Conductive nanostructured materials based on poly-(3,4-ethylenedioxythiophene) (PEDOT) and starch/κ-carrageenan for biomedical applications

Smart electroactive biomaterials are sought to allow the direct delivery of electrical, electrochemical and electromechanical signals to biological tissues. Specifically, poly-(3,4- ethylenedioxythiophene) (PEDOT) is a polymer of special interest attending to its biocompatibility, tuneable electrical conductivity and processing versatility. In this work, nanostructured PEDOT was synthesized using starch/κ-carrageenan aerogels as templates. κ-carrageenan biopolymer acted as doping agent of the conductive polymer to enhance the biocompatibility and the electrical response. The physicochemical, morphological, mechanical and electrical properties of the nanostructured PEDOT and templates were characterized. The incorporation of κ-carrageenan to the nanostructured materials resulted in an increase in the compressive strength of ca. 40% and a decrease in the electrical impedance of one order-of-magnitude. The synergistic combination of the inherent electrical properties of the PEDOT, the advantageous features of κ-carrageenan as doping agent and the porous morphology of the aerogel template resulted in electroactive PEDOT nanostructures with relevant properties for biomedical applicationsConsejo de Galicia [ED431F 2016/010] y [ED431C 2016/008]; Agencia Estatal de Investigación (AEI);Instituto Tecnológico de Costa Rica (ITCR); Nacional Instituto de Aprendizaje (INA) y las Oficinas Tecnológicas de Costa Rica (MICITT y CONICIT). CAG-G. agradece al MINECO por Beca Ramón y Cajal [RYC- 2014-15239]. Los autores desean agradecer al Dr. Teodolito Guillén (Centro de Investigación y Extensión en Materiales, ITCR) por su asistencia durante el taller mecánico pruebas.S

Supercritical CO2 technology for one-pot foaming and sterilization of polymeric scaffolds for bone regeneration

Sterilization is a quite challenging step in the development of novel polymeric scaffolds for regenerative medicine since conventional sterilization techniques may significantly alter their morphological and physicochemical properties. Supercritical (sc) sterilization, i.e. the use of scCO2 as a sterilizing agent, emerges as a promising sterilization method due to the mild operational conditions and excellent penetration capability. In this work, a scCO2 protocol was implemented for the one-pot preparation and sterilization of poly(-caprolactone) (PCL)/poly(lactic-co-glycolic acid) (PLGA) scaffolds. The sterilization conditions were established after screening against both Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli, Pseudomonas aeruginosa) vegetative bacteria and spores of Bacillus stearothermophilus, Bacillus pumilus and Bacillus atrophaeus. The transition from the sterilization conditions (140 bar, 39 °C) to the compressed foaming (60 bar, 26 °C) was performed through controlled depressurization (3.2 bar/min) and CO2 liquid flow. Controlled depressurization/pressurization cycles were subsequently applied. Using this scCO2 technology toolbox, sterile scaffolds of well-controlled pore architecture were obtained. This sterilization procedure successfully achieved not only SAL-6 against well-known resistant bacteria endospores but also improved the scaffold morphologies compared to standard gamma radiation sterilization proceduresThis work was supported by Xunta de Galicia [ED431F 2016/01, ED431C 2020/17], MCIUN [RTI2018-094131-A-I00], MINECO [SAF2017-83118-R], Consellería de Sanidade, Servizo Galego de Saúde, Axencia de Coñecemento e Saúde (ACIS, CT850A-G), Agencia Estatal de Investigación [AEI] and FEDER funds. V. Santos-Rosales acknowledges to Xunta de Galicia (Consellería de Cultura, Educación e Ordenación Universitaria) for a predoctoral research fellowship [ED481A-2018/014]. C.A. García-González acknowledges to MINECO for a Ramón y Cajal Fellowship [RYC2014-15239]S

Pectin Microspheres: Synthesis Methods, Properties, and Their Multidisciplinary Applications

There is great contemporary interest in using cleaner technologies through green chemistry and utilizing biopolymers as raw material. Pectin is found on plant cell walls, and it is commonly extracted from fruit shells, mostly apples or citrus fruits. Pectin has applications in many areas of commercial relevance; for this reason, it is possible to find available information about novel methods to transform pectin and pursuing enhanced features, with the structuring of biopolymer microspheres being highly cited to enhance its activity. The structuring of polymers is a technique that has been growing in recent decades, due to its potential for diverse applications in various fields of science and technology. Several techniques are used for the synthesis of microspheres, such as ionotropic gelation, extrusion, aerosol drying, or emulsions, with the latter being the most commonly used method based on its reproducibility and simplicity. The most cited applications are in drug delivery, especially for the treatment of colon diseases and digestive-tract-related issues. In the industrial field, it is used for protecting encapsulated compounds; moreover, the environmental applications mainly include the bioremediation of toxic substances. However, there are still many possibilities for expanding the use of this biopolymer in the environmental field

Pectin Microspheres: Synthesis Methods, Properties, and Their Multidisciplinary Applications

There is great contemporary interest in using cleaner technologies through green chemistry and utilizing biopolymers as raw material. Pectin is found on plant cell walls, and it is commonly extracted from fruit shells, mostly apples or citrus fruits. Pectin has applications in many areas of commercial relevance; for this reason, it is possible to find available information about novel methods to transform pectin and pursuing enhanced features, with the structuring of biopolymer microspheres being highly cited to enhance its activity. The structuring of polymers is a technique that has been growing in recent decades, due to its potential for diverse applications in various fields of science and technology. Several techniques are used for the synthesis of microspheres, such as ionotropic gelation, extrusion, aerosol drying, or emulsions, with the latter being the most commonly used method based on its reproducibility and simplicity. The most cited applications are in drug delivery, especially for the treatment of colon diseases and digestive-tract-related issues. In the industrial field, it is used for protecting encapsulated compounds; moreover, the environmental applications mainly include the bioremediation of toxic substances. However, there are still many possibilities for expanding the use of this biopolymer in the environmental field

What are the Main Sensor Methods for Quantifying Pesticides in Agricultural Activities? A Review

IRETIn recent years, there has been an increase in pesticide use to improve crop production due to the growth of agricultural activities. Consequently, various pesticides have been present in the environment for an extended period of time. This review presents a general description of recent advances in the development of methods for the quantification of pesticides used in agricultural activities. Current advances focus on improving sensitivity and selectivity through the use of nanomaterials in both sensor assemblies and new biosensors. In this study, we summarize the electrochemical, optical, nano-colorimetric, piezoelectric, chemo-luminescent and fluorescent techniques related to the determination of agricultural pesticides. A brief description of each method and its applications, detection limit, purpose—which is to efficiently determine pesticides—cost and precision are considered. The main crops that are assessed in this study are bananas, although other fruits and vegetables contaminated with pesticides are also mentioned. While many studies have assessed biosensors for the determination of pesticides, the research in this area needs to be expanded to allow for a balance between agricultural activities and environmental protection.En los últimos años, ha habido un aumento en el uso de plaguicidas para mejorar la producción de cultivos debido al crecimiento de las actividades agrícolas. En consecuencia, varios plaguicidas han estado presentes en el medio ambiente durante un período de tiempo prolongado. Esta revisión presenta una descripción general de los avances recientes en el desarrollo de métodos para la cuantificación de plaguicidas utilizados en actividades agrícolas. Los avances actuales se centran en mejorar la sensibilidad y la selectividad mediante el uso de nanomateriales tanto en conjuntos de sensores como en nuevos biosensores. En este estudio resumimos las técnicas electroquímicas, ópticas, nano-colorimétricas, piezoeléctricas, quimioluminiscentes y fluorescentes relacionadas con la determinación de plaguicidas agrícolas. Se considera una breve descripción de cada método y sus aplicaciones, límite de detección, propósito, que es determinar de manera eficiente los pesticidas, el costo y la precisión. Los principales cultivos que se evalúan en este estudio son el banano, aunque también se mencionan otras frutas y verduras contaminadas con plaguicidas. Si bien muchos estudios han evaluado biosensores para la determinación de pesticidas, la investigación en esta área debe ampliarse para permitir un equilibrio entre las actividades agrícolas y la protección del medio ambiente.Instituto Tecnológico de Costa RicaUniversidad Nacional, Costa RicaInstituto Regional de Estudios en Sustancias Tóxica

Toward Thermochromic VO2 Nanoparticles Polymer Films Based Smart Windows Designed for Tropical Climates

Thermochromic smart windows have been extensively investigated due to two main benefits: first, the comfort for people in a room through avoiding high temperatures resulting from solar heating while taking advantage of the visible light, and second, the energy efficiency saving offered by using those systems. Vanadium dioxide (VO2) is one of the most used materials in the development of thermochromic devices. The countries located in the tropics show little use of these technologies, although studies indicate that due to their characteristics of solar illumination and temperature, they could benefit greatly. To optimize and achieve maximum benefit, it is necessary to design a window that adjusts to tropical conditions and at the same time remains affordable for extensive implementation. VO2 nanoparticles embedded in polymeric matrices are an option, but improvements are required by means of studying different particle sizes, dopants and polymeric matrices. The purpose of this review is to analyze what has been regarding toward the fabrication of smart windows based on VO2 embedded in polymeric matrices for tropical areas and provide a proposal for what this device must comply with to contribute to these specific climatic needs

Electrochemical Characterization of Mancozeb Degradation for Wastewater Treatment Using a Sensor Based on Poly (3,4-ethylenedioxythiophene) (PEDOT) Modified with Carbon Nanotubes and Gold Nanoparticles

Mancozeb is a worldwide fungicide used on a large scale in agriculture. The active component and its main metabolite, ethylene thiourea, has been related to health issues. Robust, fast, and reliable methodologies to quantify its presence in water are of great importance for environmental and health reasons. The electrochemical evaluation of mancozeb using a low-cost electrochemical electrode modified with poly (3,4-ethylene dioxythiophene), multi-walled carbon nanotubes, and gold nanoparticles is a novel strategy to provide an in-situ response for water pollution from agriculture. Additionally, the thermal-, electrochemical-, and photo-degradation of mancozeb and the production of ethylene thiourea under controlled conditions were evaluated in this research. The mancozeb solutions were characterized by electrochemical oxidation and ultraviolet-visible spectrophotometry, and the ethylene thiourea concentration was measured using ultra-high-performance liquid chromatography high-resolution mass spectrometry. The degradation study of mancozeb may provide routes for treatment in wastewater treatment plants. Therefore, a low-cost electrochemical electrode was fabricated to detect mancozeb in water with a robust electrochemical response in the linear range as well as a quick response at a reduced volume. Hence, our novel modified electrode provides a potential technique to be used in environmental monitoring for pesticide detectionMancozeb es un fungicida mundial que se utiliza a gran escala en la agricultura. El componente activo y su principal metabolito, la etilentiourea, se ha relacionado con problemas de salud. Las metodologías robustas, rápidas y fiables para cuantificar su presencia en el agua son de gran importancia por motivos medioambientales y de salud. La evaluación electroquímica de mancozeb utilizando un electrodo electroquímico de bajo costo modificado con poli (3,4-etilen dioxitiofeno), nanotubos de carbono de paredes múltiples y nanopartículas de oro es una estrategia novedosa para proporcionar una respuesta in situ a la contaminación del agua procedente de la agricultura. Además, en esta investigación se evaluó la degradación térmica, electroquímica y fotoeléctrica de mancozeb y la producción de etileno tiourea en condiciones controladas. Las soluciones de mancozeb se caracterizaron por oxidación electroquímica y espectrofotometría ultravioleta-visible, y la concentración de etileno tiourea se midió mediante cromatografía líquida de ultra alta resolución y espectrometría de masas de alta resolución. El estudio de degradación de mancozeb puede proporcionar rutas para el tratamiento en plantas de tratamiento de aguas residuales. Por lo tanto, se fabricó un electrodo electroquímico de bajo costo para detectar mancozeb en agua con una respuesta electroquímica robusta en el rango lineal, así como una respuesta rápida a un volumen reducido. Por lo tanto, nuestro nuevo electrodo modificado proporciona una técnica potencial para ser utilizada en el monitoreo ambiental para la detección de pesticidas.Instituto Tecnológico de Costa Rica, Costa RicaUniversidad Nacional, Costa RicaUniversidad de Costa Rica, Costa RicaDepartamento de Físic