZnO) was fabricated through radiation-induced graft polymerization of γ-methacryloxypropyl trimethoxysilane and followed the in-situ formation of ZnO and loading of Ag nanoparticles simultaneously. Owing to ZnOSi between the graft chains and Ag@ZnO photocatalyst, the charge carrier concentration increased and Ag was prevented from oxidizing through the partial separation from ZnO, leading to enhanced near-field amplitudes of the localized surface plasmon resonance. Cot-g-Si/Ag@ZnO also exhibited excellent photocorrosion resistance, photostability and laundering durability. Its photocatalytic activity was fully maintained after several photodegradation cycles; moreover, after laundering durability test, the photocatalytic activity was improved compared with the newly prepared one. Credible mechanism for the photocatalytic activity of Cot-g-Si/Ag@ZnO under sunlight irradiation is proposed.


Assuntos
Antibacterianos/farmacologia , Fibra de Algodão , Nanopartículas Metálicas/química , Siloxanas/farmacologia , Prata/química , Óxido de Zinco/farmacologia , Antibacterianos/química , Antibacterianos/efeitos da radiação , Catálise , Escherichia coli/efeitos dos fármacos , Gossypium/química , Luz , Nanopartículas Metálicas/efeitos da radiação , Azul de Metileno/efeitos da radiação , Fotólise , Rodaminas/efeitos da radiação , Siloxanas/química , Siloxanas/efeitos da radiação , Prata/efeitos da radiação , Staphylococcus aureus/efeitos dos fármacos , Óxido de Zinco/química , Óxido de Zinco/efeitos da radiação
2.
ACS Appl Mater Interfaces ; 11(5): 4858-4866, 2019 Feb 06.
Artigo em Inglês | MEDLINE | ID: mdl-30628779

RESUMO

Molybdenum disulfide (MoS2) nanosheets have received considerable interest due to their superior physicochemical performances to graphene nanosheets. As the lateral size and layer thickness decrease, the formed MoS2 quantum dots (QDs) show more promise as photocatalysts, endowing them with potential antimicrobial properties under environmental conditions. However, studies on the antibacterial photodynamic therapy of MoS2 QDs have rarely been reported. Here, we show that MoS2 QDs more effectively promote the creation and separation of electron-hole pair than MoS2 nanosheets, resulting in the formation of multiple reactive oxygen species (ROS) under simulated solar light irradiation. As a result, photoexcited MoS2 QDs show remarkably enhanced antibacterial activity, and the ROS-mediated oxidative stress plays a dominant role in the antibacterial mechanism. The in vivo experiments showed that MoS2 QDs are efficacious in wound healing under simulated solar light irradiation and exert protective effects on normal tissues, suggesting good biocompatibility properties. Our findings provide a full description of the photochemical behavior of MoS2 QDs and the resulting antibacterial activity, which might advance the development of MoS2-based nanomaterials as photodynamic antibacterial agents under environmental conditions.


Assuntos
Antibacterianos , Dissulfetos , Molibdênio , Pontos Quânticos , Animais , Antibacterianos/química , Antibacterianos/farmacologia , Antibacterianos/efeitos da radiação , Antibacterianos/toxicidade , Bactérias/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Dissulfetos/química , Dissulfetos/farmacologia , Dissulfetos/toxicidade , Células Endoteliais da Veia Umbilical Humana , Humanos , Camundongos , Camundongos Endogâmicos BALB C , Molibdênio/química , Molibdênio/farmacologia , Molibdênio/toxicidade , Estresse Oxidativo/efeitos dos fármacos , Processos Fotoquímicos , Pontos Quânticos/química , Pontos Quânticos/efeitos da radiação , Pontos Quânticos/toxicidade , Espécies Reativas de Oxigênio , Infecção dos Ferimentos
3.
J Photochem Photobiol B ; 191: 52-58, 2019 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-30580185

RESUMO

The bactericidal activity of ferulic acid (FA) against various microorganisms was remarkably enhanced by ultraviolet-A (UV-A) irradiation (wavelength, 365 nm). However, the bactericidal mechanism in the photo-combination system has not been evaluated. In the present study, this combined treatment was characterized by investigating associated changes in cellular functions of Escherichia coli, including assessments of respiratory activity, lipid peroxidation, membrane permeability, and damage to DNA and the cell surface. FA adsorbed onto and was incorporated into bacterial membranes, and the affinity resulted in decreased respiratory activity and enhanced lipid peroxidation in the cytoplasmic membrane with low-fluence (1.0 J/cm2) UV-A irradiation. Flow cytometry analysis revealed that additional exposure (8 J/cm2) combined with FA (1 mg/mL) induced increased cell permeability, yielding a 4.8-log decrease in the viable cell count. Morphologically, the treated cells exhibited a bacterial membrane dysfunction, producing many vesicles on the cell surface. However, despite this effect on the cell surface, plasmid DNA transformed into FA-treated E. coli maintained supercoiled integrity with negligible DNA oxidation. Our data strongly suggested that FA functions inside and outside the bacterial membrane; UV-A exposure in the presence of FA then causes increased oxidative modification and subsequent disruption of the bacterial membrane, without causing detectable genotoxicity.


Assuntos
Antibacterianos/farmacologia , Ácidos Cumáricos/farmacologia , Raios Ultravioleta , Antibacterianos/efeitos da radiação , Permeabilidade da Membrana Celular , Respiração Celular , Ácidos Cumáricos/efeitos da radiação , Dano ao DNA/efeitos dos fármacos , Dano ao DNA/efeitos da radiação , Escherichia coli/citologia , Escherichia coli/efeitos dos fármacos , Escherichia coli/efeitos da radiação , Peroxidação de Lipídeos
4.
Sci Total Environ ; 652: 1051-1061, 2019 Feb 20.
Artigo em Inglês | MEDLINE | ID: mdl-30586792

RESUMO

This research reports for the first time the full-scale application of different homogeneous Advanced Oxidation Processes (AOPs) (H2O2/UV-C, PMS/UV-C and PMS/Fe(II)/UV-C) for the removal of antibiotics (ABs) and antibiotic resistance genes (ARGs) from wastewater effluent at Estiviel wastewater treatment plant (WWTP) (Toledo, Spain). AOPs based on the photolytic decomposition of H2O2 and peroxymonosulfate tested at low dosages (0.05-0.5 mM) and with very low UV-C contact time (4-18 s) demonstrated to be more efficient than UV-C radiation alone on the removal of the analyzed ABs. PMS (0.5 mM) combined with UV-C (7 s contact time) was the most efficient treatment in terms of AB removal: 7 out of 10 ABs detected in the wastewater were removed more efficiently than using the other oxidants. In terms of ARGs removal efficiency, UV-C alone seemed the most efficient treatment, although H2O2/UV-C, PMS/UV-C and PMS/Fe(II)/UV-C were supposed to generate higher concentrations of free radicals. The results show that treatments with the highest removal of ABs and ARGs did not coincide, which could be attributed to the competition between DNA and oxidants in the absorption of UV photons, reducing the direct photolysis of the DNA. Whereas the photolytic ABs removal is improved by the generation of hydroxyl and sulfate radicals, the opposite behavior occurs in the case of ARGs. These results suggest that a compromise between ABs and ARGs removal must be achieved in order to optimize wastewater treatment processes.


Assuntos
Antibacterianos/análise , Oxidantes/química , Raios Ultravioleta , Águas Residuárias/química , Poluentes Químicos da Água/análise , Purificação da Água/métodos , Antibacterianos/efeitos da radiação , Catálise , Peróxido de Hidrogênio/química , Oxirredução , Peróxidos/química , Fotólise , Espanha , Poluentes Químicos da Água/efeitos da radiação
5.
Water Sci Technol ; 2017(2): 527-533, 2018 May.
Artigo em Inglês | MEDLINE | ID: mdl-29851405

RESUMO

In this paper, Fe3O4/graphene (Fe3O4/GE) nanocomposites were prepared by a co-precipitation method and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and UV-vis diffuse reflectance spectra (UV-vis DRS). The composites were used in combination with Fe(VI) to construct a Fe(VI)-Fe3O4/GE system in order to degrade ciprofloxacin (CIP) in simulated water samples. The photocatalytic properties of Fe(VI)-Fe3O4/GE were evaluated under visible light irradiation. The concentration of CIP in solution was detected by high performance liquid chromatography (HPLC). A series of results showed that Fe(VI), as a good electron capture agent, could significantly improve the treatment performance. Major determining factors during CIP degradation were also investigated, in which solution pH of 9, Fe(VI) to Fe3O4/GE dosage ratio of 1:25 and GE content in the Fe3O4/GE nanocomposites of 10 wt% were found to be the best experimental conditions. The results demonstrated that the Fe(VI)-Fe3O4/GE system could offer an alternative process in water treatment in addition to the current Fe(VI)-UV/TiO2 process.


Assuntos
Ciprofloxacino/química , Grafite/análise , Compostos de Ferro/análise , Luz , Eliminação de Resíduos Líquidos/métodos , Poluentes Químicos da Água/química , Antibacterianos/química , Antibacterianos/efeitos da radiação , Ciprofloxacino/efeitos da radiação , Nanocompostos/análise , Poluentes Químicos da Água/efeitos da radiação
6.
Chemosphere ; 208: 606-613, 2018 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-29890499

RESUMO

Gamma radiolytic degradation of an antibiotic, ofloxacin (OFX) was investigated under different experimental conditions. The parameters such as initial OFX concentration, solution pH, absorbed dose and the concentrations of inorganic (CO32-) and organic (t-BuOH) additives were optimized to achieve the efficient degradation of OFX. The degradation dose constant values of OFX were calculated as 2.364, 1.159, 0.776 and 0.618 kGy-1 for the initial OFX concentrations of 0.05, 0.1, 0.15 and 0.2 mM with their corresponding (G (-OFX)) values of 0.481, 0.684, 1.755 and 1.971, respectively. Degradation rate of OFX was significantly increased with increase in the absorbed dose and decrease in the initial OFX concentration under acidic condition when compared to neutral or alkaline condition. Reaction of OFX in the presence of CO32- and t-BuOH showed that the degradation was primarily caused by the reaction of OFX with radiolytically generated reactive hydroxyl radicals. Mineralization extent of OFX was determined in terms of percentage reduction in total organic carbon (TOC) and results revealed that the addition of H2O2 enhanced the mineralization of OFX from 29% to 36.1% with H2O2 dose of 0.5 mM at an absorbed dose of 3.0 kGy. Based on the LC-QTOF-MS analysis, gamma radiolytic degradation intermediates/products of OFX were identified and the possible degradation pathways of OFX were proposed. Cytotoxicity study of the irradiated OFX solutions showed that gamma radiation has potential to detoxify OFX.


Assuntos
Raios gama , Ofloxacino/efeitos da radiação , Poluentes Químicos da Água/efeitos da radiação , Antibacterianos/efeitos da radiação , Cromatografia Líquida , Peróxido de Hidrogênio
7.
Water Res ; 134: 253-260, 2018 05 01.
Artigo em Inglês | MEDLINE | ID: mdl-29428778

RESUMO

Lately, special attention has been given to veterinary cephalosporin antibiotics due to their broad activity spectrum and significant consumption. Indeed, the determination of hydrolytic and photolytic kinetics provides a better comprehension of the undesired persistence of cephalosporins in aqueous matrices. In this work, the two widely used veterinary antibiotics ceftiofur (CEF) and cefapirin (CEPA) showed high instability under alkaline conditions, degrading in few minutes at pH > 11. In buffered solutions at neutral pH and natural temperature (T = 22 ±â€¯1 °C), both drugs presented moderate stability (t½â€¯= 3 d, CEPA and 1.4 d, CEF). Our study also demonstrated that CEPA and CEF speciation did not significantly influence the direct photolysis rates. Using a simulated water disinfection set-up (λ = 254 nm), all ionic species of CEF and CEPA presented fast and similar pseudo-first order degradation rates, kapp 0.0095 ±â€¯0.0004 and 0.0092 ±â€¯0.001 cm2 mJ-1, respectively. Furthermore, using surface water in hydrolysis experiments, CEF demonstrated significant matrix-dependent stability with a half-life (t½â€¯= 14.7 d) tenfold higher than in buffered solutions. In contrast, CEPA presented a very similar hydrolysis rate in river water (t½â€¯= 4.2 d) and a subtle faster photo-degradation rate in this same matrix (kapp 0.0128 ±â€¯0.001 cm2 mJ-1), highlighting the importance of disinfection radiation for cephalosporin depletion in aqueous environments.


Assuntos
Antibacterianos , Cefalosporinas , Cefapirina , Poluentes Químicos da Água , Antibacterianos/química , Antibacterianos/efeitos da radiação , Catálise , Cefalosporinas/química , Cefalosporinas/efeitos da radiação , Cefapirina/química , Cefapirina/efeitos da radiação , Concentração de Íons de Hidrogênio , Hidrólise , Cinética , Fotólise , Rios , Temperatura Ambiente , Poluentes Químicos da Água/química , Poluentes Químicos da Água/efeitos da radiação
8.
Chemosphere ; 198: 174-181, 2018 May.
Artigo em Inglês | MEDLINE | ID: mdl-29421727

RESUMO

The degradation of solutions of the antibiotic levofloxacin (LVN) in sulfate medium at pH 3.0 has been investigated at pre-pilot scale by solar photoelectro-Fenton (SPEF) process. The flow plant included an FM01-LC filter-press cell equipped with a Ti|Pt anode and a three-dimensional-like air-diffusion cathode, connected to a compound parabolic collector as photoreactor and a continuous stirred tank under recirculation batch mode. The effect of volumetric flow rate on H2O2 electrogeneration from O2 reduction was assessed. Then, the influence of initial LVN concentration and Fe2+ concentration as catalyst on dissolved organic carbon (DOC) removal was thoroughly investigated. LVN was gradually mineralized by SPEF process, with faster DOC abatement at 0.50 mM Fe2+, yielding 100% after 360 min at applied cathodic potential of -0.30 V|SHE. The high mineralization current efficiency (MCE) and low specific energy consumption (ECDOC) revealed the extraordinary role of homogeneous hydroxyl radicals and natural UV light, which allowed the degradation of the antibiotic and its by-products with MCE values greater than 100%. Five cyclic by-products, N,N-diethylformamide and three short-chain linear carboxylic acids were detected by GC-MS and HPLC analyses. A parametric model to simulate the DOC decay versus electrolysis time was implemented for the SPEF pre-pilot flow plant, showing good agreement with experimental data.


Assuntos
Antibacterianos/análise , Peróxido de Hidrogênio/química , Ferro/química , Levofloxacino/análise , Modelos Teóricos , Raios Ultravioleta , Poluentes Químicos da Água/análise , Purificação da Água/métodos , Antibacterianos/efeitos da radiação , Catálise , Relação Dose-Resposta a Droga , Técnicas Eletroquímicas , Levofloxacino/efeitos da radiação , Projetos Piloto , Solubilidade , Fatores de Tempo , Poluentes Químicos da Água/efeitos da radiação
9.
Artigo em Inglês | MEDLINE | ID: mdl-29485359

RESUMO

The response of the antimicrobial compounds sulfamethoxazole (SMX) and trimethoprim (TMP) - individually and in mixtures - to ionizing radiation was investigated using laboratory prepared mixtures and a commercial pharmaceutical formulation. The residual antibacterial activity of the solutions was monitored using Staphylococcus aureus and Escherichia coli test strains. Based on antibacterial activity, SMX was more susceptible to ionizing radiation as compared to TMP. The antibacterial activity of SMX and TMP was completely eliminated at 0.2 kGy and 0.8 kGy, respectively. However, when SMX and TMP were in a mixture, the dose required to eliminate the antibacterial activity was 10 kGy, implying a synergistic antibacterial activity when these are present in mixtures. Only when the antibiotic concentration was below the Minimum Inhibitory Concentration of TMP (i.e., 2 µmol dm-3) did the antibacterial activity of the SMX and TMP mixture disappear. These results imply that the synergistic antimicrobial activity of antimicrobial compounds in pharmaceutical waste streams is a strong possibility. Therefore, antimicrobial activity assays should be included when evaluating the use of ionizing radiation technology for the remediation of pharmaceutical or municipal waste streams.


Assuntos
Bactérias/efeitos dos fármacos , Bactérias/efeitos da radiação , Radiação Ionizante , Sulfametoxazol/farmacologia , Trimetoprima/farmacologia , Antibacterianos/farmacologia , Antibacterianos/efeitos da radiação , Anti-Infecciosos/farmacologia , Anti-Infecciosos/efeitos da radiação , Bactérias/crescimento & desenvolvimento , Análise da Demanda Biológica de Oxigênio , Escherichia coli/efeitos dos fármacos , Escherichia coli/efeitos da radiação , Humanos , Testes de Sensibilidade Microbiana , Staphylococcus aureus/efeitos dos fármacos , Staphylococcus aureus/efeitos da radiação , Sulfametoxazol/efeitos da radiação , Trimetoprima/efeitos da radiação , Combinação Trimetoprima e Sulfametoxazol
10.
J Hazard Mater ; 343: 285-297, 2018 Feb 05.
Artigo em Inglês | MEDLINE | ID: mdl-28988054

RESUMO

Flexible organic fabrics coated with titania find wide applications in pollutant degradations and antibiosis. Because of the enhanced charge separations, TiO2 with one-dimensional nanostructures exhibits photocatalytic activity superior to that of nanoparticulate films; however, only the later has been achieved on organic substrates through commonly sol-gel techniques till now. In this study, radially aligned TiO2 nanowires were precipitated on polyester fabrics through multi-steps of surface roughening, sol-gel TiO2 seeding, hydrogen titanate nanobelts precipitation, and finally sulfuric acid treatment. Both mesoporous anatase TiO2 nanowires and single-crystalline rutile TiO2 nanorods have been achieved, which, together with some unchanged titanate nanobelts, exhibited an overall narrowed band gap of ca. 2.50eV. The TiO2 nanowires on flexible PET fabrics showed higher photocatalytic activity towards degradations of not only rhodamine B in water but also toluene gas in air under UV light illumination, when compared with either TiO2 nanotube array or commercial Degussa P25 nanoparticulate films on metallic Ti substrates. Remarkable sterilization of E. coli and S. epidermidis under visible light irradiation was also achieved. The excellent photocatalytic and antibacterial performances were attributed to the unique mixed 1D nanostructures, phase junctions, abundant surface hydroxyl groups, and the narrowed band gap.


Assuntos
Antibacterianos/química , Nanofios/química , Poliésteres/química , Têxteis , Titânio/química , Antibacterianos/efeitos da radiação , Catálise , Corantes/química , Escherichia coli/crescimento & desenvolvimento , Nanofios/efeitos da radiação , Processos Fotoquímicos , Poliésteres/efeitos da radiação , Rodaminas/química , Staphylococcus epidermidis/crescimento & desenvolvimento , Têxteis/efeitos da radiação , Titânio/efeitos da radiação , Raios Ultravioleta , Poluentes Químicos da Água/química
11.
Environ Sci Pollut Res Int ; 25(2): 1903-1913, 2018 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-29103120

RESUMO

Little is known about the mechanisms influencing the differences in attenuation of antibiotics between rivers. In this study, the natural attenuation of four antibiotics (azithromycin, clarithromycin, sulfapyridine, and sulfamethoxazole) during transport along the Thames River, UK, over a distance of 8.3 km, and the Katsura River, Japan, over a distance of 7.6 km was compared. To assist interpretation of the field data, the individual degradation and sorption characteristics of the antibiotics were estimated by laboratory experiments using surface water or sediment taken from the same rivers. Azithromycin, clarithromycin, and sulfapyridine were attenuated by 92, 48, and 11% in the Thames River stretch. The first-order decay constants of azithromycin and sulfapyridine were similar to those in the Katsura River, while that of clarithromycin was 4.4 times higher. For sulfamethoxazole, the attenuation was limited in both rivers. Loss of sulfapyridine was attributed to both direct and indirect photolysis in the Thames River, but to only direct photolysis in the Katsura River. Loss of azithromycin and clarithromycin was attributed to sorption to sediment in both rivers. The probable explanation behind the difference in loss rates of clarithromycin between the two rivers was considered to be sediment sorption capacity.


Assuntos
Antibacterianos/análise , Monitoramento Ambiental/métodos , Rios/química , Poluentes Químicos da Água/análise , Antibacterianos/efeitos da radiação , Sedimentos Geológicos/química , Hidrologia , Japão , Modelos Teóricos , Fotólise , Reino Unido , Poluentes Químicos da Água/efeitos da radiação
12.
Chemosphere ; 191: 1021-1027, 2018 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-29145130

RESUMO

For organic pollutants, photodegradation, as a major abiotic elimination process and of great importance to the environmental fate and risk, involves rather complicated physical and chemical processes of excited molecules. Herein, we systematically studied the photophysical and photochemical processes of a widely used antibiotic, namely sulfapyridine. By means of density functional theory (DFT) computations, we examined the rate constants and the competition of both photophysical and photochemical processes, elucidated the photochemical reaction mechanism, calculated reaction quantum yield (Φ) based on both photophysical and photochemical processes, and subsequently estimated the photodegradation rate constant. We further conducted photolysis experiments to measure the photodegradation rate constant of sulfapyridine. Our computations showed that sulfapyridine at the lowest excited singlet state (S1) mainly undergoes internal conversion to its ground state, and is difficult to transfer to the lowest excited triplet states (T1) via intersystem crossing (ISC) and emit fluorescence. In T1 state, compared with phosphorescence emission and ISC, chemical reaction is much easier to initiate. Encouragingly, the theoretically predicted photodegradation rate constant is close to the experimentally observed value, indicating that quantum chemistry computation is powerful enough to study photodegradation involving ultra-fast photophysical and photochemical processes.


Assuntos
Modelos Químicos , Processos Fotoquímicos , Fotólise , Sulfapiridina/efeitos da radiação , Antibacterianos/química , Antibacterianos/efeitos da radiação , Elétrons , Recuperação e Remediação Ambiental , Cinética , Água
13.
AAPS PharmSciTech ; 19(3): 1182-1190, 2018 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-29256152

RESUMO

The photodegradation study is essential for the phototoxicity assessment of fluoroquinolones. Various LC-MS techniques and ultraviolet (UV) lamp irradiation conditions have been used for the identification of their photodegradation products. In this study, visible light (400-760 nm) lamp irradiation was selected for the photodegradation of moxifloxacin (MOXI) hydrochloride solutions. Two photodegradation products were identified by LC-MS/MS at first, but one product could not be speculated from the mass spectrum and any known degradation mechanisms. To obtain an adequate amount for the structure elucidation, this unknown product was isolated by recrystallization and semi-preparative HPLC. Then, its structure was further identified by 1H-NMR, 13C-NMR, and 2D-NMR. Based on spectral data, this new photodegradation product was unambiguously named as 7-[3-(3-aminopropyl)-1H-pyrrol-1-yl]-1-cyclopropyl-6-fluoro-8-methoxy-4-oxo-1,4-dihydroquinoline-3-carboxylic acid, which was formed through the open of hexahydroxy N-containing heterocycle and the formation of two alkene bonds in pyrrole ring. The effects of solution pH value on the formation of photodegradation products were compared. Their production was minimum at pH 5.0 and maximum at pH 7.0. Because MOXI hydrochloride has been used extensively in clinical practice and visible light is the most possible light source that pharmaceutical products are exposed to, our study is important for the quality control of MOXI liquid preparations.


Assuntos
Antibacterianos/química , Antibacterianos/efeitos da radiação , Fluoroquinolonas/química , Fluoroquinolonas/efeitos da radiação , Cromatografia Líquida de Alta Pressão , Estabilidade de Medicamentos , Concentração de Íons de Hidrogênio , Luz , Espectroscopia de Ressonância Magnética , Moxifloxacina , Fotólise , Espectrometria de Massas em Tandem , Raios Ultravioleta
14.
Water Res ; 128: 38-48, 2018 01 01.
Artigo em Inglês | MEDLINE | ID: mdl-29078069

RESUMO

Previous studies have shown that the photodegradation of some pollutants, induced by the excited triplet states of chromophoric dissolved organic matter (3CDOM*), can be inhibited by back-reduction processes carried out by phenolic antioxidants occurring in dissolved organic matter (DOM). Here, for the first time to our knowledge, we included such an inhibition effect into a photochemical model and applied the model predictions to sulfadiazine (SDZ), a sulfonamide antibiotic that occurs in surface waters in two forms, neutral HSDZ and anionic SDZ- (pKa = 6.5). The input parameters of the photochemical model were obtained by means of dedicated experiments, which showed that the inhibition effect was more marked for SDZ- than for HSDZ. Compared to the behavior of 2,4,6-trimethylphenol, which does not undergo antioxidant inhibition when irradiated in natural water samples, the back-reduction effect on the degradation of SDZ was proportional to the electron-donating capacity of the DOM. According to the model results, direct photolysis and OH reaction would account for the majority of both HSDZ and SDZ- photodegradation in waters having low dissolved organic carbon (DOC < 1 mgC L-1). With higher DOC values (>3-4 mgC L-1) and despite the back-reduction processes, the 3CDOM* reactions are expected to account for the majority of HSDZ phototransformation. In the case of SDZ- at high DOC, most of the photodegradation would be accounted for by direct photolysis. The relative importance of the triplet-sensitized phototransformation of both SDZ- and (most importantly) HSDZ is expected to increase with increasing DOC, even in the presence of back reduction. An increase in water pH, favoring the occurrence of SDZ- with respect to HSDZ, would enhance direct photolysis at the expense of triplet sensitization. SDZ should be fairly photolabile under summertime sunlight, with predicted half-lives ranging from a few days to a couple of months depending on water conditions.


Assuntos
Antibacterianos/efeitos da radiação , Processos Fotoquímicos , Sulfadiazina/efeitos da radiação , Poluentes Químicos da Água/efeitos da radiação , Antibacterianos/análise , Antibacterianos/química , Antioxidantes/química , Meia-Vida , Fotólise , Sulfadiazina/análise , Sulfadiazina/química , Sulfonamidas , Luz Solar , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/química
15.
Artigo em Inglês | MEDLINE | ID: mdl-29240671

RESUMO

Degradation of norfloxacin (NOR) was studied using a combination of microwave and UV irradiation methods (MW/UV process). Remarkable synergistic effect was found between MW and UV light. The removal rate with the MW/UV process was much faster than that with UV light irradiation only. Degradation of NOR followed second-order kinetics and ~72% of NOR could be removed in the first 5 min of MW/UV reaction. Influence of inorganic ions (cations (K⁺, Mg2+, Ca2+, Cu2+) and anions (Cl-, SO42-, NO3-, CO32-)), humic acid (HA) and surfactants (cation, anion, and non-ionic) on the degradation of NOR by the MW/UV process was investigated. Among the ions, Cu2+ and NO3- ions inhibited the degradation of NOR. The presence of HA and surfactants in water showed a slight inhibition on the NOR removal. Furthermore, the NOR degradation in the MW/UV process was primarily caused by the ·OH-photosensitization steps. Seven intermediates formed by the oxidation of NOR were identified and three reaction pathways were proposed. Removals of NOR in tap water (TW), synthetic wastewater (WW), river water (RW), and seawater (SW) were also studied, which demonstrated that the MW/UV process was an effective oxidation technology for degrading fluoroquinolone antibiotics in different water matrices.


Assuntos
Antibacterianos/efeitos da radiação , Micro-Ondas , Norfloxacino/efeitos da radiação , Raios Ultravioleta , Poluentes Químicos da Água/efeitos da radiação , Substâncias Húmicas , Cinética , Oxirredução , Fotólise , Purificação da Água/métodos
16.
Mol Pharm ; 14(12): 4509-4514, 2017 12 04.
Artigo em Inglês | MEDLINE | ID: mdl-29111753

RESUMO

Nanostructured mesoporous silicon (pSi) derived from the silicon-accumulator plant Tabasheer (Bambuseae) is demonstrated to serve as a potential carrier matrix for carrying and stabilizing naturally active, but otherwise metastable, therapeutic agents. Particularly, in this study, garlic oil containing phytochemicals (namely, allicin) that are capable of inhibiting Staphylococcus aureus (S. aureus) bacterial growth were incorporated into Tabasheer-derived porous silicon. Thermogravimetric analysis (TGA) indicated that relatively high amounts of the extract (53.1 ± 2.2 wt %) loaded into pSi are possible by simple infiltration. Furthermore, by assessing the antibacterial activity of the samples using a combination technique of agar disk diffusion and turbidity assays against S. aureus, we report that biogenic porous silicon can be utilized to stabilize and enhance the therapeutic effects of garlic oil for up to 4 weeks when the samples were stored under refrigerated conditions (4 °C) and 1 week at room temperature (25 °C). Critically, under ultraviolet (UV) light (365 nm) irradiation for 24 h intervals, plant-derived pSi is shown to have superior performance in protecting garlic extracts over porous silica (pSiO2) derived from the same plant feedstock or extract-only controls. The mechanism for this effect has also been investigated.


Assuntos
Antibacterianos/farmacologia , Portadores de Fármacos/química , Sasa/química , Dióxido de Silício/química , Staphylococcus aureus/efeitos dos fármacos , Ácidos Sulfínicos/farmacologia , Antibacterianos/efeitos da radiação , Testes de Sensibilidade Microbiana , Nanoestruturas/química , Porosidade , Protetores contra Radiação/química , Ácidos Sulfínicos/efeitos da radiação , Propriedades de Superfície , Raios Ultravioleta/efeitos adversos
17.
Future Microbiol ; 12: 1297-1310, 2017 11.
Artigo em Inglês | MEDLINE | ID: mdl-29063786

RESUMO

AIM: Five photoactive compounds with variable elongated alkyl-substituents in a phenalen-1-one structure were examined in view of structural similarity to the antimicrobial agent benzalkonium chloride (BAC). METHODS: All phenalen-1-ones and BAC were evaluated for their antimicrobial properties against Staphylococcus aureus, methicillin-resistant S. aureus, Escherichia coli, Pseudomonas aeruginosa and for their eukaryotic toxicity against normal human epidermal keratinocyte (NHEK) cells to narrow down the BAC-like effect and the photodynamic effect depending on the chemical structure. All compounds were investigated for effective concentration ranges, where a bacterial reduction of 5 log10 is achieved, while an NHEK survival of 80% is ensured. RESULTS: Effective concentration ranges were found for four out of five photoactive compounds, but not for BAC and the compound with BAC-like alkyl chain length. CONCLUSION: Chain length size and polar area of the respective head-groups of phenalen-1-one compounds or BAC showed an influence on the incorporation inside lipid membranes and thus, head-groups may have an impact on the toxicity of antimicrobials.


Assuntos
Antibacterianos/farmacologia , Anti-Infecciosos Locais/farmacologia , Bactérias/efeitos dos fármacos , Compostos de Benzalcônio/farmacologia , Fenalenos/farmacologia , Antibacterianos/química , Antibacterianos/efeitos da radiação , Anti-Infecciosos Locais/química , Anti-Infecciosos Locais/efeitos da radiação , Compostos de Benzalcônio/química , Linhagem Celular , Membrana Celular/química , Escherichia coli/efeitos dos fármacos , Humanos , Queratinócitos/efeitos dos fármacos , Luz , Lipídeos de Membrana/química , Staphylococcus aureus Resistente à Meticilina/efeitos dos fármacos , Fenalenos/química , Fenalenos/efeitos da radiação , Pseudomonas aeruginosa/efeitos dos fármacos , Oxigênio Singlete/química , Staphylococcus aureus/efeitos dos fármacos
18.
Inorg Chem ; 56(15): 9084-9096, 2017 Aug 07.
Artigo em Inglês | MEDLINE | ID: mdl-28726387

RESUMO

Ruthenium polypyridine complexes have shown promise as agents for photodynamic therapy (PDT) and tools for molecular biology (chromophore-assisted light inactivation). To accomplish these tasks, it is important to have at least target selectivity and great reactive oxygen species (ROS) photogeneration: two properties that are not easily found in the same molecule. To prepare such new agents, we synthesized two new ruthenium complexes that combine an efficient DNA binding moiety (dppz ligand) together with naphthyl-modified (1) and anthracenyl-modified (2) bipyridine as a strong ROS generator bound to a ruthenium complex. The compounds were fully characterized and their photophysical and photochemical properties investigated. Compound 2 showed one of the highest quantum yields for singlet oxygen production ever reported (ΦΔ= 0.96), along with very high DNA binding (log Kb = 6.78). Such photochemical behavior could be ascribed to the lower triplet state involving the anthracenyl-modified bipyridine, which is associated with easier oxygen quenching. In addition, the compounds exhibited moderate selectivity toward G-quadruplex DNA and binding to the minor groove of DNA, most likely driven by the pendant ligands. Interestingly, they also showed DNA photocleavage activity even upon exposure to a yellow light-emitting diode (LED). Regarding their biological activity, the compounds exhibited an exciting antibacterial action, particularly against Gram-positive bacteria, which was enhanced upon blue LED irradiation. Altogether, these results showed that our strategy succeeded in producing light-triggered DNA binding agents with pharmacological and biotechnological potential.


Assuntos
Complexos de Coordenação/farmacologia , DNA/química , Substâncias Intercalantes/farmacologia , Rutênio/química , 2,2'-Dipiridil/síntese química , 2,2'-Dipiridil/química , 2,2'-Dipiridil/farmacologia , 2,2'-Dipiridil/efeitos da radiação , Antracenos/síntese química , Antracenos/química , Antracenos/farmacologia , Antracenos/efeitos da radiação , Antibacterianos/síntese química , Antibacterianos/química , Antibacterianos/farmacologia , Antibacterianos/efeitos da radiação , Complexos de Coordenação/síntese química , Complexos de Coordenação/química , Complexos de Coordenação/efeitos da radiação , Dano ao DNA , Etídio/farmacologia , Bactérias Gram-Positivas/efeitos dos fármacos , Substâncias Intercalantes/síntese química , Substâncias Intercalantes/química , Substâncias Intercalantes/efeitos da radiação , Ligantes , Luz , Oxigênio/química , Fármacos Fotossensibilizantes/síntese química , Fármacos Fotossensibilizantes/química , Fármacos Fotossensibilizantes/farmacologia , Fármacos Fotossensibilizantes/efeitos da radiação , Espécies Reativas de Oxigênio/síntese química
19.
J Hazard Mater ; 340: 160-170, 2017 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-28715739

RESUMO

A photocatalytic sol of TiO2 nanoparticles has been used for creating self-cleaning antimicrobial flat and porous glass surfaces. The substrates were irradiated to study their photocatalytic properties and behavior in the presence of biofilm-forming bacteria. Smooth glass surfaces and glass microfiber filters were covered with 1.98×10-3±1.5×10-4gcm-2 and 8.55×10-3±3.0×10-4gcm-2 densities, respectively. Self-cleaning properties were analyzed using the methylene blue 365nm UV-A photodegradation test. TiO2-coated filters achieved rapid and complete photodegradation of methylene blue because of the better TiO2 dispersion with respect to the glass slides. The effect of functionalized surfaces on the growth and viability of bacteria was studied using the strains Staphylococcus aureus and Pseudomonas putida. After irradiation (2h, 11.2Wm-2, 290-400nm), the initially hydrophobic surface turned hydrophilic. The antibacterial effect led to extensive membrane damage and significant production of intracellular reactive oxygen species in all TiO2-loaded irradiated specimens. The reduction of cell viability was over 99.9% (>3-log) for TiO2 on glass surfaces. However, the polymeric extracellular matrix formed before the irradiation treatment was not removed. This study highlights the importance of bacterial colonization during dark periods and the difficulty of removing the structure of biofilms.


Assuntos
Antibacterianos , Biofilmes/efeitos dos fármacos , Nanopartículas , Pseudomonas putida/efeitos dos fármacos , Staphylococcus aureus/efeitos dos fármacos , Titânio , Raios Ultravioleta , Antibacterianos/química , Antibacterianos/farmacologia , Antibacterianos/efeitos da radiação , Catálise , Matriz Extracelular/efeitos dos fármacos , Azul de Metileno/química , Nanopartículas/química , Nanopartículas/efeitos da radiação , Fotólise , Pseudomonas putida/crescimento & desenvolvimento , Pseudomonas putida/fisiologia , Staphylococcus aureus/crescimento & desenvolvimento , Staphylococcus aureus/fisiologia , Propriedades de Superfície , Titânio/química , Titânio/farmacologia , Titânio/efeitos da radiação
20.
Molecules ; 22(6)2017 Jun 09.
Artigo em Inglês | MEDLINE | ID: mdl-28598370

RESUMO

The most effective means to protect against bacterial invasion and to reduce the risk of healthcare-associated infections are antibacterial components synthesis. In this study, a novel process for the synthesis of organic-inorganic hybrid coatings containing silver nanoparticles is presented. Silver nanoparticles and polymer formation proceeds simultaneously through the in situ photoreduction of silver salt to silver nanoparticles and UV-crosslinking of bifunctional aliphatic silicone acrylate. The nanocomposite films with 0.5-1.43 wt % of silver nanoparticles concentration were obtained and investigated. The formation of silver nanoparticles in polymer matrix was confirmed via UV-visible spectroscopy, X-ray diffraction (XRD), Fourier transform infrared spectroscopy, scanning electron spectroscopy, and energy dispersive spectroscopy. Our investigations clearly show the formation of silver nanoparticles in silicone acrylate network. Direct photoreduction of silver salt by UV-radiation in the organic media produced silver nanoparticles exhibiting cubic crystal structure. The size of nanoparticles was determined to be near 20 ± 5 nm. The antibacterial activities of coatings were determined using the disc diffusion and direct contact methods. UV-curable silicone acrylate hybrid coatings exhibited antibacterial activity against harmful bacteria strains.


Assuntos
Acrilatos/química , Antibacterianos/química , Materiais Revestidos Biocompatíveis/química , Nanopartículas Metálicas/química , Silício/química , Prata/química , Antibacterianos/farmacologia , Antibacterianos/efeitos da radiação , Materiais Revestidos Biocompatíveis/farmacologia , Materiais Revestidos Biocompatíveis/efeitos da radiação , Escherichia coli/efeitos dos fármacos , Escherichia coli/crescimento & desenvolvimento , Nanopartículas Metálicas/ultraestrutura , Testes de Sensibilidade Microbiana , Oxirredução , Processos Fotoquímicos , Prata/farmacologia , Staphylococcus aureus/efeitos dos fármacos , Staphylococcus aureus/crescimento & desenvolvimento , Propriedades de Superfície , Raios Ultravioleta
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