Assessment of Size-Dependent Antimicrobial and Cytotoxic Properties of Silver Nanoparticles

Nanoscale silver has been increasingly applied to commercial products for their antimicrobial function as antibiotics and disinfectants. In this work, the different sizes of silver nanoparticles (AgNPs) were studied not only in Methylobacterium spp. for their antimicrobial potential but also in human peripheral blood mononuclear cells (PBMCs) for their cytotoxicity in order to determine responses dependent on their particle size. Size controlled silver particles were prepared by chemical reduction of silver cations (Ag+) and then dispersed in water for their physicochemical characterization using transmission electron microscopy (TEM), dynamic light scattering (DLS), and zeta potential measurements. To ascertain antimicrobial response, water-soluble silver nanoparticles were mixed into Methylobacterium spp. cultured for two days and the sample from the broth was spread on the agar plate for colony counting. 10 nm nanoparticles showed more antimicrobial activity than 100 nm particles at which concentrations were equivalently controlled. Increased cytotoxic effect of smaller silver nanoparticles was also observed in PBMCs cocultured with particles. Silver ions released from 10 nm particles might be correlated with upregulated antimicrobial and cytotoxic properties of AgNPs

Insect Fauna of Mt. Jang-san, Yeongwol-gun, Gangwon-do, Korea

AbstractAn entomofauna study of Jangsan Mountain (1,408.8 m) in Yeongwol-gun, Gangwon-do was carried out from April to September, 2010. The distribution of 384 species, 91 families and 12 orders was confirmed from the study area

Fabrication of core/shell ZnWO4/carbon nanorods and their Li electroactivity

Carbon-coated ZnWO4 [C-ZW] nanorods with a one-dimensional core/shell structure were synthesised using hydrothermally prepared ZnWO4 and malic acid as precursors. The effects of the carbon coating on the ZnWO4 nanorods are investigated by thermogravimetry, high-resolution transmission electron microscopy, and Raman spectroscopy. The coating layer was found to be in uniform thickness of approximately 3 nm. Moreover, the D and G bands of carbon were clearly observed at around 1,350 and 1,600 cm-1, respectively, in the Raman spectra of the C-ZW nanorods. Furthermore, lithium electroactivities of the C-ZW nanorods were evaluated using cyclic voltammetry and galvanostatic cycling. In particular, the formed C-ZW nanorods exhibited excellent electrochemical performances, with rate capabilities better than those of bare ZnWO4 nanorods at different current rates, as well as a coulombic efficiency exceeding 98%. The specific capacity of the C-ZW nanorods maintained itself at approximately 170 mAh g-1, even at a high current rate of 3 C, which is much higher than pure ZnWO4 nanorods

Insect Fauna of Island Gangwha-do with its nearby Islands, Incheon Metropolitan city, Korea

AbstractThis study was conducted to clarify the current status of insects of Is. Gangwha-do (Mt. Goryeo-san, 436 m) as well as some nearby islands (Is. Gyodong-do, Is. Boleum-do, Is. Jumun-do and Is. Seokmo-do (Mt. Haemyeong-san, 327 m)) through June and September, 2009. A total of 206 insects of 104 species of 38 families and 6 orders was investigated by this survey

Thermally-Induced Actuations of Stimuli-Responsive, Bicompartmental Nanofibers for Decoupled Drug Release

Stimuli-responsive anisotropic microstructures and nanostructures with different physicochemical properties in discrete compartments, have been developed as advanced materials for drug delivery systems, tissue engineering, regenerative medicine, and biosensing applications. Moreover, their stimuli-triggered actuations would be of great interest for the introduction of the functionality of drug delivery reservoirs and tissue engineering scaffolds. In this study, stimuli-responsive bicompartmental nanofibers (BCNFs), with completely different polymer compositions, were prepared through electrohydrodynamic co-jetting with side-by-side needle geometry. One compartment with thermo-responsiveness was composed of methacrylated poly(N-isopropylacrylamide-co-allylamine hydrochloride) (poly(NIPAM-co-AAh)), while the counter compartment was made of poly(ethylene glycol) dimethacrylates (PEGDMA). Both methacrylated poly(NIPAM-co-AAh) and PEGDMA in distinct compartments were chemically crosslinked in a solid phase by UV irradiation and swelled under aqueous conditions, because of the hydrophilicity of both poly(NIPAM-co-AAh) and PEGDMA. As the temperature increased, BCNFs maintained a clear interface between compartments and showed thermally-induced actuation at the nanoscale due to the collapsed poly(NIPAM-co-AAh) compartment under the PEGDMA compartment of identical dimensions. Different model drugs, bovine serum albumin, and dexamethasone phosphate were alternately loaded into each compartment and released at different rates depending on the temperature and molecular weight of the drugs. These BCNFs, as intelligent nanomaterials, have great potential as tissue engineering scaffolds and multi-modal drug delivery reservoirs with stimuli-triggered actuation and decoupled drug release