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Zhang W, Qian L, He B, Gong X, Zhang G. Mechanism Insights of Antibacterial Surfaces Coated with Dead Probiotics. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023; 39:17632-17643. [PMID: 38033279 DOI: 10.1021/acs.langmuir.3c01818] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/02/2023]
Abstract
To understand the antimicrobial effect of surfaces fabricated with dead probiotics, we prepared surfaces decorated with dead probiotics Lactobacillus rhamnosus GG (LGG) with varied inactivation methods and explored their inhibitory interactions with Pseudomonas aeruginosa (PAO1). By combining several techniques, i.e., digital holographic microscopy (DHM), atomic force microscopy (AFM), RNA sequencing, and metabolomic analysis, we studied the three-dimensional (3D) swimming behaviors, surface adhesion, biofilm formation, and adaptive responses of PAO1 near such surfaces. The results show that planktonic PAO1 decreases their flick and reverse motions by downregulating the chemotaxis pathway and accelerates with less accumulation near dead LGG surfaces by upregulating the flagellar assembly pathway and decreasing cyclic adenosine monophosphate. Distinct from live siblings, the surfaces decorated with dead LGG show a significant reduction in adhesion strength with PAO1 and inhibit biofilm formation with more downregulated genes in the Pseudomonas quinolone signal and biofilm formation pathway. We demonstrate that the antibacterial ability of such surfaces stems from the gradually released lysate from the dead LGG that is unfavorable to PAO1 in close proximity. The releasing rate and order depend on the cell membrane integrity, which closely relates to the inactivation methods.
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Affiliation(s)
- Weixiong Zhang
- Faculty of Materials Science and Engineering, South China University of Technology, Guangzhou 510640, P. R. China
| | - Lu Qian
- Faculty of Materials Science and Engineering, South China University of Technology, Guangzhou 510640, P. R. China
| | - Bingen He
- Faculty of Materials Science and Engineering, South China University of Technology, Guangzhou 510640, P. R. China
| | - Xiangjun Gong
- Faculty of Materials Science and Engineering, South China University of Technology, Guangzhou 510640, P. R. China
- Guangdong Provincial Key Laboratory of Luminescence from Molecular Aggregates, South China University of Technology, Guangzhou 510640, P. R. China
| | - Guangzhao Zhang
- Faculty of Materials Science and Engineering, South China University of Technology, Guangzhou 510640, P. R. China
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Boutonnet C, Lyonnais S, Alpha-Bazin B, Armengaud J, Château A, Duport C. Dynamic Profile of S-Layer Proteins Controls Surface Properties of Emetic Bacillus cereus AH187 Strain. Front Microbiol 2022; 13:937862. [PMID: 35847057 PMCID: PMC9277125 DOI: 10.3389/fmicb.2022.937862] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2022] [Accepted: 06/10/2022] [Indexed: 11/13/2022] Open
Abstract
Many prokaryotes are covered by a two-dimensional array of proteinaceous subunits. This surface layers (S-layer) is incompletely characterized for many microorganisms. Here, we studied Bacillus cereus AH187. A genome analysis identified two genes encoding the S-layer proteins SL2 and EA1, which we experimentally confirmed to encode the two protein components of the S-layer covering the surface of B. cereus. Shotgun proteomics analysis indicated that SL2 is the major component of the B. cereus S-layer at the beginning of exponential growth, whereas EA1 becomes more abundant than SL2 during later stages of stationary growth. Microscopy analysis revealed the spatial organization of SL2 and EA1 at the surface of B. cereus to depend on their temporal-dynamics during growth. Our results also show that a mutant strain lacking functional SL2 and EA1 proteins has distinct surface properties compared to its parental strain, in terms of stiffness and hydrophilicity during the stationary growth phase. Surface properties, self-aggregation capacity, and bacterial adhesion were observed to correlate. We conclude that the dynamics of SL2 and EA1 expression is a key determinant of the surface properties of B. cereus AH187, and that the S-layer could contribute to B. cereus survival in starvation conditions.
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Affiliation(s)
| | | | - Beatrice Alpha-Bazin
- Département Médicaments et Technologies pour la Santé (DMTS), Université Paris Saclay, CEA, INRAE, Bagnols-sur-Cèze, France
| | - Jean Armengaud
- Département Médicaments et Technologies pour la Santé (DMTS), Université Paris Saclay, CEA, INRAE, Bagnols-sur-Cèze, France
| | - Alice Château
- Avignon Université, INRAE, UMR SQPOV, Avignon, France
| | - Catherine Duport
- Avignon Université, INRAE, UMR SQPOV, Avignon, France
- *Correspondence: Catherine Duport,
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Doll PW, Doll K, Winkel A, Thelen R, Ahrens R, Stiesch M, Guber AE. Influence of the Available Surface Area and Cell Elasticity on Bacterial Adhesion Forces on Highly Ordered Silicon Nanopillars. ACS OMEGA 2022; 7:17620-17631. [PMID: 35664577 PMCID: PMC9161423 DOI: 10.1021/acsomega.2c00356] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/18/2022] [Accepted: 03/31/2022] [Indexed: 06/15/2023]
Abstract
Initial bacterial adhesion to solid surfaces is influenced by a multitude of different factors, e.g., roughness and stiffness, topography on the micro- and nanolevel, as well as chemical composition and wettability. Understanding the specific influences and possible interactive effects of all of these factors individually could lead to guidance on bacterial adhesion and prevention of unfavorable consequences like medically relevant biofilm formation. On this way, the aim of the present study was to identify the specific influence of the available surface area on the adhesion of clinically relevant bacterial strains with different membrane properties: Gram-positive Staphylococcus aureus and Gram-negative Aggregatibacter actinomycetemcomitans. As model surfaces, silicon nanopillar specimens with different spacings were fabricated using electron beam lithography and cryo-based reactive ion etching techniques. Characterization by scanning electron microscopy and contact angle measurement revealed almost defect-free highly ordered nanotopographies only varying in the available surface area. Bacterial adhesion forces to these specimens were quantified by means of single-cell force spectroscopy exploiting an atomic force microscope connected to a microfluidic setup (FluidFM). The nanotopographical features reduced bacterial adhesion strength by reducing the available surface area. In addition, the strain-specific interaction in detail depended on the bacterial cell's elasticity and deformability as well. Analyzed by confocal laser scanning microscopy, the obtained results on bacterial adhesion forces could be linked to the subsequent biofilm formation on the different topographies. By combining two cutting-edge technologies, it could be demonstrated that the overall bacterial adhesion strength is influenced by both the simple physical interaction with the underlying nanotopography and its available surface area as well as the deformability of the cell.
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Affiliation(s)
- Patrick W. Doll
- Institute
of Microstructure Technology (IMT), Karlsruhe
Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
| | - Katharina Doll
- Department
of Prosthetic Dentistry and Biomedical Materials Science, Hannover Medical School, Carl-Neuberg-Str. 1, 30625 Hannover, Germany
- Lower
Saxony Centre for Biomedical Engineering, Implant Research and Development (NIFE), Stadtfelddamm 34, 30625 Hannover, Germany
| | - Andreas Winkel
- Department
of Prosthetic Dentistry and Biomedical Materials Science, Hannover Medical School, Carl-Neuberg-Str. 1, 30625 Hannover, Germany
- Lower
Saxony Centre for Biomedical Engineering, Implant Research and Development (NIFE), Stadtfelddamm 34, 30625 Hannover, Germany
| | - Richard Thelen
- Institute
of Microstructure Technology (IMT), Karlsruhe
Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
| | - Ralf Ahrens
- Institute
of Microstructure Technology (IMT), Karlsruhe
Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
| | - Meike Stiesch
- Department
of Prosthetic Dentistry and Biomedical Materials Science, Hannover Medical School, Carl-Neuberg-Str. 1, 30625 Hannover, Germany
- Lower
Saxony Centre for Biomedical Engineering, Implant Research and Development (NIFE), Stadtfelddamm 34, 30625 Hannover, Germany
| | - Andreas E. Guber
- Institute
of Microstructure Technology (IMT), Karlsruhe
Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
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Chathoth K, Fostier L, Martin B, Baysse C, Mahé F. A Multi-Skilled Mathematical Model of Bacterial Attachment in Initiation of Biofilms. Microorganisms 2022; 10:microorganisms10040686. [PMID: 35456739 PMCID: PMC9029265 DOI: 10.3390/microorganisms10040686] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2022] [Revised: 03/15/2022] [Accepted: 03/17/2022] [Indexed: 01/25/2023] Open
Abstract
The initial step of biofilm formation is bacteria attachment to biotic or abiotic surfaces and other bacteria through intra or interspecies interactions. Adhesion can be influenced by physicochemical conditions of the environment, such as iron. There is no available mathematical model of bacterial attachment giving realistic initiation rather than random adhesion. We describe a simple stochastic attachment model, from the simplest case in two dimensions with one bacterial species attaching on a homogeneous flat surface to more complex situations, with either several bacterial species, inhomogeneous or non-flat surfaces, or in three dimensions. The model depends on attachment probabilities (on the surface, laterally, or vertically on bacteria). Effects of each of these parameters were analyzed. This mathematical model is then applied to experimental oral microcolonies of Porphyromonas gingivalis, Streptococcus gordonii, and Treponema denticola, either as mono-, two, or three species, under different iron concentrations. The model allows to characterize the adhesion of three bacterial species and explore the effect of iron on attachment. This model appears as a powerful tool for initial attachment analysis of bacterial species. It will enable further modeling of biofilm formation in later steps with biofilm initialization more relevant to real-life subgingival biofilms.
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Affiliation(s)
- Kanchana Chathoth
- CIMIAD, NUMECAN INSERM U1241, Université de Rennes 1, F-35043 Rennes, France; (K.C.); (B.M.); (C.B.)
| | - Louis Fostier
- IRMAR, CNRS UMR 6625, Université de Rennes, F-35000 Rennes, France;
| | - Bénédicte Martin
- CIMIAD, NUMECAN INSERM U1241, Université de Rennes 1, F-35043 Rennes, France; (K.C.); (B.M.); (C.B.)
| | - Christine Baysse
- CIMIAD, NUMECAN INSERM U1241, Université de Rennes 1, F-35043 Rennes, France; (K.C.); (B.M.); (C.B.)
| | - Fabrice Mahé
- IRMAR, CNRS UMR 6625, Université de Rennes, F-35000 Rennes, France;
- Correspondence:
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Zeng W, Li P, Huang Y, Xia A, Zhu X, Zhu X, Liao Q. How Interfacial Properties Affect Adhesion: An Analysis from the Interactions between Microalgal Cells and Solid Substrates. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:3284-3296. [PMID: 35231169 DOI: 10.1021/acs.langmuir.2c00042] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Microalgal biofilm, a stable community of many algal cells attached to a solid substrate, plays a significant role in the efficient accumulation of renewable energy feedstocks, wastewater treatment, and carbon reduction. The adhesion tendency of microalgal cells on solid substrates is the basis for controlling the formation and development of microalgal biofilm. To promote the adhesion of microalgal cells on solid substrates, it is necessary to clarify which surface properties have to be changed in the most critical factors affecting the adhesion. However, there have been few systematic discussions on what surface properties influence the adhesion tendency of algal cells on solid substrates. In this study, the essential principle of microalgal cell adhesion onto solid substrates was explored from the perspective of the interaction energy between microalgal cells and solid substrates. The influence of surface properties between microalgal cells and solid substrates on interaction energies was discussed via extended Derjaguin-Landau-Verwey-Overbeek (eDLVO) theory and a sensitivity analysis. The results showed that surface properties, including surface potential (ξ) and surface free energy components, significantly affect the adhesion tendency of microalgal cells on different solid substrates. When the solid surface possesses positive charges (ξ > 0), reducing ξ or the electron donor components of the solid substrate (γs-) is an effective measure to promote microalgal cell adhesion onto the solid substrate. When the solid surface possesses negative charges (ξ < 0), an increase in either γs- or the absolute value of ξ should be avoided in the process of microalgae adhesion. Overall, this research provides a direction for the selection of solid substrates and a direction for surface modification to facilitate the adhesion tendency of microalgal cells on solid substrates under different scenarios.
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Affiliation(s)
- Weida Zeng
- Key Laboratory of Low-Grade Energy Utilization Technologies and Systems, Chongqing University, Ministry of Education, Chongqing 400044, China
- Institute of Engineering Thermophysics, School of Energy and Power Engineering, Chongqing University, Chongqing 400044, China
| | - Peirong Li
- Key Laboratory of Low-Grade Energy Utilization Technologies and Systems, Chongqing University, Ministry of Education, Chongqing 400044, China
- Institute of Engineering Thermophysics, School of Energy and Power Engineering, Chongqing University, Chongqing 400044, China
| | - Yun Huang
- Key Laboratory of Low-Grade Energy Utilization Technologies and Systems, Chongqing University, Ministry of Education, Chongqing 400044, China
- Institute of Engineering Thermophysics, School of Energy and Power Engineering, Chongqing University, Chongqing 400044, China
| | - Ao Xia
- Key Laboratory of Low-Grade Energy Utilization Technologies and Systems, Chongqing University, Ministry of Education, Chongqing 400044, China
- Institute of Engineering Thermophysics, School of Energy and Power Engineering, Chongqing University, Chongqing 400044, China
| | - Xianqing Zhu
- Key Laboratory of Low-Grade Energy Utilization Technologies and Systems, Chongqing University, Ministry of Education, Chongqing 400044, China
- Institute of Engineering Thermophysics, School of Energy and Power Engineering, Chongqing University, Chongqing 400044, China
| | - Xun Zhu
- Key Laboratory of Low-Grade Energy Utilization Technologies and Systems, Chongqing University, Ministry of Education, Chongqing 400044, China
- Institute of Engineering Thermophysics, School of Energy and Power Engineering, Chongqing University, Chongqing 400044, China
| | - Qiang Liao
- Key Laboratory of Low-Grade Energy Utilization Technologies and Systems, Chongqing University, Ministry of Education, Chongqing 400044, China
- Institute of Engineering Thermophysics, School of Energy and Power Engineering, Chongqing University, Chongqing 400044, China
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Kuyukina MS, Glebov GG, Ivshina IB. Effects of Nickel Nanoparticles on Rhodococcus Cell Surface Morphology and Nanomechanical Properties. NANOMATERIALS 2022; 12:nano12060951. [PMID: 35335763 PMCID: PMC8955278 DOI: 10.3390/nano12060951] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/22/2022] [Revised: 03/09/2022] [Accepted: 03/11/2022] [Indexed: 12/10/2022]
Abstract
Nickel nanoparticles (NPs) are used for soil remediation and wastewater treatment due to their high adsorption capacity against complex organic pollutants. However, despite the growing use of nickel NPs, their toxicological towards environmental bacteria have not been sufficiently studied. Actinobacteria of the genus Rhodococcus are valuable bioremediation agents degrading a range of harmful and recalcitrant chemicals. Both positive and negative effects of metal ions and NPs on the biodegradation of organic pollutants by Rhodococcus were revealed, however, the mechanisms of such interactions, in addition to direct toxic effects, remain unclear. In the present work, the influence of nickel NPs on the viability, surface topology and nanomechanical properties of Rhodococcus cells have been studied. Bacterial adaptations to high (up to 1.0 g/L) concentrations of nickel NPs during prolonged (24 and 48 h) exposure were detected using combined confocal laser scanning and atomic force microscopy. Incubation with nickel NPs resulted in a 1.25–1.5-fold increase in the relative surface area and roughness, changes in cellular charge and adhesion characteristics, as well as a 2–8-fold decrease in the Young’s modulus of Rhodococcus ruber IEGM 231 cells. Presumably, the treatment of rhodococcal cells with sublethal concentrations (0.01–0.1 g/L) of nickel NPs facilitates the colonization of surfaces, which is important in the production of immobilized biocatalysts based on whole bacterial cells adsorbed on solid carriers. Based on the data obtained, cell surface functionalizing with NPs is possible to enhance adhesive and catalytic properties of bacteria suitable for environmental applications.
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Affiliation(s)
- Maria S. Kuyukina
- Microbiology and Immunology Department, Perm State University, 614990 Perm, Russia; (G.G.G.); (I.B.I.)
- Institute of Ecology and Genetics of Microorganisms, Perm Federal Research Center, Russian Academy of Sciences, 614081 Perm, Russia
- Correspondence:
| | - Grigorii G. Glebov
- Microbiology and Immunology Department, Perm State University, 614990 Perm, Russia; (G.G.G.); (I.B.I.)
- Institute of Ecology and Genetics of Microorganisms, Perm Federal Research Center, Russian Academy of Sciences, 614081 Perm, Russia
| | - Irena B. Ivshina
- Microbiology and Immunology Department, Perm State University, 614990 Perm, Russia; (G.G.G.); (I.B.I.)
- Institute of Ecology and Genetics of Microorganisms, Perm Federal Research Center, Russian Academy of Sciences, 614081 Perm, Russia
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Galstyan A, Majiya H, Dobrindt U. Regulation of photo triggered cytotoxicity in electrospun nanomaterials: role of photosensitizer binding mode and polymer identity. NANOSCALE ADVANCES 2021; 4:200-210. [PMID: 36132947 PMCID: PMC9418932 DOI: 10.1039/d1na00717c] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/27/2021] [Accepted: 11/08/2021] [Indexed: 06/16/2023]
Abstract
Although electrospun nanomaterials containing photoactive dyes currently compete with the present state of art antimicrobial materials, relatively few structure-activity relationships have been established to identify the role of carrier polymer and photosensitizer binding mode on the performance of the materials. In this study scaffolds composed of poly(vinyl alcohol), polyacrylonitrile, poly(caprolactone), and tailor-made phthalocyanine-based photosensitizers are developed utilizing electrospinning as a simple, time and cost-effective method. The photoinduced activity of nanofibrous materials was characterized in vitro against E. coli and B. subtilis as models for Gram-negative and Gram-positive bacteria respectively, as well as against bacteriophages phi6 and MS2 as models for enveloped and non-enveloped viruses respectively. For the first time, we show how polymer-specific properties affect antifouling and antimicrobial activity of the nanofibrous material, indicating that the most promising way to increase efficiency is likely via methods that focus on increasing the number of short, but strong and reversible bacteria-surface interactions.
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Affiliation(s)
- Anzhela Galstyan
- Center for Soft Nanoscience Westfälische Wilhelms-Universität Münster Busso-Peus-Strasse 10 48149 Münster Germany
| | - Hussaini Majiya
- Department of Microbiology, Ibrahim Badamasi Babangida University KM3 Lapai-Minna Road, P.M.B 11 Lapai Nigeria
| | - Urlich Dobrindt
- Institut of Hygiene, Westfälische Wilhelms-Universität Münster Mendelstrasse 7 48149 Münster Germany
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Tamayo L, Santana P, Forero JC, Leal M, González N, Díaz M, Guiliani N, Hamm E, Urzúa M. Coaxial fibers of poly(styrene-co-maleic anhydride)@poly(vinyl alcohol) for wound dressing applications: Dual and sustained delivery of bioactive agents promoting fibroblast proliferation with reduced cell adherence. Int J Pharm 2021; 611:121292. [PMID: 34780927 DOI: 10.1016/j.ijpharm.2021.121292] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Revised: 11/08/2021] [Accepted: 11/09/2021] [Indexed: 11/19/2022]
Abstract
The prevalence of chronic and acute wounds, as well as the complexity of their treatment represent a great challenge for health systems around the world. In this context, the development of bioactive wound dressings that release active agents to prevent infections and promote wound healing, appears as the most promising solution. In this work, we develop an antibacterial and biocompatible wound dressing material made from coaxial electrospun fibers of poly(styrene-co-maleic anhydride) and poly(vinyl alcohol) (PSMA@PVA). The coaxial configuration of the fibers consists of a shell of poly (styrene-co-maleic anhydride) containing a variable concentration of silver nanoparticles (AgNPs) 0.1-0.6 wt% as antibacterial agent, and a core of PVA containing 1 wt% allantoin as healing agent. The fibers present diameters between 0.72 and 1.7 µm. The release of Ag+ in a physiological medium was studied for 72 h, observing a burst release during the first 14 h and then a sustained and controlled release during the remaining 58 h. Allantoin release curves showed significant release only after 14 h. The meshes showed an antibacterial activity against Pseudomonas aeruginosa and Bacillus subtilis that correlates with the amount of AgNPs incorporated and the release rate of Ag+. Indeed, meshes containing 0.3 and 0.6 wt% of AgNPs showed a 99.99% inhibition against both bacteria. The adherence and cell viability of the meshes were evaluated in mouse embryonic fibroblasts NIH/3T3, observing a significant increase in cell viability after 72 h of incubation accompanied by a reduced adhesion of fibroblasts that decreased in the presence of the active agents. These results show that the material prepared here is capable of significantly promoting fibroblast cell proliferation but without strong adherence, which makes it an ideal material for wound dressings with non-adherent characteristics and with potential for wound healing.
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Affiliation(s)
- Laura Tamayo
- Departamento de Química, Facultad de Ciencias, Universidad de Chile, Las Palmeras 3425, Santiago, Chile
| | - Paula Santana
- Instituto de Ciencias Químicas Aplicadas, Facultad de Ingeniería, Universidad Autónoma de Chile, El Llano Subercaseaux 2801, San Miguel, Santiago 8910060, Chile
| | - Juan C Forero
- Laboratorio de Química Biológica, Instituto de Química, Facultad de Ciencias, Pontificia Universidad Católica de Valparaíso, 2340000, Chile
| | - Matías Leal
- Departamento de Química, Facultad de Ciencias, Universidad de Chile, Las Palmeras 3425, Santiago, Chile
| | - Nicolás González
- Departamento de Química, Facultad de Ciencias, Universidad de Chile, Las Palmeras 3425, Santiago, Chile
| | - Mauricio Díaz
- Laboratorio de Comunicación Bacteriana, Departamento de Biología, Facultad de Ciencias, Universidad de Chile, P. C. 780-0023, Santiago, Chile
| | - Nicolás Guiliani
- Laboratorio de Comunicación Bacteriana, Departamento de Biología, Facultad de Ciencias, Universidad de Chile, P. C. 780-0023, Santiago, Chile
| | - Eugenio Hamm
- Departamento Física, Facultad de Ciencia, Universidad de Santiago de Chile, av. Ecuador 3493, Estación Central, Santiago, Chile
| | - Marcela Urzúa
- Departamento de Química, Facultad de Ciencias, Universidad de Chile, Las Palmeras 3425, Santiago, Chile
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