N. Bogdanchikova | Universidad Nacional Autónoma de México (original) (raw)
Papers by N. Bogdanchikova
Cytogenetic and Genome Research, 2002
B chromosomes of Korean field mouse Apodemus peninsulae (Rodentia, Murinae) analysed by microdiss... more B chromosomes of Korean field mouse Apodemus peninsulae (Rodentia, Murinae) analysed by microdissection and FISH Karamysheva TV, Andreenkova OV, Bochkaerev MN, Borissov YM, Bogdanchikova N, Borodin PM, Rubtsov NB 161 Sex chromosomes and sex determination in weird mammals Marshall Graves JA 169 Mapping the distribution of the telomeric sequence (T 2 AG 3) n in rock wallabies, Petrogale (Marsupialia: Macropodidae), by fluorescence in situ hybridization. II. The lateralis complex Metcalfe CJ, Eldridge MDB, Johnston PG 176 Conservation of avian Z chromosomes as revealed by comparative mapping of the Z-linked aldolase B gene Nanda I, Schmid M 179 Copy and paste: the impact of a new non-L1 retroposon on the gonosomal heterochromatin of Microtus agrestis
PLOS ONE, 2021
SARS-CoV-2 infection in hospital areas is of a particular concern, since the close interaction be... more SARS-CoV-2 infection in hospital areas is of a particular concern, since the close interaction between health care personnel and patients diagnosed with COVID-19, which allows virus to be easily spread between them and subsequently to their families and communities. Preventing SARS-CoV-2 infection among healthcare personnel is essential to reduce the frequency of infections and outbreaks during the pandemic considering that they work in high-risk areas. In this research, silver nanoparticles (AgNPs) were tested in vitro and shown to have an inhibitory effect on SARS-CoV-2 infection in cultured cells. Subsequently, we assess the effects of mouthwash and nose rinse with ARGOVIT® silver nanoparticles (AgNPs), in the prevention of SARS-CoV-2 contagion in health workers consider as high-risk group of acquiring the infection in the General Tijuana Hospital, Mexico, a hospital for the exclusive recruitment of patients diagnosed with COVID-19. We present a prospective randomized study of 23...
Cytogenetic and Genome Research, 2002
Karl Fredga dedication volume This volume is dedicated to Karl Fredga by his friends and associat... more Karl Fredga dedication volume This volume is dedicated to Karl Fredga by his friends and associates to commemorate his retirement and lifelong cytogenetic research activities
Toxicology Letters, 2016
Introduction: The use of nanoparticles (NPs) is among the most promising strategies to overcome i... more Introduction: The use of nanoparticles (NPs) is among the most promising strategies to overcome infections within the medical and dental area. Bismuth subsalicylate (BSS) has been used as an antimicrobial agent against H. pylori infections. However, there is not enough information regarding the antibacterial effect of BBS-NPs in other relevant bacteria strains and their toxic effects in mammalian cells. Objective: The aim of this study was to evaluate the in vitro cytotoxicity of BSS-NPs against cultures of four strains of bacteria of medical importance and in cell cultures of human gingival fibroblast. Materials and methods: BSS-NPs were synthesized by laser ablation and the physico-chemical characterization was performed by UV-Vis spectroscopy, Dynamic light scattering (LDS), Laser Doppler Anemometer (LDA) and Transmission Electron Microscopy (TEM). To evaluate the antibacterial effect, BSS-NPs were tested against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Staphylococcus epidermidis using XTT assay in 24 h. Cell cultures of human gingival fibroblast (HGF-1) were used to measure cell viability by MTS and LDH assays for 24 h. Results: The UV-Vis spectra indicated the presence of salicylic acid functional groups that are present in the BSS chemical structure. LDS measurement reported a diameter in water of between 1.2 and 220 nm and the zeta potential of −9.09 which was obtained by LDA. The use of TEM allowed to observe nanoparticles, with a crystal structure and primary particle size of 10 nm. The results of antibacterial effect indicated a significant growth inhibition in all strains tested (∼89%), being more effective against P. aeruginosa with a 90% at a concentration of 60 g/mL of BSS-NPs. Cell viability assays showed that BSS-NPs did not compromise HGF-1 viability, 96% of mitochondrial activity and 5% of LDH release was observed at 60 g/mL. Conclusions: BSS-NPs showed an efficient antibacterial effect in bacteria strains of dental importance and a low toxicity in cell mammalian cultures; thus BBS-NPs could be a good antimicrobial agent for medical-dental applications.
Colloid and Interface Science Communications, 2022
Studies in Surface Science and Catalysis, 1991
Abstract Original methods of synthesis of highly dispersed silver catalysts (based upon the appli... more Abstract Original methods of synthesis of highly dispersed silver catalysts (based upon the application of strong reducing properties of electrons solvated in soldium-ammonia solutions, the adsorption-contact method of drying and a weak solubility in nitric acid of the SiO 2 -supported small silver clusters) allowed us to synthesize SiO 2 -supported silver particles of sizes less than 6 nm. It makes possible some unusual catalytic and other physico-chemical properties of these particles to be discovered.
Features of the process of methanol partial oxidation on supported gold catalysts as compared wit... more Features of the process of methanol partial oxidation on supported gold catalysts as compared with Ag and Cu catalysts have been studied. The influence of electronic states of supported gold was investigated by the methods of diffuse reflectance electron spectroscopy, XRD and electron microscopy. By comparison of catalytic and spectroscopic data it was concluded that univalent Au + ions are the active sites of the gold catalysts in alcohol partial oxidation. Modifiers stabilizing the ionic states of gold (Ce and Zr oxides) increase the selectivity of the catalyst, whereas elec- tron-releasing additions (La and Cs oxides) impair the catalyst properties.
Experimental Parasitology, 2020
Ciliate ectoparasites are one of the most important groups of pathogens in fish culture, and the ... more Ciliate ectoparasites are one of the most important groups of pathogens in fish culture, and the traditional treatments are sometimes harmful to the fish and the environment. Thus, the search for novel compounds that are effective at low concentrations and safe for fish are necessary to optimise treatments in aquaculture. The antiprotozoal capacity of silver nanoparticles (AgNPs) against the ciliate Tetrahymena has been documented; however, their toxicity may vary with the synthesis methodology and nanoparticle size. The objectives of this study were a) to evaluate the acute toxicity in vitro of two AgNPs (Argovit™ and UTSA) on Tetrahymena sp., a biological model for ciliated ectoparasites of fish and b) to test the safety of lethal and higher doses of UTSA AgNPs for ciliates on the fish C. estor. Light microscopy and scanning electron microscopy (SEM) were used to determine whether AgNPs affected the structure of the cell surface of Tetrahymena. The mortality, histopathological alterations and metagenomics of the fish were used to determine the major effects of UTSA AgNPs. In Tetrahymena, the median lethal concentration (LC 50) for Argovit™ was 2501 ± 1717 ng/L at 15 min and 796 ± 510 ng/L at 60 min, while the LC 50 for UTSA AgNPs was 4 ± 2 and 1 ± 0.6 ng/L at 15 min and 60 min, respectively. A concentration of 3300 ng/L Argovit™ and 10.6 ng/L UTSA AgNPs for 15 and 60 min, respectively, was 100% effective against Tetrahymena. After 60 min of exposure to 0.25 and 0.50 ng/L UTSA AgNPs, the number of cilia significantly reduced, there were small holes on the cell surface, and the cellular membrane was ruptured. In fish exposed to lethal (10.6 ng/L) and higher (31.8 and 95.4 ng/L) doses of UTSA, the AgNPs did not affect fish survival after 96 h, and there were no signs of histopathological damage or gut microbial changes. This study is the first report on microscopic and ultrastructural changes in Tetrahymena after exposure to significantly low concentrations of UTSA AgNPs with antiprotozoal efficacy without evidence of harmful effects on fish. These results provide the basis for further studies of both pet aquarium and commercial fish that may validate these findings at a larger experimental scale, taking into account AgNPs bioaccumulation, safety for human consumption and environmental impact.
Fuel, 2019
A novel route to prepare monodispersed 1-2 nm gold nanoparticles (NPs), based on the use of extre... more A novel route to prepare monodispersed 1-2 nm gold nanoparticles (NPs), based on the use of extremely small SiO 2 NPs (2-4 nm) as a support and increasing their metal-support interaction with surface modifier oxides is presented. The influence of modifier (La, Ce and Fe oxides) and modification method (impregnation (i) or direct synthesis (s)) on the formation of ultra-small Au NPs and their structural and electronic properties was studied. The samples were characterized by N 2 adsorption (BET), FTIR of adsorbed CO, XRD and HR-TEM methods, and tested for the catalytic selective oxidation of 1-octanol. Preparation of monodispersed Au NPs with 1 nm diameter was successfully achieved for all the modified samples studied, with exception of Au/Ce/SiO 2-i, where CeO 2 was not homogeneously distributed. The Au NPs have high degree of monodispersity and are stable when treated in H 2 up to 300°C. Formation of these Au NPs depended on the strong interactions between the cationic gold complex precursor and the surface of modified SiO 2 NPs. Modifiers changed electronic properties of supported gold; favoring the formation and stabilization of Au δ+ states, which are probable gold active sites of selective liquid-phase oxidation of alcohols in redox catalytic processes. 1-octanol oxidation was used as a model reaction for oxidation of fatty alcohols obtained during biomass transformation. The best performance for 1octanol oxidation was found for gold nanoparticles supported on the ultra-small SiO 2 modified cerium oxide by impregnation method. The relative order of activity was: AuCeSiO 2-i > AuFeSiO 2-i ≫ AuLaSiO 2-i ≈ AuLaSiO 2s > AuSiO 2 > AuFeSiO 2-s≫ AuCeSiO 2-s. The obtained results open the possibility of further development of high-performance catalysts for conversion of secondary products of biomass processing into valuable chemicals.
Journal of Molecular Catalysis A: Chemical, 2017
This is a PDF file of an unedited manuscript that has been accepted for publication. As a service... more This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. n-Octanol oxidation on Au/TiO2 catalysts promoted with La and Ce oxides
ABSTRACT Infectious diseases represent a public health challenge worldwide. Conventional antimicr... more ABSTRACT Infectious diseases represent a public health challenge worldwide. Conventional antimicrobial agents are one of the factors for the development of multiple drug resistance and adverse side effects; therefore the development of new antibiotics and treatments is a global need. Candidiasis is the most common fungal disease, having a rapid increment of its prevalence. This disease is caused by the dimorphic yeast Candida spp., with Candida albicans as the main agent causing the infection. Several species of Candida are reported to present resistance to antifungal agents, representing a health problem that affects mainly immunocompromised patients. Silver has long been recognized for its antimicrobial effects and recently, silver nanoparticles have been reported to have antifungal properties. Therefore, in this study, we used silver nanoparticles (AgNPs) of 3-10 nm to assess their effect against Candida albicans. Preliminary results show high antifungal activity at very low concentrations (3.15 μg/mL), lower than those of common antifungal agents. However, the mechanism of action of AgNPs has not been truly elucidated, so more research is needed to understand the way AgNPs interact with the living cell and how to improve their use in the clinic. For that, the next step will be to determine the ultrastructural distribution of AgNPs in the fungal cell, and the effect of AgNPs in Candida´s clinical isolates.
Catalysis Today, 2004
Catalysts based on silver supported on foam ceramics and modified by Zr, Ce and La oxides have be... more Catalysts based on silver supported on foam ceramics and modified by Zr, Ce and La oxides have been studied in the process of partial oxidation of methanol to formaldehyde. The foam catalysts exhibit high catalytic, mechanical and gas-dynamic properties exceeding the chara cteristics of conventional crystalline and supported silver samples. Modifying additives of Zr and Ce oxides raise activity and selectivity of the supported foam-silver catalyst as well as its stability during the prolonged functioning. The modifiers change the electronic state and redox properties of silver, the metal dispersivity, surface diffusion and aggregation of silver during the long-term service.
Processes, 2020
Gold nanoparticles supported on various oxides (CeO2, CeO2/TiO2, MgO, MgO/TiO2, La2O3, La2O3/TiO2... more Gold nanoparticles supported on various oxides (CeO2, CeO2/TiO2, MgO, MgO/TiO2, La2O3, La2O3/TiO2) (with 4 wt.% Au loading) were investigated in the liquid (aqueous) phase oxidation of glycerol by molecular oxygen under mild conditions, in the presence of alkaline earth (CaO, SrO and MgO) or alkaline (NaOH) bases. Full conversion and selectivity between 38 and 68% to sodium glycerate were observed on different Au supported catalysts (Au/MgO/TiO2, Au/La2O3/TiO2, Au/CeO2 and Au/CeO2/TiO2). The combined effect of Au particle size and basicity of the support was suggested as the determining factor of the activity. Agglomeration of gold nanoparticles, found after the reaction, led to the deactivation of the catalysts, which prevents the further oxidation of sodium glycerate into sodium tartronate. Promising results were obtained with the use of alkaline earth bases (CaO, SrO, MgO), leading to the formation of free carboxylic acids instead of salts, which are formed in the presence of the...
Catalysis Today, 2021
Abstract Liquid-phase oxidation of betulin extracted from birch bark was studied over gold cataly... more Abstract Liquid-phase oxidation of betulin extracted from birch bark was studied over gold catalysts supported on a range of supports (hydrotalcite, ZrO2, ZnO, MgO, CeO2, La2O3, HMS and various alumina) with different morphology and properties. Gold catalysts as well as the corresponding supports were characterized by XRD, BET, ICP-OES, XPS and TEM. It was found that the nature of the support plays a decisive role in betulin oxidation over gold-based catalysts, expressed in the influence on the average size and distribution of gold nanoparticles and, thereby, on their catalytic performance (activity and selectivity) in betulin oxidation. Moreover, it was revealed that betulin oxidation catalyzed by gold is a structure sensitive reaction, requiring an optimal size of gold nanoparticles of ca. 3.3 nm. The most suitable support for gold was found to be alumina. Kinetic studies allowed determination of reaction orders and conditions favorable for selective formation of a particular oxo-derivative of betulin (betulone, betulinic and betulonic aldehydes, betulinic acid).
Journal of Applied Research and Technology, 2021
Foot infections are difficult to eradicate, patients with diabetes mellitus among others are more... more Foot infections are difficult to eradicate, patients with diabetes mellitus among others are more susceptible to them, therefore preventive strategies and effective antimicrobial agents are needed. The antimicrobial properties of silver nanoparticles (AgNPs) are well known thus they are a trend for biomedical applications. The aim of this study was to investigate the antibacterial and antifungal activity of leather coated with AgNPs against two bacteria species Pseudomonas mendocina and Pseudomonas syringae, and the fungi Trichophyton mentagrophytes responsible for foot infections. Porcine leather was cut off and sprinkled with solutions containing various concentrations of metallic AgNPs. Inductively coupled plasma-atomic emission spectrometry (ICP-AES) and texture analysis of the leather were performed to quantify the silver metallic concentration metallic silver and to test the effect of AgNPs on leather softness. Antimicrobial activity was measured by agar diffusion test for zon...
Mishra/Application, 2014
Je voudrais tout d'abord remercier mes directeurs de thèse, François VERDIER et Benoit MIRAMOND d... more Je voudrais tout d'abord remercier mes directeurs de thèse, François VERDIER et Benoit MIRAMOND dont les conseils et les remarques m'ontété utiles pour menerà bien ce projet. Merciégalement aux membres du jury qui m'ont fait l'honneur d'évaluer mon travail, Guy GOGNIAT et Daniel CHILLET qui ont accepté d'enêtre les rapporteurs, Samy MEFTALI et Bertrand GRANADO qui en ontété les examinateurs. Je tiensà remercier Lounis KESSAL et Mahmoud KARABERNOU pour leur soutien et leur bonne humeur tout au long de ces années. Je tiens en particulierà remercier mes collègues de bureau, Laurent GANTEL, qui a toujoursété là pour m'encourager et avec qui j'ai passé d'excellents moments. Je le remercie aussi bien pour son soutien moral que pour son apport scientifique, pour sa disponibilité et son amitié. Un grand mercià Liang Zhou, qui est une femme remarquable, mère et thésardeà la fois. Merciégalementà Lounis Zerioul pour sa présence et ses encouragements, Mohemmed HAMIA, Guy WASSI, et Christian GAMON, qui ont aussí eté très présents et qui sont devenus au fil du temps de véritables amis. Une part de ces remerciements va aux membres du projet FOSFOR avec lesquels j'ai travaillé régulièrement : Fabrice MULLER, Daniel CHILLET, Sébastien PILLEMENT, Lounis KESSAL et Nicolas KNECHT. Enfin je souhaite exprimer toute ma gratitude envers mes parents sans lesquels je n'en serais pas là aujourd'hui, mon oncle Rachid, ma grand-mère MAMIE, mes frères et soeurs, mes amis : Wafaé, Dahlia, Habiba, Imene, Amina, Youcef et tous mes proches pour leur présence et leur soutien durant toutes ces années.
Journal of Nanoscience and Nanotechnology, 2011
Supporting silver and gold on mordenites by ion-exchange method with further reduction with H2 le... more Supporting silver and gold on mordenites by ion-exchange method with further reduction with H2 leads to formation of neutral and charged metal clusters inside zeolite channels as well as metal nanoparticles on external surface of mordenite. A portion of the cluster states of the metals and stability of the clusters depend strongly on acidity of zeolite (determined by SiO2/Al2O3 molar ratio) and nature of zeolite cation (H+, Na+, NH4+). The investigations of silver and gold samples after prolonged storage for 6 and 12 months revealed that silver clusters are comparatively stable while oxidation of gold clusters and nanoparticles by air is the probable cause of deactivation of gold catalysts. The comparison of the results for Au and Ag samples allow suggesting NaM15 and NaM24 mordenites for effective synthesis of complex Au-Ag clusters as active and stable species of catalytic reactions occurring at room temperature.
Applied Catalysis A: General, 2011
Cytogenetic and Genome Research, 2002
B chromosomes of Korean field mouse Apodemus peninsulae (Rodentia, Murinae) analysed by microdiss... more B chromosomes of Korean field mouse Apodemus peninsulae (Rodentia, Murinae) analysed by microdissection and FISH Karamysheva TV, Andreenkova OV, Bochkaerev MN, Borissov YM, Bogdanchikova N, Borodin PM, Rubtsov NB 161 Sex chromosomes and sex determination in weird mammals Marshall Graves JA 169 Mapping the distribution of the telomeric sequence (T 2 AG 3) n in rock wallabies, Petrogale (Marsupialia: Macropodidae), by fluorescence in situ hybridization. II. The lateralis complex Metcalfe CJ, Eldridge MDB, Johnston PG 176 Conservation of avian Z chromosomes as revealed by comparative mapping of the Z-linked aldolase B gene Nanda I, Schmid M 179 Copy and paste: the impact of a new non-L1 retroposon on the gonosomal heterochromatin of Microtus agrestis
PLOS ONE, 2021
SARS-CoV-2 infection in hospital areas is of a particular concern, since the close interaction be... more SARS-CoV-2 infection in hospital areas is of a particular concern, since the close interaction between health care personnel and patients diagnosed with COVID-19, which allows virus to be easily spread between them and subsequently to their families and communities. Preventing SARS-CoV-2 infection among healthcare personnel is essential to reduce the frequency of infections and outbreaks during the pandemic considering that they work in high-risk areas. In this research, silver nanoparticles (AgNPs) were tested in vitro and shown to have an inhibitory effect on SARS-CoV-2 infection in cultured cells. Subsequently, we assess the effects of mouthwash and nose rinse with ARGOVIT® silver nanoparticles (AgNPs), in the prevention of SARS-CoV-2 contagion in health workers consider as high-risk group of acquiring the infection in the General Tijuana Hospital, Mexico, a hospital for the exclusive recruitment of patients diagnosed with COVID-19. We present a prospective randomized study of 23...
Cytogenetic and Genome Research, 2002
Karl Fredga dedication volume This volume is dedicated to Karl Fredga by his friends and associat... more Karl Fredga dedication volume This volume is dedicated to Karl Fredga by his friends and associates to commemorate his retirement and lifelong cytogenetic research activities
Toxicology Letters, 2016
Introduction: The use of nanoparticles (NPs) is among the most promising strategies to overcome i... more Introduction: The use of nanoparticles (NPs) is among the most promising strategies to overcome infections within the medical and dental area. Bismuth subsalicylate (BSS) has been used as an antimicrobial agent against H. pylori infections. However, there is not enough information regarding the antibacterial effect of BBS-NPs in other relevant bacteria strains and their toxic effects in mammalian cells. Objective: The aim of this study was to evaluate the in vitro cytotoxicity of BSS-NPs against cultures of four strains of bacteria of medical importance and in cell cultures of human gingival fibroblast. Materials and methods: BSS-NPs were synthesized by laser ablation and the physico-chemical characterization was performed by UV-Vis spectroscopy, Dynamic light scattering (LDS), Laser Doppler Anemometer (LDA) and Transmission Electron Microscopy (TEM). To evaluate the antibacterial effect, BSS-NPs were tested against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Staphylococcus epidermidis using XTT assay in 24 h. Cell cultures of human gingival fibroblast (HGF-1) were used to measure cell viability by MTS and LDH assays for 24 h. Results: The UV-Vis spectra indicated the presence of salicylic acid functional groups that are present in the BSS chemical structure. LDS measurement reported a diameter in water of between 1.2 and 220 nm and the zeta potential of −9.09 which was obtained by LDA. The use of TEM allowed to observe nanoparticles, with a crystal structure and primary particle size of 10 nm. The results of antibacterial effect indicated a significant growth inhibition in all strains tested (∼89%), being more effective against P. aeruginosa with a 90% at a concentration of 60 g/mL of BSS-NPs. Cell viability assays showed that BSS-NPs did not compromise HGF-1 viability, 96% of mitochondrial activity and 5% of LDH release was observed at 60 g/mL. Conclusions: BSS-NPs showed an efficient antibacterial effect in bacteria strains of dental importance and a low toxicity in cell mammalian cultures; thus BBS-NPs could be a good antimicrobial agent for medical-dental applications.
Colloid and Interface Science Communications, 2022
Studies in Surface Science and Catalysis, 1991
Abstract Original methods of synthesis of highly dispersed silver catalysts (based upon the appli... more Abstract Original methods of synthesis of highly dispersed silver catalysts (based upon the application of strong reducing properties of electrons solvated in soldium-ammonia solutions, the adsorption-contact method of drying and a weak solubility in nitric acid of the SiO 2 -supported small silver clusters) allowed us to synthesize SiO 2 -supported silver particles of sizes less than 6 nm. It makes possible some unusual catalytic and other physico-chemical properties of these particles to be discovered.
Features of the process of methanol partial oxidation on supported gold catalysts as compared wit... more Features of the process of methanol partial oxidation on supported gold catalysts as compared with Ag and Cu catalysts have been studied. The influence of electronic states of supported gold was investigated by the methods of diffuse reflectance electron spectroscopy, XRD and electron microscopy. By comparison of catalytic and spectroscopic data it was concluded that univalent Au + ions are the active sites of the gold catalysts in alcohol partial oxidation. Modifiers stabilizing the ionic states of gold (Ce and Zr oxides) increase the selectivity of the catalyst, whereas elec- tron-releasing additions (La and Cs oxides) impair the catalyst properties.
Experimental Parasitology, 2020
Ciliate ectoparasites are one of the most important groups of pathogens in fish culture, and the ... more Ciliate ectoparasites are one of the most important groups of pathogens in fish culture, and the traditional treatments are sometimes harmful to the fish and the environment. Thus, the search for novel compounds that are effective at low concentrations and safe for fish are necessary to optimise treatments in aquaculture. The antiprotozoal capacity of silver nanoparticles (AgNPs) against the ciliate Tetrahymena has been documented; however, their toxicity may vary with the synthesis methodology and nanoparticle size. The objectives of this study were a) to evaluate the acute toxicity in vitro of two AgNPs (Argovit™ and UTSA) on Tetrahymena sp., a biological model for ciliated ectoparasites of fish and b) to test the safety of lethal and higher doses of UTSA AgNPs for ciliates on the fish C. estor. Light microscopy and scanning electron microscopy (SEM) were used to determine whether AgNPs affected the structure of the cell surface of Tetrahymena. The mortality, histopathological alterations and metagenomics of the fish were used to determine the major effects of UTSA AgNPs. In Tetrahymena, the median lethal concentration (LC 50) for Argovit™ was 2501 ± 1717 ng/L at 15 min and 796 ± 510 ng/L at 60 min, while the LC 50 for UTSA AgNPs was 4 ± 2 and 1 ± 0.6 ng/L at 15 min and 60 min, respectively. A concentration of 3300 ng/L Argovit™ and 10.6 ng/L UTSA AgNPs for 15 and 60 min, respectively, was 100% effective against Tetrahymena. After 60 min of exposure to 0.25 and 0.50 ng/L UTSA AgNPs, the number of cilia significantly reduced, there were small holes on the cell surface, and the cellular membrane was ruptured. In fish exposed to lethal (10.6 ng/L) and higher (31.8 and 95.4 ng/L) doses of UTSA, the AgNPs did not affect fish survival after 96 h, and there were no signs of histopathological damage or gut microbial changes. This study is the first report on microscopic and ultrastructural changes in Tetrahymena after exposure to significantly low concentrations of UTSA AgNPs with antiprotozoal efficacy without evidence of harmful effects on fish. These results provide the basis for further studies of both pet aquarium and commercial fish that may validate these findings at a larger experimental scale, taking into account AgNPs bioaccumulation, safety for human consumption and environmental impact.
Fuel, 2019
A novel route to prepare monodispersed 1-2 nm gold nanoparticles (NPs), based on the use of extre... more A novel route to prepare monodispersed 1-2 nm gold nanoparticles (NPs), based on the use of extremely small SiO 2 NPs (2-4 nm) as a support and increasing their metal-support interaction with surface modifier oxides is presented. The influence of modifier (La, Ce and Fe oxides) and modification method (impregnation (i) or direct synthesis (s)) on the formation of ultra-small Au NPs and their structural and electronic properties was studied. The samples were characterized by N 2 adsorption (BET), FTIR of adsorbed CO, XRD and HR-TEM methods, and tested for the catalytic selective oxidation of 1-octanol. Preparation of monodispersed Au NPs with 1 nm diameter was successfully achieved for all the modified samples studied, with exception of Au/Ce/SiO 2-i, where CeO 2 was not homogeneously distributed. The Au NPs have high degree of monodispersity and are stable when treated in H 2 up to 300°C. Formation of these Au NPs depended on the strong interactions between the cationic gold complex precursor and the surface of modified SiO 2 NPs. Modifiers changed electronic properties of supported gold; favoring the formation and stabilization of Au δ+ states, which are probable gold active sites of selective liquid-phase oxidation of alcohols in redox catalytic processes. 1-octanol oxidation was used as a model reaction for oxidation of fatty alcohols obtained during biomass transformation. The best performance for 1octanol oxidation was found for gold nanoparticles supported on the ultra-small SiO 2 modified cerium oxide by impregnation method. The relative order of activity was: AuCeSiO 2-i > AuFeSiO 2-i ≫ AuLaSiO 2-i ≈ AuLaSiO 2s > AuSiO 2 > AuFeSiO 2-s≫ AuCeSiO 2-s. The obtained results open the possibility of further development of high-performance catalysts for conversion of secondary products of biomass processing into valuable chemicals.
Journal of Molecular Catalysis A: Chemical, 2017
This is a PDF file of an unedited manuscript that has been accepted for publication. As a service... more This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. n-Octanol oxidation on Au/TiO2 catalysts promoted with La and Ce oxides
ABSTRACT Infectious diseases represent a public health challenge worldwide. Conventional antimicr... more ABSTRACT Infectious diseases represent a public health challenge worldwide. Conventional antimicrobial agents are one of the factors for the development of multiple drug resistance and adverse side effects; therefore the development of new antibiotics and treatments is a global need. Candidiasis is the most common fungal disease, having a rapid increment of its prevalence. This disease is caused by the dimorphic yeast Candida spp., with Candida albicans as the main agent causing the infection. Several species of Candida are reported to present resistance to antifungal agents, representing a health problem that affects mainly immunocompromised patients. Silver has long been recognized for its antimicrobial effects and recently, silver nanoparticles have been reported to have antifungal properties. Therefore, in this study, we used silver nanoparticles (AgNPs) of 3-10 nm to assess their effect against Candida albicans. Preliminary results show high antifungal activity at very low concentrations (3.15 μg/mL), lower than those of common antifungal agents. However, the mechanism of action of AgNPs has not been truly elucidated, so more research is needed to understand the way AgNPs interact with the living cell and how to improve their use in the clinic. For that, the next step will be to determine the ultrastructural distribution of AgNPs in the fungal cell, and the effect of AgNPs in Candida´s clinical isolates.
Catalysis Today, 2004
Catalysts based on silver supported on foam ceramics and modified by Zr, Ce and La oxides have be... more Catalysts based on silver supported on foam ceramics and modified by Zr, Ce and La oxides have been studied in the process of partial oxidation of methanol to formaldehyde. The foam catalysts exhibit high catalytic, mechanical and gas-dynamic properties exceeding the chara cteristics of conventional crystalline and supported silver samples. Modifying additives of Zr and Ce oxides raise activity and selectivity of the supported foam-silver catalyst as well as its stability during the prolonged functioning. The modifiers change the electronic state and redox properties of silver, the metal dispersivity, surface diffusion and aggregation of silver during the long-term service.
Processes, 2020
Gold nanoparticles supported on various oxides (CeO2, CeO2/TiO2, MgO, MgO/TiO2, La2O3, La2O3/TiO2... more Gold nanoparticles supported on various oxides (CeO2, CeO2/TiO2, MgO, MgO/TiO2, La2O3, La2O3/TiO2) (with 4 wt.% Au loading) were investigated in the liquid (aqueous) phase oxidation of glycerol by molecular oxygen under mild conditions, in the presence of alkaline earth (CaO, SrO and MgO) or alkaline (NaOH) bases. Full conversion and selectivity between 38 and 68% to sodium glycerate were observed on different Au supported catalysts (Au/MgO/TiO2, Au/La2O3/TiO2, Au/CeO2 and Au/CeO2/TiO2). The combined effect of Au particle size and basicity of the support was suggested as the determining factor of the activity. Agglomeration of gold nanoparticles, found after the reaction, led to the deactivation of the catalysts, which prevents the further oxidation of sodium glycerate into sodium tartronate. Promising results were obtained with the use of alkaline earth bases (CaO, SrO, MgO), leading to the formation of free carboxylic acids instead of salts, which are formed in the presence of the...
Catalysis Today, 2021
Abstract Liquid-phase oxidation of betulin extracted from birch bark was studied over gold cataly... more Abstract Liquid-phase oxidation of betulin extracted from birch bark was studied over gold catalysts supported on a range of supports (hydrotalcite, ZrO2, ZnO, MgO, CeO2, La2O3, HMS and various alumina) with different morphology and properties. Gold catalysts as well as the corresponding supports were characterized by XRD, BET, ICP-OES, XPS and TEM. It was found that the nature of the support plays a decisive role in betulin oxidation over gold-based catalysts, expressed in the influence on the average size and distribution of gold nanoparticles and, thereby, on their catalytic performance (activity and selectivity) in betulin oxidation. Moreover, it was revealed that betulin oxidation catalyzed by gold is a structure sensitive reaction, requiring an optimal size of gold nanoparticles of ca. 3.3 nm. The most suitable support for gold was found to be alumina. Kinetic studies allowed determination of reaction orders and conditions favorable for selective formation of a particular oxo-derivative of betulin (betulone, betulinic and betulonic aldehydes, betulinic acid).
Journal of Applied Research and Technology, 2021
Foot infections are difficult to eradicate, patients with diabetes mellitus among others are more... more Foot infections are difficult to eradicate, patients with diabetes mellitus among others are more susceptible to them, therefore preventive strategies and effective antimicrobial agents are needed. The antimicrobial properties of silver nanoparticles (AgNPs) are well known thus they are a trend for biomedical applications. The aim of this study was to investigate the antibacterial and antifungal activity of leather coated with AgNPs against two bacteria species Pseudomonas mendocina and Pseudomonas syringae, and the fungi Trichophyton mentagrophytes responsible for foot infections. Porcine leather was cut off and sprinkled with solutions containing various concentrations of metallic AgNPs. Inductively coupled plasma-atomic emission spectrometry (ICP-AES) and texture analysis of the leather were performed to quantify the silver metallic concentration metallic silver and to test the effect of AgNPs on leather softness. Antimicrobial activity was measured by agar diffusion test for zon...
Mishra/Application, 2014
Je voudrais tout d'abord remercier mes directeurs de thèse, François VERDIER et Benoit MIRAMOND d... more Je voudrais tout d'abord remercier mes directeurs de thèse, François VERDIER et Benoit MIRAMOND dont les conseils et les remarques m'ontété utiles pour menerà bien ce projet. Merciégalement aux membres du jury qui m'ont fait l'honneur d'évaluer mon travail, Guy GOGNIAT et Daniel CHILLET qui ont accepté d'enêtre les rapporteurs, Samy MEFTALI et Bertrand GRANADO qui en ontété les examinateurs. Je tiensà remercier Lounis KESSAL et Mahmoud KARABERNOU pour leur soutien et leur bonne humeur tout au long de ces années. Je tiens en particulierà remercier mes collègues de bureau, Laurent GANTEL, qui a toujoursété là pour m'encourager et avec qui j'ai passé d'excellents moments. Je le remercie aussi bien pour son soutien moral que pour son apport scientifique, pour sa disponibilité et son amitié. Un grand mercià Liang Zhou, qui est une femme remarquable, mère et thésardeà la fois. Merciégalementà Lounis Zerioul pour sa présence et ses encouragements, Mohemmed HAMIA, Guy WASSI, et Christian GAMON, qui ont aussí eté très présents et qui sont devenus au fil du temps de véritables amis. Une part de ces remerciements va aux membres du projet FOSFOR avec lesquels j'ai travaillé régulièrement : Fabrice MULLER, Daniel CHILLET, Sébastien PILLEMENT, Lounis KESSAL et Nicolas KNECHT. Enfin je souhaite exprimer toute ma gratitude envers mes parents sans lesquels je n'en serais pas là aujourd'hui, mon oncle Rachid, ma grand-mère MAMIE, mes frères et soeurs, mes amis : Wafaé, Dahlia, Habiba, Imene, Amina, Youcef et tous mes proches pour leur présence et leur soutien durant toutes ces années.
Journal of Nanoscience and Nanotechnology, 2011
Supporting silver and gold on mordenites by ion-exchange method with further reduction with H2 le... more Supporting silver and gold on mordenites by ion-exchange method with further reduction with H2 leads to formation of neutral and charged metal clusters inside zeolite channels as well as metal nanoparticles on external surface of mordenite. A portion of the cluster states of the metals and stability of the clusters depend strongly on acidity of zeolite (determined by SiO2/Al2O3 molar ratio) and nature of zeolite cation (H+, Na+, NH4+). The investigations of silver and gold samples after prolonged storage for 6 and 12 months revealed that silver clusters are comparatively stable while oxidation of gold clusters and nanoparticles by air is the probable cause of deactivation of gold catalysts. The comparison of the results for Au and Ag samples allow suggesting NaM15 and NaM24 mordenites for effective synthesis of complex Au-Ag clusters as active and stable species of catalytic reactions occurring at room temperature.
Applied Catalysis A: General, 2011