Nanopartículas de quitosano: una prometedora estrategia para combatir la resistencia a antimicrobianos

Antimicrobial resistance is a growing global health concern, as many pathogen microorganisms have become resistant to traditional antimicrobial agents. This has led a urging need for the development and research new alternative therapies to combat against this resistant strains. Chitosan nanoparticles have shown to be a promising strategy to overcome this problem, due to their proven antibacterial activity, besides the possibility of carry some antimicrobial agents inside them to enhance the antimicrobial activity. Therefore, this article will summarize briefly the current state on chitosan nanoparticles research to overcome antimicrobial resistance.La resistencia a antimicrobianos es un problema creciente de salud pública mundial, pues cada vez hay más microorganismos patógenos resistentes a los agentes antimicrobianos tradicionales. Esto ha originado una creciente necesidad por investigar y desarrollar nuevas terapias para combatir a estas cepas resistentes. Las nanopartículas de quitosano se han convertido en una alternativa atractiva y prometedora para solucionar este problema, pues ya se ha demostrado su actividad contra bacterias multirresistentes. Además, como sistemas acarreadores de agentes antimicrobianos para liberación controlada, han demostrado ser una alternativa adecuada a la administración convencional de fármacos. Por tanto, en el presente artículo se resumirá brevemente el estado actual de la investigación en nanopartículas de quitosano aplicada en combatir la resistencia a antimicrobianos

Importancia de la nanotecnología en las ciencias veterinarias

Nanotechnology is a discipline that consists of manipulating matter, atom by atom, the materials under study have a scale of less than 100 nm, which can originate naturally or through human intervention by means of a large number of methods and these can acquire different properties depending on the material from which they originate. In veterinary sciences, medicine, livestock production and public health, these technologies represent a historical and innovative advance that allows treating different infectious and degenerative diseases, improving animal breeding and reproduction, as well as monitoring the safety of food of animal origin. However, there is still little research on the subject, so this article aims to provide an overview of the scope and limitations that these new techniques can provide.La nanotecnología es una disciplina que consiste en manipular la materia, átomo por átomo, los materiales de estudio tienen una escala menor a 100 nm, los cuales pueden originarse de manera de forma natural o mediante la intervención del hombre por medio de una gran cantidad de métodos y estos pueden adquirir diferentes propiedades dependiendo de la materia de las que tengan origen. En las ciencias veterinarias, tanto la medicina, como la producción pecuaria, así como la salud pública, estas tecnologías representan un avance histórico e innovador que permite tratar diferentes enfermedades infecciosas y degenerativas, mejorar la crianza y la reproducción de los animales, así como la vigilancia de la inocuidad en los alimentos de origen animal. Sin embargo, aún existe poca investigación al respecto, por lo que este artículo tiene como finalidad brindar un panorama de los alcances y limitaciones que estás nuevas técnicas nos pueden proporciona

Synthesis, characterization and magnetic properties of Co@Au core-shell nanoparticles encapsulated by nitrogen-doped multiwall carbon nanotubes

"Co/Au bilayer thin films were deposited on Si/SiOx substrates using the magnetron sputtering method and used as a catalytic support to grow forests of aligned nitrogen-doped multiwalled carbon nanotubes (N-MWCNT) via chemical vapor deposition (CVD) at 850 °C, using benzylamine (C6H5CH2NH2) as a carbon and nitrogen source. Interestingly, the resulting N-MWCNT contains Co@Au core-shell nanoparticles located at their tips. We found that the metal particle cores consist of cobalt coated by an Au shell of few nanometers. Magnetic measurements revealed a ferromagnetic behavior of the system composed of Co@Au nanoparticles encapsulated inside N-MWCNT. The results are compared with pristine N-MWNT containing only Co nanoparticles encapsulated in their cores.

Síntesis y caraterización de nanoestructuras de carbono: anclaje de nanoparticulas de plata en nanotubos de carbono: teoría y experimento.

Tesis (Doctorado en Nanociencias y Nanotecnología)"En este trabajo se describen tres métodos sencillos y eficientes de anclaje de nanopartículas de plata en la superficie de nanotubos de carbono de pared múltiple dopados con nitrógeno. La importancia de los métodos desarrollados en este trabajo radica en la ausencia de tratamientos agresivos a la superficie de los nanotubos (tratamientos de oxidación). Los diferentes métodos de anclaje incluyen la reducción de las nanopartículas en presencia de los nanotubos. El procedimiento más prometedor se encuentra basado en la mezcla de suspensiones de nanotubos dopados con cúmulos de plata presintetizados. La caracterización de estas muestras incluyó microscopía electrónica de transmisión de alta resolución (HRTEM), microscopía electrónica de barrido (SEM) y difracción de rayos X. Además, se propone un posible mecanismo de anclaje de los cúmulos con la superficie de los tubos dopados, en el cual, la molécula del solvente empleado (Dimetil sulfóxido, DMSO) actúa como eslabón entre la superficie del tubo y los cúmulos de plata. Para entender este mecanismo se realizó un estudio teórico empleando cálculos de primeros principios en el marco de la teoría funcional de la densidad. Los cálculos incluyeron estudios sobre la interacción de diferentes estructuras de carbono con la molécula de DMSO ó con átomos de plata. Finalmente, se presentan resultados sobre la síntesis ycaracterización de nanotubos de pared sencilla y el efecto del dopaje con nitrógeno en estos. La síntesis se llevó acabo usando la técnica de deposición química de vapores. Las muestras obtenidas fueron caracterizadas mediante espectroscopia Raman, HRTEM, SEM y análisis termogravimétrico (TGA).

DFT Study of Adsorption Behavior of Nitro Species on Carbon-Doped Boron Nitride Nanoribbons for Toxic Gas Sensing

The modifications of the electronic properties on carbon-doped boron nitride nanoribbons (BNNRs) as a response to the adsorption of different nitro species were investigated in the framework of the density functional theory within the generalized gradient approximation. Calculations were performed using the SIESTA code. We found that the main response involved tuning the original magnetic behavior to a non-magnetic system when the molecule was chemisorbed on the carbon-doped BNNR. It was also revealed that some species could be dissociated through the adsorption process. Furthermore, the nitro species preferred to interact over nanosurfaces where dopants substituted the B sublattice of the carbon-doped BNNRs. Most importantly, the switch on the magnetic behavior offers the opportunity to apply these systems to fit novel technological applications

Antibacterial Activity of Biosynthesized Selenium Nanoparticles Using Extracts of Calendula officinalis against Potentially Clinical Bacterial Strains

The use of selenium nanoparticles (SeNPs) in the biomedical area has been increasing as an alternative to the growing bacterial resistance to antibiotics. In this research, SeNPs were synthesized by green synthesis using ascorbic acid (AsAc) as a reducing agent and methanolic extract of Calendula officinalis L. flowers as a stabilizer. Characterization of SeNPs was performed by UV-vis spectrophotometry, infrared spectrophotometry (FTIR), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), and transmission electron microscopy (TEM) techniques. SeNPs of 40–60 nm and spherical morphologies were obtained. The antibacterial activity of marigold extracts and fractions was evaluated by disk diffusion methodology. The evaluation of SeNPs at different incubation times was performed through the colony-forming unit (CFU) count, in both cases against Serratia marcescens, Enterobacter cloacae, and Alcaligenes faecalis bacteria. Partial antibacterial activity was observed with methanolic extracts of marigold leaves and flowers and total inhibition with SeNPs from 2 h for S. marcescens, 1 h for E. cloacae, and 30 min for A. faecalis. In addition, SeNPs were found to exhibit antioxidant activity. The results indicate that SeNPs present a potentiated effect of both antimicrobial and antioxidant activity compared to the individual use of marigold extracts or sodium selenite (Na2SeO3). Their application emerges as an alternative for the control of clinical pathogens

Green Synthesis of Gold and Silver Nanoparticles Using Leaf Extract of Capsicum chinense Plant

So far, several studies have focused on the synthesis of metallic nanoparticles making use of extracts from the fruit of the plants from the genus Capsicum. However, as the fruit is the edible, and highly commercial, part of the plant, in this work we focused on the leaves, a part of the plant that is considered agro-industrial waste. The biological synthesis of gold (AuNPs) and silver (AgNPs) nanoparticles using aqueous extracts of root, stem and leaf of Capsicum chinense was evaluated, obtaining the best results with the leaf extract. Gold and silver nanoparticles synthesized using leaf extract (AuNPs-leaf and AgNPs-leaf, respectively) were characterized by UV-visible spectrophotometry (UV-Vis), Fourier Transform Infrared Spectroscopy with Attenuated Total Reflection (FTIR-ATR), X-ray Photoelectron Spectroscopy (XPS), Ultra Hight Resolution Scanning Electron Microscopy coupled to Energy-Dispersive X-ray spectroscopy (UHR-SEM-EDX) and Transmission Electron Microscopy (TEM), and tested for their antioxidant and antimicrobial activities. In addition, different metabolites involved in the synthesis of nanoparticles were analyzed. We found that by the use of extracts derived from the leaf, we could generate stable and easy to synthesize AuNPs and AgNPs. The AuNPs-leaf were synthesized using microwave radiation, while the AgNPs-leaf were synthesized using UV light radiation. The antioxidant activity of the extract, determined by ABTS, showed a decrease of 44.7% and 60.7% after the synthesis of the AuNPs-leaf and AgNPs-leaf, respectively. After the AgNPs-leaf synthesis, the concentration of polyphenols, reducing sugars and amino acids decreased by 15.4%, 38.7% and 46.8% in the leaf extract, respectively, while after the AuNPs-leaf synthesis only reducing sugars decreased by 67.7%. These results suggest that these groups of molecules are implicated in the reduction/stabilization of the nanoparticles. Although the contribution of these compounds in the synthesis of the AuNPs-leaf and the AgNPs-leaf was different. Finally, the AgNPs-leaf inhibited the growth of S. aureus, E. coli, S. marcescens and E. faecalis. All of them are bacterial strains of clinical importance due to their fast antibiotic resistance development

Selenium nanoparticles based on Amphipterygium glaucum extract with antibacterial, antioxidant, and plant biostimulant properties

Abstract Background In recent years, crop production has expanded due to the variety of commercially available species. This increase in production has led to global competition and the search for biostimulant products that improve crop quality and yield. At the same time, agricultural products that protect against diseases caused by phytopathogenic microorganisms are needed. Thus, the green synthesis of selenium nanoparticles (SeNPs) is a proposal for achieving these needs. In this research, SeNPs were synthesized from methanolic extract of Amphipterygium glaucum leaves, and chemically and biologically characterized. Results The characterization of SeNPs was conducted by ultraviolet–visible spectrophotometry (UV–Vis), scanning electron microscopy (SEM), electron microscopy transmission (TEM), Dynamic Light Scattering (DLS), energy dispersion X-ray spectroscopy (EDX), and infrared spectrophotometry (FTIR) techniques. SeNPs with an average size of 40–60 nm and spherical and needle-shaped morphologies were obtained. The antibacterial activity of SeNPs against Serratia marcescens, Enterobacter cloacae, and Alcaligenes faecalis was evaluated. The results indicate that the methanolic extracts of A. glaucum and SeNPs presented a high antioxidant activity. The biostimulant effect of SeNPs (10, 20, 50, and 100 µM) was evaluated in vinca (Catharanthus roseus), and calendula (Calendula officinalis) plants under greenhouse conditions, and they improved growth parameters such as the height, the fresh and dry weight of roots, stems, and leaves; and the number of flowers of vinca and calendula. Conclusions The antibacterial, antioxidant, and biostimulant properties of SeNPs synthesized from A. glaucum extract demonstrated in this study support their use as a promising tool in crop production. Graphical Abstrac