c Silver nanoparticles (AgNPs) are considered to be a potentially useful tool for controlling various pathogens. However, there are concerns about the release of AgNPs into environmental media, as they may generate adverse human health and ecological effects. In this study, we developed and evaluated a novel micrometer-sized magnetic hybrid colloid (MHC) decorated with variously sized AgNPs (AgNP-MHCs). After being applied for disinfection, these particles can be easily recovered from environmental media using their magnetic properties and remain effective for inactivating viral pathogens. We evaluated the efficacy of AgNP-MHCs for inactivating bacteriophage X174, murine norovirus (MNV), and adenovirus serotype 2 (AdV2). These target viruses were exposed to AgNP-MHCs for 1, 3, and 6 h at 25°C and then analyzed by plaque assay and real-time TaqMan PCR. The AgNP-MHCs were exposed to a wide range of pH levels and to tap and surface water to assess their antiviral effects under different environmental conditions. Among the three types of AgNP-MHCs tested, Ag30-MHCs displayed the highest efficacy for inactivating the viruses. The X174 and MNV were reduced by more than 2 log 10 after exposure to 4.6 ؋ 10 9 Ag30-MHCs/ml for 1 h. These results indicated that the AgNP-MHCs could be used to inactivate viral pathogens with minimum chance of potential release into environment. With recent advances in nanotechnology, nanoparticles have been receiving increased attention worldwide in the fields of biotechnology, medicine, and public health (1, 2). Owing to their high surface-to-volume ratio, nano-sized materials, typically ranging from 10 to 500 nm, have unique physicochemical properties compared with those of larger materials (1). The shape and size of nanomaterials can be controlled, and specific functional groups can be conjugated on their surfaces to enable interactions with certain proteins or intracellular uptake (3-5).Silver nanoparticles (AgNPs) have been widely studied as an antimicrobial agent (6). Silver is used in the creation of fine cutlery, for ornamentation, and in therapeutic agents. Silver compounds such as silver sulfadiazine and certain salts have been used as wound care products and as treatments for infectious diseases due to their antimicrobial properties (6, 7). Recent studies have revealed that AgNPs are very effective for inactivating various types of bacteria and viruses (8-11). AgNPs and Ag ϩ ions released from AgNPs interact directly with phosphorus-or sulfur-containing biomolecules, including DNA, RNA, and proteins (12-14). They have also been shown to generate reactive oxygen species (ROS), causing membrane damage in microorganisms (15). The size, shape, and concentration of AgNPs are also important factors that affect their antimicrobial capabilities (8,10,13,16,17).Previous studies have also highlighted several problems when AgNPs are used for controlling pathogens in a water environment. First, existing studies on the effectiveness of AgNPs for inactivating viral pathogens in water are limite...

The structure of proton transport channels is controlled and fixed in sulfonated poly(styrene-b-butadiene-b-styrene) (SBS) triblock copolymer membranes. Microphase-separated SBS membranes were cross-linked by UV irradiation in the presence of a photoinitiator and then sulfonated by acetyl sulfate. Sulfonated cross-linked SBS (scSBS) membranes with fixed nanosized proton transport channels were then prepared. The scSBS membranes show good proton conductivity, comparable to that of Nafion, and a low methanol permeability, more than 1 order of magnitude smaller than that of Nafion. Sulfonated non-cross-linkable poly(styrene-b-(ethylene-r-butylene)-b-styrene) membranes and sulfonated cross-linked poly(styrene-r-butadiene) membranes, which have less developed proton transport channels, were also prepared for comparison. The effects of the presence and size of the proton transport channels on the proton conductivity and methanol permeability were investigated. It is concluded that both the structure and the fixation of the proton transport channels are crucial to the functioning of proton exchange membranes of direct methanol fuel cells.

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The major challenges in practically utilising the immense potential benefits of nanomaterials are controlling aggregation, recycling the nanomaterials, and fabricating well-defined nanoparticulate materials using innovative methods. We present a novel innovative synthetic strategy for core–shell bimetallic nanoparticles that are well-defined, ligand-free, and robustly fixed on the outermost surface of recyclable magnetic silica microspheres. The strategy includes seeding, coalescing the seeds to cores, and then growing shells from the cores on aminopropyl-functionalised silica microspheres so that the cores and aminopropyl moieties are robustly embedded in the shell materials. The representative Au–Ag bimetallic nanoparticles fixed on the microsphere showed excellent catalytic performance that remained consistent during repeated catalytic cycles.

Abstract:Gold nanoshells (~160 nm in diameter) were encapsulated within a shell of temperature-responsive poly(N-isopropylacrylamide-co-acrylic acid) (P(NIPAM-co-AA)) using a surface-bound rationally-designed free radical initiator in water for the development of a photothermally-induced drug-delivery system. The morphologies of the resultant hydrogel-coated nanoshells were analyzed by scanning electron microscopy (SEM), while the temperature-responsive behavior of the nanoparticles was characterized by dynamic light scattering (DLS). The diameter of the P(NIPAM-co-AA) encapsulated nanoshells decreased as the solution temperature was increased, indicating a collapse of the hydrogel layer with increasing temperatures. In addition, the optical properties of the composite nanoshells were studied by UV-visible spectroscopy. The surface plasmon resonance (SPR) peak of the hydrogel-coated nanoshells appeared at~800 nm, which lies within the tissue-transparent range that is important for biomedical applications. Furthermore, the periphery of the particles was conjugated with the model protein avidin to modify the hydrogel-coated nanoshells with a fluorescent-tagged biotin, biotin-4-fluorescein (biotin-4-FITC), for colorimetric imaging/monitoring.

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Although the current array of nanomachines mostly comprises simple devices (at least from a mechanical viewpoint), the underlying physical and chemical interactions that play key roles in the 'assembly' of these machines have required decades of research to ascertain a fundamental understanding of how such processes can be manipulated at the nanoscale. In this review, we wish to convey a realistic picture of the current developments in the design and implementation of nanomachines, with an emphasis on how these developments are leading to practical applications in medicine, including a sense of how such simple devices are rapidly becoming the building blocks for assembling the nanorobots of tomorrow.