Exploring the potential of plant-derived natural products beyond functional food: Applications in nanomedicine

The use of plant products as nutritional food and therapeutic agents is immemorial and intimately linked to the human life since its origin. Also, the tanning action of plant extracts has been hugely exploited to transform animal skins into leather from ancient times to present. However, the exploitation of the potential applications of the plant biomolecules in some of the modern technologies is rather now emerging. In fact, the power antioxidant, reducing and biological activities of the plant metabolites, together their chelating and their biodegradable properties, make the plant-derived natural products unique raw materials to design new sustainable approaches to prepare promising hybrid formulations and composites at the nanometer scale for innovative diagnostic and therapeutic procedures and nanotechnology applications. In the present contribution, some recent advances in this topic are briefly discussed

Estudio del mecanismo de magnetización en nanoelipsoides de Fe con microestructuras diseñadas, bioinspiradas en la bacteria magnetotáctica

En este trabajo se estudia la preparación de nanoelipsoides magnéticos mediante la reducción con hidrógeno de nanoarquitecturas alargadas compuestas de nanocristales de hematites altamente orientados. En particular, se estudia el efecto del tiempo de reducción en las propiedades microestructurales y magnéticas de los nanoelipsoides prestando especial atención al estudio de las fuentes de anisotropía magnética presentes en el sistema y el posible mecanismo de inversión de la magnetización. In this work, the preparation route of magnetic nanoellipsoids by the hydrogen reduction of elongated nanoarchitectures composed by highly oriented hematite nanocrystals is revised. In particular, the effect of the reduction time on the microstructural and magnetic properties of the nanoellipsoids are studied with special attention to the different magnetic sources and the possible magnetization reversal mechanism

Formación de partículas nanométricas en soluciones sobresaturadas

El estudio de los procesos asociados a la precipitación química en soluciones sobresaturadas es crucial para entender los mecanismos de algunos procesos naturales, como la biomineralización de estructuras biológicamente funcionales y la formación de rocas sedimentarias químicas. Por otra parte, este fenómeno puede emplearse en el laboratorio para sintetizar eficaz y versátilmente nuevos materiales de interés fundamental y práctico. En este trabajo se presenta una revisión de los fundamentos del fenómeno de la cristalización en soluciones sobresaturadas considerando su aplicación en la producción de nanopartículas uniformes con características controlables

Size distribution and frustrated antiferromagnetic coupling effects on the magnetic behavior of ultrafine akaganéite (β-FeOOH) nanoparticles

The magnetic properties of low dimensional materials of several iron oxyhydroxide phases, such as akaganéite (β-FeOOH) or lepidocrocite (γ-FeO(OH)), remain poorly explored, probably due to their specific preparation as single crystalline phase requires special conditions owing to their structural instability. In the present work, ultrafine akaganéite nanoparticles were prepared by the hydrolysis of FeCl3 solutions at room temperature induced by the presence of NaOH. The resulting product was characterized by several analytical techniques. Structural investigations using X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), and selected area electron diffraction (SAED) revealed that the sample was mainly constituted by rather-equiaxial akaganéite nanocrystals with mean diameter of 3.3 ± 0.5 nm. In addition, a small amount of rodlike akaganéite particles with 23 ± 5 nm in length and 5 ± 1 nm in width was also detected. The study of the respective dependences of the dc magnetization and the ac susceptibility on temperature and exciting magnetic field revealed complex magnetic relaxation processes, high coercivity values at low temperature, and exchange bias effect. These results have been tentatively explained considering size distribution effects and the presence of superparamagnetic and spin glass-like contributions arising from the frustration of the antiferromagnetic order owing to surface effects and an insufficient filling of the akaganéite channels with Cl- anions.Financial support from the Mexican Council of Science and Technology (CONACYT) and Universidad Autonoma de Nuevo León under research projects CB12-179486 and PAICYT-CE793-11, respectively, is acknowledged. Spanish funding under the MINECO research project MAT2010-20798-C05-04 and FEDER is also acknowledged.Peer Reviewe

Microstructural, spectroscopic, and antibacterial properties of silver-based hybrid nanostructures biosynthesized using extracts of coriander leaves and seeds

Coriander leaves and seeds have been highly appreciated since ancient times, not only due to their pleasant flavors but also due to their inhibitory activity on food degradation and their beneficial properties for health, both ascribed to their strong antioxidant activity. Recently, it has been shown that coriander leaf extracts can mediate the synthesis of metallic nanoparticles through oxidation/reduction reactions. In the present study, extracts of coriander leaves and seeds have been used as reaction media for the wet chemical synthesis of ultrafine silver nanoparticles and nanoparticle clusters, with urchin- and tree-like shapes, coated by biomolecules (mainly, proteins and polyphenols). In this greener route of nanostructure preparation, the active biocompounds of coriander simultaneously play the roles of reducing and stabilizing agents. The morphological and microstructural studies of the resulting biosynthesized silver nanostructures revealed that the nanostructures prepared with a small concentration of the precursor Ag salt (AgNO3 =5 mM) exhibit an ultrafine size and a narrow size distribution, whereas particles synthesized with high concentrations of the precursor Ag salt (AgNO3 =0.5 M) are polydisperse and formation of supramolecular structures occurs. Fourier transform infrared and Raman spectroscopy studies indicated that the bioreduction of the Ag- ions takes place through their interactions with free amines, carboxylate ions, and hydroxyl groups. As a consequence of such interactions, residues of proteins and polyphenols cap the biosynthesized Ag nanoparticles providing them a hybrid core/shell structure. In addition, these biosynthesized Ag nanomaterials exhibited size-dependent plasmon extinction bands and enhanced bactericidal activities against both Gram-positive and Gram-negative bacteria, displaying minimal inhibitory Ag concentrations lower than typical values reported in the literature for Ag nanoparticles, probably due to the synergy of the bactericidal activities of the Ag nanoparticle cores and their capping ligandsSEP CB12-17948

Plant growth-promoting rhizobacteria: a biofertilization alternative for sustainable agriculture.

Modern agriculture faces new challenges, integrating ecological and molecular approaches, to achieve higher crop yields and minimize environmental impacts. In order to generate higher yields, synthetic fertilizer doses per unit area have been significantly increased, which can cause pollution, damage to health and loss of soil fertility, becoming one of the most important concerns in agricultural production. To improve production without the use of synthetic fertilizers, research has been directed towards the development of new biotechnologies, leading to a growing interest in beneficial soil microorganisms that can promote plant growth and, in some cases, prevent infections of plant tissue by pathogens. The interactions of plant growth-promoting rhizobacteria (PGPR) with the biotic environment - plants and microorganisms - are very complex and use different mechanisms of action to promote plant growth. These mechanisms are grouped into: 1) Biofertilization; 2) Phytostimulation; and 3) Biocontrol. Inoculation of crops with PGRP substantially reduces the use of synthetic fertilizers and negative impacts on the soil, increases crop yields, and contributes to the producer's economy and the population's food supply. This review describes the basic aspects inherent to the interaction between the CVPGRs and plant species, focusing on the benefits that CVPGRs bring to agricultural activity

Confinement and surface effects on the physical properties of rhombohedral-shape hematite (α-Fe2O3) nanocrystals

Morphological, microstructural and vibrational properties of hematite (α-FeO) nanocrystals with a rhombohedral shape and rounded edges, obtained by forced hydrolysis of iron(III) solutions under a fast nucleation, have been investigated in detail as a function of aging time. These studies allowed us to propose a detailed formation mechanism and revealed that these nanocrystals are composed of four {104} side facets, two {110} faces at the edges of the long diagonal of the nanocrystals and two {-441} facets as the top and bottom faces. Also, the presence of nanoscopic pores and fissures was evidenced. The vibrational bands of such nanocrystals were shifted to lower frequencies in comparison with bulk hematite ones as the nanocrystal size was reduced due to phonon confinement effects. Also, the indirect and direct transition band gaps displayed interesting dependences on the aging time arising from quantum confinement and surface effectsConsejo Nacional de Ciencia y Tecnología CB-17948

Fenómenos físicos de las nanopartículas de oro

El oro ha sido uno de los materiales más preciados por el hombre desde la antigüedad por sus excelentes propiedades, entre las que destaca su hermoso color y brillo, su maleabilidad y su estabilidad química. En las últimas décadas, el interés por este material se ha incrementado al encontrar que el oro en forma de nanopartículas presenta fenómenos físicos nuevos que incrementan su potencial tecnológico. En esta contribución presentamos una breve descripción de algunos de estos fenómenos, los cuales son objeto de estudio del cuerpo académico física de los sistemas de baja dimensionalidad y sus aplicaciones de la FCFM de la UANL