Anna Kubacka1, David Rojo2, Mario J Muñoz-Batista1,3, Coral Barbas2, Marcos Fernández-García4, Manuel Ferrer5. 1. Institute of Catalysis and Petrochemistry, Consejo Superior de Investigaciones Científicas, c/Marie Curie 2, 28049, Madrid, Spain. 2. Department of Chemistry and Biochemistry, Facultad de Farmacia, Centre for Metabolomics and Bioanalysis (CEMBIO), Universidad San Pablo-CEU, CEU Universities, Urbanización Montepríncipe, 28660 Boadilla del Monte, Madrid, Spain. 3. Department of Chemical Engineering, University of Granada, Av. de La Fuente Nueva S/N, 18071, Granada, Spain. 4. Institute of Catalysis and Petrochemistry, Consejo Superior de Investigaciones Científicas, c/Marie Curie 2, 28049, Madrid, Spain. mfg@icp.csic.es. 5. Institute of Catalysis and Petrochemistry, Consejo Superior de Investigaciones Científicas, c/Marie Curie 2, 28049, Madrid, Spain. mferrer@icp.csic.es.
Abstract
INTRODUCTION: The silver/graphitic carbon nitride (Ag/g-C3N4) composite system exerts biocidal activity against the pathogenic bacterium Escherichia coli 1337-H that is stronger than that of well-known silver and titanium oxide (TiO2)-based composites. However, whether the Ag/g-C3N4 composite system has biocidal properties that the parent components do or do not have as separate chemical entities and whether they differ from those in Ag/TiO2 composite photocatalysts have not been clarified. OBJECTIVE: We investigated the chemical (cooperative charge handling and electronic properties) and biological (metabolic) effects exerted by the addition of Ag to g-C3N4 and to TiO2. METHODS: In this work, we undertook metabolome-wide analysis by liquid chromatography-electrospray ionization-quadrupole-time of flight-mass spectrometry to compare the metabolite profiles of untreated E. coli 1337-H cells or those subjected to disinfection with Ag, g-C3N4, 2Ag/g-C3N4, TiO2 and 2Ag/TiO2. RESULTS: While Ag or g-C3N4 moderately affected microbial metabolism according to the mean of the altered metabolites, multiple cell systems contributing to rapid cell death were immediately affected by the light-triggered radical species produced when Ag and g-C3N4 were as xAg/g-C3N4. The effects include drastically reduced production of small metabolites essential for detoxifying reactive oxygen species and those that regulate DNA replication fidelity, cell morphology and energy status. These biological consequences were different from those caused by Ag/TiO2-based biocides, demonstrating the uniqueness of the Ag/g-C3N4 system. CONCLUSIONS: Our results support the idea that the unique Ag/g-C3N4 biocidal properties are based on synergistic action and reveal new directions for designing future photocatalysts for use in disinfection and microbial control.
INTRODUCTION: The silver/graphitic carbon nitride (Ag/g-C3N4) composite system exerts biocidal activity against the pathogenic bacterium Escherichia coli 1337-H that is stronger than that of well-known silver and titanium oxide (TiO2)-based composites. However, whether the Ag/g-C3N4 composite system has biocidal properties that the parent components do or do not have as separate chemical entities and whether they differ from those in Ag/TiO2 composite photocatalysts have not been clarified. OBJECTIVE: We investigated the chemical (cooperative charge handling and electronic properties) and biological (metabolic) effects exerted by the addition of Ag to g-C3N4 and to TiO2. METHODS: In this work, we undertook metabolome-wide analysis by liquid chromatography-electrospray ionization-quadrupole-time of flight-mass spectrometry to compare the metabolite profiles of untreated E. coli 1337-H cells or those subjected to disinfection with Ag, g-C3N4, 2Ag/g-C3N4, TiO2 and 2Ag/TiO2. RESULTS: While Ag or g-C3N4 moderately affected microbial metabolism according to the mean of the altered metabolites, multiple cell systems contributing to rapid cell death were immediately affected by the light-triggered radical species produced when Ag and g-C3N4 were as xAg/g-C3N4. The effects include drastically reduced production of small metabolites essential for detoxifying reactive oxygen species and those that regulate DNA replication fidelity, cell morphology and energy status. These biological consequences were different from those caused by Ag/TiO2-based biocides, demonstrating the uniqueness of the Ag/g-C3N4 system. CONCLUSIONS: Our results support the idea that the unique Ag/g-C3N4 biocidal properties are based on synergistic action and reveal new directions for designing future photocatalysts for use in disinfection and microbial control.
Authors: Anna Kubacka; María Suárez Diez; David Rojo; Rafael Bargiela; Sergio Ciordia; Inés Zapico; Juan P Albar; Coral Barbas; Vitor A P Martins dos Santos; Marcos Fernández-García; Manuel Ferrer Journal: Sci Rep Date: 2014-02-19 Impact factor: 4.379