Sistema Regional de Información
en línea para Revistas Científicas de América Latina,
el Caribe, España y Portugal

Silver nanoparticles (NPs-Ag) are of great interest due to the potential applications in different areas. In order to find methodologies that not represent human health risk and also an ecofriendly one, biosynthesis of these nanoparticles has been a viable option. It is known that diverse biomolecules present in microorganisms can function as an oxidative, reductor and/or stabilizer agents, thanks to that silver nanoparticles synthesis could be favored. In this work the main objectives were the biosynthesis, characterization, and evaluation of antibacterial activity of NPs-Ag. Biosynthesis was made using the culture supernatant of Pseudomonas aeruginosa. The NPs-Ag were characterized using UV-Vis spectroscopy, scanning electron microscopy, X‑ray diffraction and the antimicrobial effect was evaluated by dilution assays in Muller Hinton broth and the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined against Gram-positive and Gram-negative bacteria. A mixture containing 20% of supernatant and 3 mM AgNO3 was the best way to obtain silver nanoparticles. Nanoparticles with mixed morphology were observed. The NPs-Ag showed antibacterial activity over Gram-positive and Gram-negative bacteria with MIC of 1 to 2 µg/ml and MBC of 2 to 4 µg/ml. In conclusion, culture supernatant of P. aeruginosa is a viable pathway for the synthesis of NPs-Ag with antibacterial activity.

Developing biodegradable, compatible, and non-toxic films based on chitosan that allows the incorporation of nanocomposites can be favorable for its application in various industries such as food industry. The objective was to develop films based on a chitosan biopolymer matrix added with silver nanoparticles (AgNPs) and evaluate their physical-mechanical, physicochemical, and microbiological properties for food packaging applications. AgNPs (by the Lee-Meisel method), and chitosan 1% (Q) solutions were synthesized, to evaluate the antimicrobial activity. Films of Q and Q-AgNPs were developed by the casting method and were evaluated by field emission scanning electron microscopy, color assessment, resistance to tension, elongation, elasticity, humidity, solubility, degree of swelling, permeability to water vapor, speed of transmission of water vapor and thickness. The combination of Q-AgNPs showed bacteriostatic effect, while AgNPs showed a delay in the onset of the logarithmic growth phase and decreased growth, compared to control. The Q and Q-AgNPs films were observed homogeneous without porosity. The color of the Q-AgNPs films was slightly more yellow and less luminous, which could confer protection from light. In the same sense, they were less permeable to water vapor which can give them a barrier function, offering a better protective effect for food, in addition, they were 9% more resistant to elongation, which makes them more malleable, under these conditions, it is concluded that Q-AgNPs films are feasible to be applied as coatings or packaging for food. 

Nanotechnology (NT) can modernize agriculture with new tools that allow better nourished and protected crops. Graphene oxide (GO) is a new kind of carbon-based nanomaterial with unique structural and physicochemical properties, which is very useful for many agricultural applications. GO, the two-dimensional carbon nanoparticles, have attracted increasing attention in the last few years because these contain large amounts of functional oxygen groups; therefore, they could be used as a fertilizer carrier to slow the release rate and improve the nutrients use efficiency, which makes this material suitable for developing new slow-release fertilizers. In this study, the application of GO nanoparticles (NPs) and graphite microparticles were compared as potential promoters of tomato seed germination and seedlings growth. Concentrations of 0, 50, 100, 200, and 500 mg L–1 were applied, using distilled water and micro-size graphite as controls. GO treatments improved root growth dose-dependently by increasing the seed vigor and showing significant differences (P ≤ 0.05) between treatments applied, increasing antioxidant enzymes activities. When using the dose of 200 mg L–1 GONPs, the radicle length was stimulated (31%) compared to the control seedlings. The graphite NPs performed better than the control in all variables; however, they were surpassed by the treatments with GONPs.

En el presente estudio exploratorio se analizan las dificultades de los estudiantes del bachillerato para la representación y ubicación de objetos y procesos en nanoescala, así como sus concepciones sobre las nanociencias y nanotecnología en cuanto a sus implicaciones y áreas del conocimiento con las que se relaciona. También se analiza su interés para que este campo se introduzca curricularmente en el bachillerato. Para ello, se construyó un cuestionario que se aplicó en línea a alumnos de bachillerato durante la pandemia de COVID 19 y, posterior a la misma, con los estudiantes ya de forma presencial en la escuela. El cuestionario incorpora algunas preguntas de investigaciones previas y otras nuevas. Los resultados detallan los rangos de escala en la que los estudiantes presentan mayores dificultades, tanto en la determinación del tamaño de objetos como de procesos. También se encontró que, en su mayoría, generalizan las leyes físicas a toda escala. Se muestra que los alumnos tienen clara la importancia de las nanociencias y la nanotecnología en el desarrollo científico y tecnológico, así como para la vida cotidiana, pero no muestran interés porque se incorporen al currículo de ciencias del bachillerato. En el escrito se establecen algunas sugerencias sobre aspectos educativos a considerar para incorporar en este nivel educativo la enseñanza de las nanociencias.

Se presenta el estudio del efecto de la temperatura en la formación de nanoestructuras luminiscentes (NsL) en el monocristal de KBr:Eu2+. Las muestras se almacenaron durante 16 semanas a 100 y 200 °C para formar la fase de Suzuki (FS) y fase dihaluro (FD), respectivamente, la concentración de impurezas en ambos casos fue ~380 ppm. La formación de nanoestructuras fue estudiada por espectroscopía óptica (EO) y las imágenes fueron obtenidas por microscopía de fuerza atómica (AFM). Los espectros de absorción y emisión reportan cambios importantes en 10 Dq para la FS a 11365.2 cm–1, con pico de misión a 433 nm y para la FD 10 Dq a 5319.3 cm–1 con dos picos de emisión a 428.5 y 450.7 nm, característicos de la fase dihaluro. Las imágenes observadas por AFM muestran que las NsL para la FS van desde 40 a 435 nm de diámetro con alturas de 2 a 120 nm, en contraste con la FD donde hay dispersión de tamaños es desde 20 nm hasta de 500 nm de diámetro, pero con alturas limitadas en el intervalo de 1 a 7 nm. Estos resultados comprueban suposiciones teóricas que, efectivamente, la FD es de tipo laminar, los resultados obtenidos están de acuerdo con la literatura reportada. 

A high concentration of air pollutants is being produced in the world’s metropolitan areas because of the growing number of vehicles, factories, industries, and construction sites, causing severe air quality, public health, and structural deterioration. In recent years, to address these problems, photocatalytic building materials have emerged as a new alternative technology to remedy urban air pollution and maintain the aesthetics and functionality of infrastructures. Large surface areas are exposed to the sun in any infrastructure providing the optimal conditions for applying photocatalytic solutions. The great interest in this technology has encouraged the creation of many intelligent building materials with photocatalytic properties by incorporating TiO2 nanoparticles. A wide variety of products are currently available in the market, such as paints, windows, stucco, pavement, cement, etc. The aim of this study is to make a comprehensive review of the photocatalytic process, its properties, its applications in the construction industry, and the problems and limitations of this technology.

The successful use of nanoparticles (NPs) in various sectors has increased interest and demand to synthesize, explore and study them. The synthesis of NP (as well as its derivatives, reductions, functionalizations, or conjugations), its properties and applications have been analyzed from modern approaches, through various advanced techniques, for multiple applications. The objective of this paper is to highlight the importance of plants as a source of metabolites and extracts, used as origin and means of NP synthesis. Likewise, green synthesis is highlighted as an environmentally friendly method to take advantage of the wide range of possibilities represented by the natural reservoir of Mexican plants and its various applications and properties to be explored in the field of nanobiotechnology.

El presente trabajo tiene la finalidad de dar a conocer el desarrollo de un prototipo de sensor para la medición de mercurio (Hg2+) en solución acuosa sobre una plataforma electroquímica basada en electrodos serigrafiados de nanotubos de carbonos (CNT-SPE) en conjunto con nanopartículas de oro (NPs-Au) realizadas a través de síntesis verde, utilizando extracto acuoso de Sargassum spp. Para esto, se realizó la caracterización de las NPs-Au por espectroscopía ultravioleta-visible (UV-Vis), infrarrojo (TF-IR), difracción de rayos X (DRX) y microscopía electrónica de barrido (SEM); obteniendo nanopartículas entre 80-100 nm las cuales poseen un recubrimiento orgánico que les confiere una sinergia al momento de ser conjugadas con CNT-SPE oxidadas/activadas. Posteriormente, las NPs-Au se utilizaron para modificar el CNT-SPE a través del método drop-casting y así ensamblar un novedoso sensor electroquímico para la medición de Hg2+, cuya validación y habilidad para medir fue demostrada utilizando voltametría diferencial de pulso (DPV). Se obtuvieron límites de detección de 2.38 uM y cuantificación de 3 uM. Los resultados demuestran que la plataforma desarrollada es una alternativa rápida, eficiente y portátil para la medición de Hg2+.

Electrochemical quantification of biomarkers in fluids frequently employs metallic nanoparticles as detection substrates. The development of quantification materials has evolved in recent decades with the incorporation of graphene materials into measurement systems, generating variants of graphene-nanometal composites. Composite materials take advantage of the great electronic conductivity of graphene and the increase in sensitivity and selectivity that it confers. Graphene oxide and its reduced products have traditionally been used in the manufacture of graphene-metal nanoparticle composites. The trend is explained by the relative ease of synthesis of graphene oxidized materials, however, this ease has as a drawback the loss of electrical properties of the synthesized materials and the possible decrease in their detection characteristics. To avoid these restrictions, ideally, non-oxidized graphene materials should be used as substrates, however their manufacture is not easy. This work reports a method of preparing pristine graphene nanoplatelets and their easy conversion to gold nanoparticle-decorated composites. We describe the use of the compounds as useful substrates for the electrochemical quantification of glucose and hydrogen peroxide in fluids.

Plastic waste represents a threat to the environment, not only because of its accumulation and contamination, but also because of the constant degradation it undergoes, leading to its transformation into micro and nanoplastics (MNPLs). The size range of MNPLs makes it easier for them to cross the barriers of organisms, that is, the natural mechanisms that protect the organism from the entry of harmful substances or pathogens, becoming a potential risk factor for human health due to its relatively unknown effects. Human absorption of nanoplastics can occur unintentionally through the food chain through consumption of contaminated food and beverages or possibly through migration of nanoplastic particles from packaging materials to food products, then it is a concern that requires reliable data to assess its safety. In this review, we focus on the literature on research studies in which the effects of MNPLs on colon epithelial cells have been evaluated. These works have evaluated the danger of MNPLs through tests of cell viability, membrane integrity, localization and translocation of MNPs, induction of reactive oxygen species and genotoxic damage to have a comprehensive view of their potentially harmful effects. Most of the plastics produced by the industry are composed of different types of polymers, and given the technological limitation to obtain environmental samples, we work mainly with models of synthesized micro and nanoplastic particles.