Examinando por Autor "Soto Rifo, Ricardo"

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    Bacterial synthesis of ternary cdsag quantum dots through cation exchange: Tuning the composition and properties of biological nanoparticles for bioimaging and photovoltaic applications
    (MDPI, 2020-04) Órdenes Aenishanslins, Nicolás; Anziani Ostuni, Giovanna; Monrás, Juan Pablo; Tello, Alejandra; Bravo, Denisse; Toro Ascuy, Daniela; Soto Rifo, Ricardo; Prasad, Paras N.; Pérez Donoso, José Manuel
    In this study, we introduce a biological method for the production of ternary Quantum Dots (QDs): complex nanostructures with tunable optical and structural properties that utilizes post-synthesis modifications through cation exchange. This versatile in-situ cation exchange method being reported for the first time shows great potential for extending the scope of microbial synthesis. By using this bacterial-based method, we easily synthesize and purify CdS, CdSAg, and Ag2 S nanocrystals of a size below 15 nm and with variable morphologies that exhibit fluorescence emissions covering a broad spectral range (from 400 to 800 nm). Energy-dispersive X-ray spectroscopy (EDS) results indicate the partial replacement of Cd2+ by Ag+ when AgNO3 concentration is increased. This replacement produces CdSAg ternary QDs hetero-structures with high stability, fluorescence in the NIR-I (700-800 nm), and 36.13% quantum yield. Furthermore, this reaction can be extended for the production of soluble Ag2 S nanoparticles (NPs) without any traces of Cd. QDs biosynthesized through this cation exchange process display very low toxicity when tested in bacterial or human cell lines. Biosynthesized ternary hetero-structures were used as red fluorescent dyes to label HeLa cells in confocal microscopy studies, which validates its use in bioimaging applications in the near infrared region. In addition, the application of biologically-produced cadmium NPs in solar cells is reported for the first time. The three biosynthesized QDs were successfully used as photosensitizers, where the CdSAg QDs show the best photovoltaic parameters. Altogether, obtained results validate the use of bacterial cells for the controlled production of nanomaterials with properties that allow their application in diverse technologies. We developed a simple biological process for obtaining tunable Quantum Dots (QDs) with different metal compositions through a cation exchange process. Nanoparticles (NPs) are produced in the extracellular space of bacterial cells exposed to cysteine and CdCl2 in a reaction that depends on S2− generation mediated by cysteine desulfhydrase enzymes and uses cellular biomolecules to stabilize the nanoparticle. Using this extracellular approach, water-soluble fluorescent CdS, CdSAg, and Ag2 S Quantum Dots with a tunable emission ranging from 400 to 800 nm were generated. This is the first study reporting the use of microorganisms to produce tunable ternary QDs and the first time that a cation exchange process mediated by cells is described. Obtained results validate the use of biological synthesis to produce NPs with new characteristics and opens a completely new research field related to the use of microorganisms to synthesize complex NPs that are difficult to obtain with regular chemical methods. © 2020 by the authors. Licensee MDPI, Basel, Switzerland.
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    Ítem
    Inactivated Vaccine-Induced SARS-CoV-2 Variant-Specific Immunity in Children
    (American Society for Microbiology, 2022-12) Soto, Jorge A.; Melo González, Felipe; Gutierrez Vera, Cristián; Schultz, Bárbara M.; Berríos Rojas, Roslye V.; Rivera Pérez, Daniela; Piña Iturbe, Alejandro; Hoppe Elsholz, Guillermo; Duarte, Luisa F.; Vázquez, Yaneisi; Moreno Tapia, Daniela; Ríos, Mariana; Palacios, Pablo A.; Garcia Betancourt, Richard; Santibañez, Álvaro; Pacheco, Gaspar A.; Mendez, Constanza; Andrade, Catalina A.; Silva, Pedro H.; Diethelm Varela, Benjamín; Astudillo, Patricio; Calvo, Mario; Cárdenas, Antonio; González, Marcela; Goldsack, Macarena; Gutiérrez, Valentina; Potin, Marcela; Schilling, Andrea; Tapia, Lorena I.; Twele, Loreto; Villena, Rodolfo; Grifoni, Albar; Sette, Alessandro; Weiskopf, Daniela; Fasce, Rodrigo A.; Fernández, Jorge; Mora, Judith; Ramírez, Eugenio; Gaete Argel, Aracelly; Acevedo, Mónica L.; Valiente Echeverría, Fernando; Soto Rifo, Ricardo; Retamal Díaz, Angello; Muñoz Jofré, Nathalia; Meng, Xing; Xin, Qianqian; Alarcón Bustamante, Eduardo; González Aramundiz, José V.; Le Corre, Nicole; Álvarez Figueroa, María Javiera; González, Pablo A.; Abarca, Katia; Perret, Cecilia; Carreño, Leandro J.; Bueno, Susan M.; Kalergis, Alexis M.
    Multiple vaccines against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) have been evaluated in clinical trials. However, trials addressing the immune response in the pediatric population are scarce. The inactivated vaccine CoronaVac has been shown to be safe and immunogenic in a phase 1/2 clinical trial in a pediatric cohort in China. Here, we report interim safety and immunogenicity results of a phase 3 clinical trial for CoronaVac in healthy children and adolescents in Chile. Participants 3 to 17 years old received two doses of CoronaVac in a 4-week interval until 31 December 2021. Local and systemic adverse reactions were registered for volunteers who received one or two doses of CoronaVac. Whole-blood samples were collected from a subgroup of 148 participants for humoral and cellular immunity analyses. The main adverse reaction reported after the first and second doses was pain at the injection site. Four weeks after the second dose, an increase in neutralizing antibody titer was observed in subjects relative to their baseline visit. Similar results were found for activation of specific CD41 T cells. Neutralizing antibodies were identified against the Delta and Omicron variants. However, these titers were lower than those for the D614G strain. Importantly, comparable CD41 T cell responses were detected against these variants of concern. Therefore, CoronaVac is safe and immunogenic in subjects 3 to 17 years old, inducing neutralizing antibody secretion and activating CD41 T cells against SARS-CoV-2 and its variants. (This study has been registered at ClinicalTrials .gov under no. NCT04992260.) IMPORTANCE This work evaluated the immune response induced by two doses of CoronaVac separated by 4 weeks in healthy children and adolescents in Chile. To date, few studies have described the effects of CoronaVac in the pediatric population. Therefore, it is essential to generate knowledge regarding the protection of vaccines in this population. Along these lines, we reported the anti-S humoral response and cellular immune response to several SARS-CoV-2 proteins that have been published and recently studied. Here, we show that a vaccination schedule consisting of two doses separated by 4 weeks induces the secretion of neutralizing antibodies against SARS-CoV-2. Furthermore, CoronaVac induces the activation of CD41 T cells upon stimulation with peptides from the proteome of SARS-CoV-2. These results indicate that, even though the neutralizing antibody response induced by vaccination decreases against the Delta and Omicron variants, the cellular response against these variants is comparable to the response against the ancestral strain D614G, even being significantly higher against Omicron. Copyright © 2022 Soto et al.