Showing papers by "Kyusik Yun published in 2018"

Synthesis of ZnO nanoparticles-decorated spindle-shaped graphene oxide for application in synergistic antibacterial activity.

Abstract: A novel spindle-shaped graphene oxide (GO) was performed by the self-assembly of graphene oxide in the DMF. Loading uniform ZnO nanoparticles on spindle-shaped GO is used to study antibacterial property. In the ZnO/GO composites, spindle-shaped GO possessed special structure that was crumpled together with a length of ~1.0 μm and a mean diameter of 100 nm, and spherical ZnO particles with a diameter of 50 nm were fully characterized by field-emission scanning electron microscope (FE-SEM), a high-resolution transmission electron microscope (HR-TEM) and X-ray diffraction (XRD). Due to the antibacterial advantages of ZnO and GO, the mechanism underlying the interaction between composites and bacteria is elucidated in this work. The results showed that the composites could prevent bacterial proliferation and could destroy bacterial integrated membrane by the release of Zn2+ and generation of abundant reactive oxygen species (ROS). The typical gram-negative (Escherichia coli and Salmonella typhimurium) and gram-positive (Bacillus subtilis and Enterococcus faecalis) bacteria were used to investigate the significant antibacterial activity of ZnO/GO composites. The minimum inhibit concentration (MIC) value of ZnO/GO composites for the gram-positive bacteria was 31.25 ± 0.25 μg/mL, however, that for the gram-negative bacteria was 15.625 ± 0.5 μg/mL. Based on our study, this new structure composites with good antibacterial activity is regarded as a promising material for application in the medical field.

Photoluminescent AuNCs@UiO-66 for Ultrasensitive Detection of Mercury in Water Samples.

Abstract: In this work, we synthesized gold nanoclusters within a Zirconium-based metal–organic framework (AuNCs@UiO-66) that may create new prospects for the development of novel sensing materials for biosensor applications. The resulting AuNCs@UiO-66 nanocomposite exhibits red fluorescence with a high quantum yield (11%), and the AuNCs are homogeneously distributed along UiO-66. Analytical and morphological characterizations of the resulting material were carried out by UV–visible spectroscopy, photoluminescence spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction, and high-resolution transmission electron microscopy. The synthesized AuNCs@UiO-66 nanocomposite was used for the effective detection of Hg2+ ions with a detection limit as low as 77 pM. Moreover, the fabricated sensors also successfully detected Hg2+ in real water samples. This sensor is stable and highly fluorescent, developed using a simple fabrication method, and would be constructive for the detection of other metal ions and in biolog...

Surface functionalized magnetic nanoparticles shift cell behavior with on/off magnetic fields.

Abstract: Magnetic nanoparticles (MNPs) are used as contrast agents and targeted drug delivery systems (TDDS) due to their favorable size, surface charge, and magnetic properties. Unfortunately, the toxicity associated with MNPs limits their biological applications. Surface functionalization of MNPs with selective polymers alters the surface chemistry to impart better biocompatibility. We report the preparation of surface functionalized MNPs using iron oxide NPs (MNPs), poly (lactic-co-glycolic acid) (PLGA), and sodium alginate via co-precipitation, emulsification, and electro-spraying, respectively. The NPs are in the nanosize range and negatively charged. Morphological and structural analyses affirm the surface functionalized nanostructure of the NPs. The surface functionalized MNPs are biocompatible, and demonstrate enhanced intracellular delivery under an applied magnetic field (H), which evinces the targeting ability of MNPs. After NP treatment, the physico-mechanical properties of fibroblasts are decided by the selective MNP uptake under "on" or "off" magnetic field conditions. We envision potential use of biocompatible surface functionalized MNP for intracellular-, targeted-DDS, imaging, and for investigating cellular mechanics.

Large Instrument- and Detergent-Free Assay for Ultrasensitive Nucleic Acids Isolation via Binary Nanomaterial

Abstract: Nucleic acid-based diagnostics are widely used for clinical applications due to their powerful recognition of biomolecule properties. Isolation and purification of nucleic acids such as DNA and RNA in the diagnostic system have been severely hampered in point-of-care testing because of low recovery yields, degradation of nucleic acids due to the use of chaotropic detergent and high temperature, and the requirement of large instruments such as centrifuges and thermal controllers. Here, we report a novel large instrument- and detergent-free assay via binary nanomaterial for ultrasensitive nucleic acid isolation and detection from cells (eukaryotic and prokaryotic). This binary nanomaterial couples a zinc oxide nanomultigonal shuttle (ZnO NMS) for cell membrane rupture without detergent and temperature control and diatomaceous earth with dimethyl suberimidate complex (DDS) for the capture and isolation of nucleic acids (NA) from cells. The ZnO NMS was synthesized to a size of 500 nm to permit efficient cell ...

Dual Applicability of Polyaniline Coated Gold Nanorods: A Study of Antibacterial and Redox Activity

Abstract: Non-agglomerated, dual-purpose monodispersed gold nanorods (GNRs) were synthesized by using a seed-mediated method, and subsequent in situ chemical polymerization yielded polyaniline-coated gold nanorods (PANI-GNRs). The synthesized GNRs and PANI-GNRs were characterized by electron microscopic analyses, selected-area electron diffraction patterns, and element analyses. The prepared nanomaterials had an average length of 40±0.4 nm and a diameter of 15±0.2 nm. Furthermore, the PANI coating around the GNRs had a thickness of ~21 nm. These nanomaterials were also characterized by ultraviolet- visible and Fourier transform-infrared spectroscopies. While the absorption peaks of GNRs were observed at 520 and 675 nm, those of PANI-GNRs showed absorption maxima at 325 and 665 nm. The combination of 0.91 vol% of aniline with 5 mL of GNRs provided better electrochemical properties at 0.52 V and 1.30 V. The minimum inhibitory concentrations of laser-irradiated PANI-GNRs, PANI-GNRs, and laser-irradiated GNRs against Escherichia coli and Staphylococcus aureus were determined by using the micro-dilution method and compared to those of kanamycin (standard drug), revealing the significant bactericidal activity of laser-irradiated PANI-GNRs. This activity of the PANI-GNRs was also supported by the results of fluorescence and atomic force microscopy imaging. Thus, the synthesized nanomaterials can be potentially utilized for waste water treatment and biomedical/ pharmaceutical applications.

Synthesis of gold nanomaterials and their cancer-related biomedical applications: an update

Abstract: Recently, the advances in the synthesis of new types of nanomaterials have created several opportunities in drug delivery and targeted therapy applications Among the various nanostructures, gold nanostructures with controllable physical and chemical properties have received attention for various biomedical uses, including sensing of biomolecules, in vitro and in vivo bioimaging (as advanced contrast agents for photothermal and bioimaging techniques), photothermolysis of cancer cells, and targeted drug delivery The attractive properties of gold nanomaterials, particularly, anti-angiogenic properties, are highly useful in a variety of cancers studies In addition, they can bind many proteins and drugs and can be actively targeted to cancer cells over-expressing cell surface receptors and they are biocompatible in nature with a high atomic number, which directs to greater absorption of kilovoltage X-rays and provides greater contrast than standard agents In this review, we have summarized the synthesis, structure and functionalization of gold nanostructures, and their biomedical applications with special reference to cancer studies

Fluorometric 'switch-on' detection of heparin based on a system composed of rhodamine-labeled chitosan oligosaccharide lactate, and graphene oxide

Abstract: A novel fluorescence 'Switch on' for the detection of heparin based on the RhB-COL/GO system was achieved. A strong fluorescence dye, Rhodamine B, was modified by chitosan oligosaccharide lactate (COL), which plays a major role in the formation of a positively charged RhB-COL complex. RhB-COL was soluble and stable in solution, which was characterized by using Fourier transform infrared spectroscopy and x-ray photoelectron spectroscopy. GO sheets quenched the fluorescence intensity of RhB-COL due to electron transfer from RhB to the GO surface. The decrease in fluorescence intensity of RhB-COL with increasing GO concentration was recorded using a Cary Eclipse fluorescence spectrophotometer. On the other hand, the addition of heparin replaced GO to bind with the RhB-COL surface via an electrostatic and noncovalent bond due to the abundant negative charge, which resulted in recovery of the fluorescence intensity. This RhB-COL/GO system possessed high selectivity and good sensitivity for the detection of heparin compared to other biomolecules, such as glycine, D-glucose, hyaluronic acid, L-glutamic acid, and ascorbic acid. The linear response toward heparin was measured over the range, 0-1.8 U · ml-1, with a low detection limit of 0.04 U · ml-1. The satisfactory sensing performance of RhB-COL/GO for heparin supports new 'switch-on' sensor applications in heparin-related biomedical detection.