Browsing by Author "Bollo, Soledad"

Now showing 1 - 9 of 9
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    Effect of the Dispersing Agent on the Electrochemical Response of Glassy Carbon Electrodes Modified with Dispersions of Carbon Nanotubes
    (WILEY-V C H VERLAG GMBH, 2012) Gonzalez Segura, Karina; Canete Rosales, Paulina; del Rio, Rodrigo; Yanez, Claudia; Ferreyra, Nancy F.; Rivas, Gustavo A.; Bollo, Soledad
    The electrochemical response of a glassy carbon electrode modified with carbon nanotubes (CNT) dispersed in two solvents, water and DMF, and two polymers, chitosan and Nafion is reported. The films were homogeneous when the dispersing agent was water or DMF. In the case of polymers, the surfaces present areas with different density of CNTs. A more sensitive electrochemical response was obtained when CNTs are dispersed in the solvents. In the case of CNT dispersed with polymers, the nature of the polymer demonstrated to be a critical parameter not only for dispersing the nanotubes but also for the electrochemical activity of the resulting electrodes.
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    Electrocatalytic activity of nanohybrids based on carbon nanomaterials and MFe2O4 (M=Co, Mn) towards the reduction of hydrogen peroxide
    (2018) Gutierrez, Fabiana A.; Mazario, Eva; Menéndez, Nieves; Herrasti, Pilar; Rubianes, María D.; Zagal, José H.; Yañez, C.; Rivas, Gustavo A.; Bollo, Soledad; Recio Cortés, Francisco Javier
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    Electrocatalytic reduction of nitrite on tetraruthenated metalloporphyrins/Nafion glassy carbon modified electrode
    (2011) Calfuman, Karla; Aguirre, Maria Jesus; Canete-Rosales, Paulina; Bollo, Soledad; Llusar, Rosa; Isaacs Casanova, Mauricio
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    Elimination of sulfamethoxazole by anodic oxidation using mixed metal oxide anodes
    (2023) Lauzurique, Yeney; Miralles-Cuevas, Sara; Godoy, Mariel; Sepulveda, Pamela; Bollo, Soledad; Cabrera-Reina, Alejandro; Huilinir, Cesar; Malato, Sixto; Oller, Isabel; Salazar-Gonzalez, Ricardo
    The degradation of sulfamethoxazole (SMX) was studied by anodic oxidation (AO) process using mixed metal oxide (MMO) electrodes with different Ru/Ir ratios. Each electrode was characterized morphological and electrochemically. The electrolyzes were performed in NaCl and Na2SO4 applying two current densities (10 and 50 mA cm-2). The electrode with the highest composition of Ir, Ru/Ir (30/70), showed greater SMX degradation and generation of oxidizing species and was used to treat the antibiotic by AO and AO assisted by solar energy in natural water and actual municipal wastewater effluents.The efficiency in SMX degradation depends on the type of electrode used (MMO) and electrolytic medium. All MMO electrodes, reached almost total degradation of SMX in chloride medium. However, 60 % degradation of SMX in sulfate medium was achieved with anode with lower Ru/Ir ratio. Additionally, degradation of SMX in complex matrices can be successfully carried out by solar-assisted AO and AO processes, without the need to adjust the pH, at room temperature and using anode with lower Ru/Ir ratio. Finally, the AO process assisted by solar energy reduced electrolysis times and the cell's potential, leading to lower energy consumption.
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    Functionalization of Gold Nanostars with Cationic β-Cyclodextrin-Based Polymer for Drug Co-Loading and SERS Monitoring
    (2021) Donoso-Gonzalez, Orlando; Lodeiro, Lucas; Aliaga, Alvaro E.; Laguna-Bercero, Miguel A.; Bollo, Soledad; Kogan, Marcelo J.; Yutronic, Nicolas; Sierpe, Rodrigo
    Gold nanostars (AuNSs) exhibit modulated plasmon resonance and have a high SERS enhancement factor. However, their low colloidal stability limits their biomedical application as a nanomaterial. Cationic beta-cyclodextrin-based polymer (CCD/P) has low cytotoxicity, can load and transport drugs more efficiently than the corresponding monomeric form, and has an appropriate cationic group to stabilize gold nanoparticles. In this work, we functionalized AuNSs with CCD/P to load phenylethylamine (PhEA) and piperine (PIP) and evaluated SERS-based applications of the products. PhEA and PIP were included in the polymer and used to functionalize AuNSs, forming a new AuNS-CCD/P-PhEA-PIP nanosystem. The system was characterized by UV-VIS, IR, and NMR spectroscopy, TGA, SPR, DLS, zeta potential analysis, FE-SEM, and TEM. Additionally, Raman optical activity, SERS analysis and complementary theoretical studies were used for characterization. Minor adjustments increased the colloidal stability of AuNSs. The loading capacity of the CCD/P with PhEA-PIP was 95 +/- 7%. The physicochemical parameters of the AuNS-CCD/P-PhEA-PIP system, such as size and Z potential, are suitable for potential biomedical applications Raman and SERS studies were used to monitor PhEA and PIP loading and their preferential orientation upon interaction with the surface of AuNSs. This unique nanomaterial could be used for simultaneous drug loading and SERS-based detection.
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    Label-free graphene oxide-based surface plasmon resonance immunosensor for the quantification of galectin-3, a novel cardiac biomarker
    (2018) Primo, Emiliano N.; Kogan, Marcelo J.; Verdejo Pinochet, Hugo; Bollo, Soledad; Rubianes, María D.; Rivas, Gustavo A.
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    Label-Free Oligonucleotide-Based SPR Biosensor for the Detection of the Gene Mutation Causing Prothrombin-Related Thrombophilia
    (2020) Sierpe, Rodrigo; Kogan, Marcelo J.; Bollo, Soledad
    Prothrombin-related thrombophilia is a genetic disorder produced by a substitution of a single DNA base pair, replacing guanine with adenine, and is detected mainly by polymerase chain reaction (PCR). A suitable alternative that could detect the single point mutation without requiring sample amplification is the surface plasmon resonance (SPR) technique. SPR biosensors are of great interest: they offer a platform to monitor biomolecular interactions, are highly selective, and enable rapid analysis in real time. Oligonucleotide-based SPR biosensors can be used to differentiate complementary sequences from partially complementary or noncomplementary strands. In this work, a glass chip covered with an ultrathin (50 nm) gold film was modified with oligonucleotide strands complementary to the mutated or normal (nonmutated) DNA responsible for prothrombin-related thrombophilia, forming two detection platforms called mutated thrombophilia (MT) biosensor and normal thrombophilia (NT) biosensor. The results show that the hybridization response is obtained in 30 min, label free and with high reproducibility. The sensitivity obtained in both systems was approximately 4 Delta mu RIU/nM. The dissociation constant and limits of detection calculated were 12.2 nM and 20 pM (3 fmol), respectively, for the MT biosensor, and 8.5 nM and 30 pM (4.5 fmol) for the NT biosensor. The two biosensors selectively recognize their complementary strand (mutated or normal) in buffer solution. In addition, each platform can be reused up to 24 times when the surface is regenerated with HCl. This work contributes to the design of the first SPR biosensor for the detection of prothrombin-related thrombophilia based on oligonucleotides with single point mutations, label-free and without the need to apply an amplification method.
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    Nanostructured Fe-N-C pyrolyzed catalyst for the H2O2 electrochemical sensing
    (2021) Candia-Onfray, Christian; Bollo, Soledad; Yanez, Claudia; Escalona, Nestor; Marco, Jose F.; Menendez, Nieves; Salazar, Ricardo; Recio, F. Javier
    Fe-N-C pyrolyzed materials have been proposed as substitutes of the noble-based catalyst for energy conversion reactions. However, their use as electrochemical sensors has not been deeply explored. In the present work, different Fe-N-C pyrolyzed catalysts were synthesized for the amperometric sensing of the H2O2 reduction in neutral media. The catalysts were characterized by BET, TEM, FESEM, XPS, Mossbauer spectroscopy, and cyclic voltammetry. The catalysts present an N-doped graphitic matrix with a macroporous structure and mesoporous contribution. Different amounts of N-pyridinic, N-pyrrolic, N-graphitic, N-oxides, and FeN4 sites have been detected on the catalysts. Among the different active sites present in the catalysts, the FeN4 structure is proposed as the most catalytic active site for the hydrogen peroxide reduction reaction (HPRR). Under optimal conditions (0.61 V vs. NHE, 0.00 V vs. Ag/AgCl), the materials show a lineal amperometric response in the range of 0.08 and 14 mu M, with a sensitivity of 31.3 mu A mu M-1 cm(-2), and a detection and quantification limits of 0.25 mu M and 0.75 mu M respectively. The amperometric results indicate that the best performance is reached when increasing the amount of FeN4 active sites, and the redox potential of the FeN4 species becomes more positive. The Fe-N-C catalyst stands out for the more positive working potential than other materials proposed in the literature. (C) 2021 Elsevier Ltd. All rights reserved.