Browsing by Author "Yarce, Cristhian J."
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Item Decrease of Antimicrobial Resistance through Polyelectrolyte-Coated Nanoliposomes Loaded with β-Lactam Drug(Pharmaceuticals, 2019) Arévalo, Lina M.; Yarce, Cristhian J.; Oñate-Garzón, José; Salamanca, Constain H.Currently, one of the greatest health challenges worldwide is the resistance to antibiotic drugs, which has led to the pursuit of new alternatives for the recovery of biological activity, where the use of different types of nano-systems has shown an interesting potential. In this study, we evaluated the antibiotic activity of a model drug (ampicillin) encapsulated within coated-nanoliposomes on strains of Staphylococcus aureus with different antibiotic-resistance degrees. Hence, liposomes were elaborated by the ethanol injection method and were coated with a cationic polymer (Eudragit E-100) through the layer-by-layer process. Liposome characterization, such as size, polydispersity, zeta potential, and encapsulation efficiency were determined using dynamic light scattering and ultrafiltration/centrifugation techniques. Although biological activity was evaluated using three ATCC strains of S. aureus corresponding to ATCC 25923 (sensitive), ATCC 29213 (resistant) and ATCC 43300 (very resistant). The results showed changes in size (from ~150 to 220 nm), polydispersity (from 0.20 to 0.45) and zeta potential (from −37 to +45 mV) for the coating process. In contrast, encapsulation efficiency of approximately 70% and an increase in antibiotic activity of 4 and 18 times more on those S. aureus-resistant strains have been observed.Item Decrease of antimicrobial resistance through polyelectrolyte-coated nanoliposomes loaded with β-lactam drug(MDPI AG, 2019-03-01) Arévalo, Lina M.; Yarce, Cristhian J.; Oñate-Garzón, José Fernando; Salamanca, Constain H.Currently, one of the greatest health challenges worldwide is the resistance to antibiotic drugs, which has led to the pursuit of new alternatives for the recovery of biological activity, where the use of different types of nano-systems has shown an interesting potential. In this study, we evaluated the antibiotic activity of a model drug (ampicillin) encapsulated within coated-nanoliposomes on strains of Staphylococcus aureus with different antibiotic-resistance degrees. Hence, liposomes were elaborated by the ethanol injection method and were coated with a cationic polymer (Eudragit E-100) through the layer-by-layer process. Liposome characterization, such as size, polydispersity, zeta potential, and encapsulation efficiency were determined using dynamic light scattering and ultrafiltration/centrifugation techniques. Although biological activity was evaluated using three ATCC strains of S. aureus corresponding to ATCC 25923 (sensitive), ATCC 29213 (resistant) and ATCC 43300 (very resistant). The results showed changes in size (from ~150 to 220 nm), polydispersity (from 0.20 to 0.45) and zeta potential (from −37 to +45 mV) for the coating process. In contrast, encapsulation efficiency of approximately 70% and an increase in antibiotic activity of 4 and 18 times more on those S. aureus-resistant strains have been observed. © 2018 by the authors. Licensee MDPI, Basel, Switzerland.Item Evaluation of the Antimicrobial Activity of Cationic Peptides Loaded in Surface-Modified Nanoliposomes against Foodborne Bacteria(International Journal Of Molecular Sciences, 2019) Cantor, Stefania; Vargas, Lina; Rojas A., Oscar E.; Yarce, Cristhian J.; Salamanca, Constain H.; Oñate-Garzón, JoseBacteria are a common group of foodborne pathogens presenting public health issues with a large economic burden for the food industry. Our work focused on a solution to this problem by evaluating antibiotic activity against two bacteria (Listeria monocytogenes and Escherichia coli) of relevance in the field of foodstuffs. We used two approaches: (i) structural modification of the antimicrobial peptides and (ii) nano-vehiculisation of the modified peptides into polymer-coated liposomes. To achieve this, two antimicrobial peptides, herein named ‘peptide +2′ and ‘peptide +5′ were synthesised using the solid phase method. The physicochemical characterisation of the peptides was carried out using measurements of surface tension and dynamic light scattering. Additionally, nanoliposomes were elaborated by the ethanol injection method and coated with a cationic polymer (Eudragit E-100) through the layer-by-layer process. Liposome characterisation, in terms of size, polydispersity and zeta potential, was undertaken using dynamic light scattering. The results show that the degree of hydrophilic modification in the peptide leads to different characteristics of amphipathicity and subsequently to different physicochemical behaviour. On the other hand, antibacterial activity against both bacteria was slightly altered after modifying peptide sequence. Nonetheless, after the encapsulation of the peptides into polymer-coated nano-liposomes, the antibacterial activity increased approximately 2000-fold against that of L. monocytogenes.Item Evaluation of the antimicrobial activity of cationic peptides loaded in surface-modified nanoliposomes against foodborne bacteria(MDPI AG, 2019-02-05) Cantor, Stefania; Vargas, Lina; Rojas, Oscar E.A.; Yarce, Cristhian J.; Salamanca, Constain H.; Oñate-Garzón, José FernandoBacteria are a common group of foodborne pathogens presenting public health issues with a large economic burden for the food industry. Our work focused on a solution to this problem by evaluating antibiotic activity against two bacteria (Listeria monocytogenes and Escherichia coli) of relevance in the field of foodstuffs. We used two approaches: (i) structural modification of the antimicrobial peptides and (ii) nano-vehiculisation of the modified peptides into polymer-coated liposomes. To achieve this, two antimicrobial peptides, herein named ‘peptide +2′ and ‘peptide +5′ were synthesised using the solid phase method. The physicochemical characterisation of the peptides was carried out using measurements of surface tension and dynamic light scattering. Additionally, nanoliposomes were elaborated by the ethanol injection method and coated with a cationic polymer (Eudragit E-100) through the layer-by-layer process. Liposome characterisation, in terms of size, polydispersity and zeta potential, was undertaken using dynamic light scattering. The results show that the degree of hydrophilic modification in the peptide leads to different characteristics of amphipathicity and subsequently to different physicochemical behaviour. On the other hand, antibacterial activity against both bacteria was slightly altered after modifying peptide sequence. Nonetheless, after the encapsulation of the peptides into polymer-coated nano-liposomes, the antibacterial activity increased approximately 2000-fold against that of L. monocytogenes. © 2019 by the authors. Licensee MDPI, Basel, Switzerland.Item Validación no exhaustiva del método analítico de Walkley–Black, para la determinación de materia orgánica en suelos por espectrofotometría de UV-VIS(Universidad Santiago de cali, 2014-03-26) Yarce, Cristhian J.; E. Castillo, JorgeSe presentan las determinaciones estadísticas y los parámetros evaluados para la validación no exhaustiva del método de cuantificación de materia orgánica [MO] (estimada) propuesto por Walkley- Black, aplicado a muestras de suelos. Esta validación tiene como objetivo, dar a conocer algunas características de la metodología, en términos de su linealidad, precisión, límite de detección [LOD], límite de cuantificación [LOQ] y exactitud; tales parámetros, son evaluados bajo las condiciones ambientales, técnicas, instrumentales y de infraestructura del laboratorio de suelos y tejido foliar del Centro de Investigación de la Caña de Azúcar de Colombia [Cenicaña]. Los resultados obtenidos fueron los siguientes: rango de trabajo lineal entre 0.363 – 5.081% MO, con un coeficiente de determinación r2= 0.9969; precisión expresada como repetibilidad: 0.1411% MO y como reproducibilidad: 0.0446% MO; el límite de detección obtenido fue de 0.064% MO; el límite de cuantificación por su parte fue de 0.2120% MO y por último la exactitud en términos del porcentaje de recuperación al 50% fue de 97%MO y al 100%, se obtuvo el mismo porcentaje.