Narrow Results

In this work, we report the facile formation of bimetallic nanoparticles of Au–Pt in the presence of the plant polyphenol ellagic acid (EA). It was found that EA formed micro-fibrillar assemblies, which aggregated into micro-bundles under aqueous conditions. Those micro-bundles acted as templates for the growth of Au nanoparticles, as well as bimetallic Au–Pt nanoparticles biomimetically. At higher concentrations of EA, it was observed that in addition to forming fibrous micro-bundles, columnar assemblies of EA were formed in the presence of the metal nanoparticles. The formation of the assemblies was found to be concentration dependent. It appears that upon binding to metal ions and subsequent formation of the nanoparticles, morphological changes occur in the case of EA assemblies. The morphological changes observed were probed by electron microscopy. Further, the ability of the materials to degrade the toxic aromatic nitro compound 2-methoxy-4-nitroaniline was explored, where 50% degradation was observed within 15 min, indicating that such hybrid materials may have potential applications in environmental remediation.

The synthesis, characterization and application of biologically synthesized nanomaterials have become an important branch of nanotechnology. In the present study, we report the synthesis of silver nanoparticles from fresh leaf extract of Centella asiatica (LEC). UV-Vis spectrum for silver colloids contains a strong plasmon band near 425nm, which confirms the formation of nanoparticles. The experimental results show that the silver nanoparticles are formed easily in the extract at ambient temperature. The resulting silver nanoparticles (AgNPs) were in the spherical form and the average size of the nanoparticles was in the range from 3nm to 30nm. From the above silver nanoparticles, we were taken up to investigate the effects of various concentrations of AgNPs on growth, development and yield of peanut plants. The results of the present experiment showed that the optimized concentration of AgNPs of the good germination, growth and pod yield of peanut plant is 5ppm.

Numerical simulations for local buckling and postbuckling behavior of plant stems are presented under two combined loading cases: (1) axial compression (caused by axial grains) combined with wind pressure; and (2) bending moment (caused by eccentric axial grains) combined with wind pressure. Based on its microstructure, a hollow plant stem is modeled as a stringer stiffened multiwalled shell. The material properties of the stem are assumed to be orthotropic. The nonlinear governing equations for buckling and postbuckling of plant stems are solved through arc-length method along with Newton–Raphson technique. The numerical calculations are carried out using the finite element package ABAQUS. The results show that the postbuckling equilibrium path is unstable for plant stems subjected to axial compression or bending combined with relatively low values of wind pressure. Large reduction in buckling load and in postbuckling strength can be found even if the applied wind pressure is relatively small, which results in the easy occurrence of stem lodging.

Pinecone scales and seedpod valves can deform in response to environmental humidity change, which is categorized as nastic movements. In this article, inspired by their tissue structure, we use fiber-embedded gels to model the nastic movements of pinecone scales and seedpod valves. In the model, stiffer and less swellable fibers orient inhomogeneously in the gel matrix. Depending on the arrangement of fibers, the gel matrix may bend or twist when it shrinks, caused by the decrease of environmental humidity. Our simulations demonstrate the possibilities of achieving different deformation modes in fiber-embedded gels through initially specified fiber arrangements. The numerical modeling methods presented in the article may find their applications in biomimetic designs with responsive gels.

To repair bone defects, an important approach is to fabricate tissue engineering scaffolds as substitutions to replace auto-/allologous bones. Currently, processing a biomaterial into three-dimensional porous scaffolds and incorporating the calcium phosphate (Ca–P) nanoparticles into scaffolds profile two main characteristics of bone tissue engineering scaffolds. Based on this fact, in this paper we describe the design principles of the Ca–P nanoparticle-based and porous bone tissue engineering scaffolds. Then we summarize a variety of the Ca–P nanoparticle-based scaffolds, including discussion of the integration of the Ca–P nanoparticles with ceramics and polymers, followed by introduction of safety of the Ca–P nanoparticles in scaffolds.

Hierarchical self-assembling of materials represents one of the most appealing subjects in nanoscience, since bottom-up strategies allow for tailor-made synthesis of functional structures in commodities as well as in living systems. Herein we show that nanorings of ca. 10nm silica nanoparticles without any inorganic metal oxide or organic participant are able to spontaneously self-assemble presenting sophisticated forms and hierarchy. It was observed that after synthesis, silica nanoparticles are chaotically distributed but during storage at ambient conditions they spontaneously form self-assembled aggregates with multiplicity of morphologies when a small amount of water is added in the environment. Detailed description of the morphology of such structures by high resolution transmission electron microscope (HRTEM) is presented together with a discussion about the role of water during their spontaneous formation.

In this study, poly (lactic acid-glycolic acid) (PLGA) nanoparticles loaded with anti-inflammatory drug ketoprofen (KET) were prepared and then coated with platelet membrane (PLTM) to form KET@PLTM-PLGA nano-particles (NPs). The particle size of the KET@PLTM-PLGA NPs is 176nm and the surface protein is the same as that of PLTM. The results of confocal microscopy and flow cytometry showed that the KET@PLTM-PLGA NPs uptake of RAW264.7 induced by LPS was significantly higher than that of KET@PLGA NPs, without PLTM, which was due to the binding of P-selectin to CD44 receptors on the surface of RAW264.7 cells induced by LPS on the surface of PLTM. Compared with other KET preparations, KET@PLTM-PLGA NPs have better anti-inflammatory effect.

With the benefit of millions of years of natural selection, it is no surprise that when it comes to fitting form to function, Nature is second to none in engineering the right structure for the right job. The creation of architectural elegance, despite using the minimal amount of material has long fascinated man, who has endeavored to understand how intricate construction can be accomplished merely through the flow of inorganic ions and strategically placed macromolecules. When the demands of the environment are the blueprints of the construction, structures are produced with the utmost efficiency. This was first stated explicitly by D'Arcy Thompson, in his seminal work On Growth and Form (1917).¹ However, even as far back as the 16th century, scientist and astronomer Johannes Kepler noted that “Nature uses as little as possible of anything”. Both these and many other luminaries held Nature in the highest esteem as an engineer par excellence.

In the 19th century, people used these tenets and took their inspiration for daring and innovative architectural and engineering projects from Nature. In the 21st century therefore, when advanced nanoscale materials are required, it is only right that man should once again turn to Nature for solutions to their creation.