In this work we investigated the antibacterial properties of differently shaped silver nanoparticles against the gram-negative bacterium Escherichia coli, both in liquid systems and on agar plates. Energy-filtering transmission electron microscopy images revealed considerable changes in the cell membranes upon treatment, resulting in cell death. Truncated triangular silver nanoplates with a {111} lattice plane as the basal plane displayed the strongest biocidal action, compared with spherical and rod-shaped nanoparticles and with Ag ؉ (in the form of AgNO 3 ). It is proposed that nanoscale size and the presence of a {111} plane combine to promote this biocidal property. To our knowledge, this is the first comparative study on the bactericidal properties of silver nanoparticles of different shapes, and our results demonstrate that silver nanoparticles undergo a shape-dependent interaction with the gram-negative organism E. coli.Over the past few decades, inorganic nanoparticles, whose structures exhibit significantly novel and improved physical, chemical, and biological properties, phenomena, and functionality due to their nanoscale size, have elicited much interest. Nanophasic and nanostructured materials are attracting a great deal of attention because of their potential for achieving specific processes and selectivity, especially in biological and pharmaceutical applications (5, 39).Discoveries in the past decade have demonstrated that the electromagnetic, optical, and catalytic properties of noble-metal nanocrystals are strongly influenced by shape and size (6,26). This has motivated an upsurge in research on the synthesis routes that allow better control of shape and size (18,34,41), with projected applications in nanoelectronics and spectroscopy (14,19,36).Recent studies have demonstrated that specially formulated metal oxide nanoparticles have good antibacterial activity (33), and antimicrobial formulations comprising nanoparticles could be effective bactericidal materials (11,12).Among inorganic antibacterial agents, silver has been employed most extensively since ancient times to fight infections and control spoilage. The antibacterial and antiviral actions of silver, silver ion, and silver compounds have been thoroughly investigated (28,29,37). However, in minute concentrations, silver is nontoxic to human cells. The epidemiological history of silver has established its nontoxicity in normal use. Catalytic oxidation by metallic silver and reaction with dissolved monovalent silver ion probably contribute to its bactericidal effect (17). Microbes are unlikely to develop resistance against silver, as they do against conventional and narrow-target antibiotics, because the metal attacks a broad range of targets in the organisms, which means that they would have to develop a host of mutations simultaneously to protect themselves. Thus, silver ions have been used as an antibacterial component in dental resin composites (15), in synthetic zeolites (22), and in coatings of medical devices (2).Recent literature r...

Although human lysyl-tRNA synthetase (KRS), an enzyme for protein synthesis, is often highly expressed in various cancer cells, its pathophysiological implications have not been understood. Here we found that KRS induces cancer cell migration through interaction with the 67-kDa laminin receptor (67LR) that is converted from ribosomal subunit p40. On laminin signal, KRS was phosphorylated at the T52 residue by p38MAPK and dissociated from the cytosolic multi-tRNA synthetase complex for membrane translocation. The importance of T52 phosphorylation for membrane translocation of KRS was confirmed by site-directed mutagenesis. In the membrane, turnover of 67LR was controlled by Nedd4-mediated ubiquitination, and KRS inhibited ubiquitin-dependent degradation of 67LR, thereby enhancing laminin-induced cell migration. This work thus unveiled a unique function of KRS in the control of cell migration and its pathological implication in metastasis.

Advancements in nano-structured materials have facilitated several applications of nanoparticles (NPs). Skin penetration of NPs is a crucial factor for designing suitable topical antibacterial agents with low systemic toxicity. Available reports focus on size-dependent skin penetration of NPs, mainly through follicular pathways. Herein, for the first time, we demonstrate a proof-of-concept study that entails variations in skin permeability and diffusion coefficients, penetration rates and depth-of-penetration of differently shaped silver NPs (AgNPs) via intercellular pathways using both in vitro and in vivo models. The antimicrobial activity of AgNPs is known. Different shapes of AgNPs may exhibit diverse antimicrobial activities and skin penetration capabilities depending upon their active metallic facets. Consideration of the shape dependency of AgNPs in antimicrobial formulations could help developing an ideal topical agent with the highest efficacy and low systemic toxicity.

Highly monodispersed nanoparticles of a trivalent silver polydiguanide complex are synthesized by oxidation of the monovalent silver, followed by stabilization of the oxidized higher-valent metal through complexation with a polydiguanide ligand in a reverse microemulsion at room temperature. The synthesized nanoparticles have excellent photostability and displayed superior antibacterial activity toward Gram-positive and Gram-negative prokaryotes of clinical interest in vitro compared to silver sulfadiazine. These nanoparticles may serve as a new generation antibacterial metallopharmaceutical in wound care.

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