Highly sensitive and selective visual detection of Cr(VI) ions based on etching of silver-coated gold nanorods

We report a visual detection of Cr(VI) ions using silver-coated gold nanorods (AuNR@Ag) as sensing probes. Au NRs were prepared by a seed-mediated growth process and AuNR@Ag nanostructures were synthesized by growing Ag nanoshells on Au NRs. Successful coating of Ag nanoshells on the surface of Au NRs was demonstrated with TEM, EDS, and UV–vis spectrometer. By increasing the overall amount of the deposited Ag on Au NRs, the localized surface plasmon resonance (LSPR) band was significantly blue-shifted, which allowed tuning across the visible spectrum. The sensing mechanism relies on the redox reaction between Cr(VI) ions and Ag nanoshells on Au NRs. As the concentration of Cr(VI) ions increased, more significant red-shift of the longitudinal peak and intensity decrease of the transverse peak could be observed using UV–vis spectrometer. Several parameters such as concentration of CTAB, thickness of the Ag nanoshells and pH of the sample were carefully optimized to determine Cr(VI) ions. Under optimized condition, this method showed a low detection limit of 0.4 μM and high selectivity towards Cr(VI) over other metal ions, and the detection range of Cr(VI) was tuned by controlling thickness of the Ag nanoshells. From multiple evaluations in real sample, it is clear that this method is a promising Cr(VI) ion colorimetric sensor with rapid, sensitive, and selective sensing ability.This research was supported under the framework of Nano Material Technology Development Program (NRF-2015M3A7B6027970) and Basic Science Research Program (NRF-2018R1D1A1B07051249) by National Research Foundation, South Korea. Also, this work was supported by the Center of Integrated Smart Sensors funded by the Ministry of Science, ICT and Future Planning, South Korea, as Global Frontier Project (CISS-012M3A6A6054186

Magnetic and near-infrared derived heating characteristics of dimercaptosuccinic acid coated uniform Fe@Fe3O4 core–shell nanoparticles

Among the number of hyperthermia materials, magnetic nanoparticles have received much attention. In this work, we studied the heating characteristics of uniform Fe@Fe3O4 core–shell nanoparticle under near-infrared laser irradiation and external AC magnetic field applying. The Fe@Fe3O4 core–shell nanoparticles were prepared by thermal decomposition of iron pentacarbonyl and followed by controlled oxidation. The prepared uniform particles were further coated with dimercaptosuccinic acid to make them well dispersed in water. Near-infrared derived photothermal study of solutions containing a different concentration of the core–shell nanoparticles was made by using 808 nm laser Source. Additionally, magnetic hyperthermia ability of the Fe@Fe3O4 nanoparticle at 150 kHz and various oersted (140–180 Oe) condition was systemically characterized. The Fe@Fe3O4 nanoparticles which exhibited effective photo and magnetic hyperthermia are expected to be used in biomedical application.This research was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (NRF-2018R1D1A1B07051249), Nano Material Technology Develop‑ment Program (NRF-2015M3A7B6027970) of MSIP/NRF and Center for Inte‑grated Smart Sensors funded by the Ministry of Science, ICT, and Future Plan‑ning, Republic of Korea, as Global Frontier Project (CISS-012M3A6A6054186)

규칙적인 다공성 알루미늄 피막을 이용한 나노물질의 제조에 대한 연구

Thesis(doctoral)--서울대학교 대학원 :화학부 전기화학전공,2004.Docto

Multifunctional nanostructured materials for multimodal imaging, and simultaneous imaging and therapy

Nanotechnology offers tremendous potential for future biomedical technology. Due to their unique characteristics including superparamagnetic or fluorescent properties, and small size comparable to biomolecules, nanostructured materials have emerged as novel bioimaging, diagnostic, and therapeutic agents for the future medical field. Especially, the combinations of various nanostructured materials with different properties can offer synergetic multifunctional nanomedical platforms, which make it possible to accomplish multimodal imaging, and simultaneous diagnosis and therapy. Moreover, the conjugation of targeting moieties on the surface of these multifunctional nanomaterials gives them specific targeted imaging and therapeutic properties. In this tutorial review, we will summarize the recent reports on the fabrication strategies of multifunctional nanoplatforms and their applications to targeted multimodal imaging and simultaneous diagnosis and therapy.

A solventless mix-bake-wash approach to the facile controlled synthesis of core-shell and alloy Ag-Cu bimetallic nanoparticles

We report a solventless mix-bake-wash method for the facile controlled synthesis of Ag-Cu core-shell and alloy bimetallic nanoparticles (NPs). Small bimetallic nanomaterials were prepared by a one-step heating process using salt powder as a template. The particle structure could be controlled by tuning the annealing temperature to generate hetero-structured core-shell NPs or homogeneous alloys. The NPs' bimetallic structure and elemental composition were characterized by HR-TEM, FE-SEM, EDX, HADDF-STEM, XRD and XPS. Whereas the as-synthesized Ag@Cu core-shell NPs consist of a core of face-centered cubic (fcc) polycrystalline Ag NPs and a shell of fcc Cu including trace amounts of copper oxides, the AgCu nanoalloy was found to comprise a single-phase NP with the same crystal structure as that of Ag, without the copper oxide species. Cyclic voltammetric measurements confirmed the chemical identification of the surface species and their stability to oxidation. This synthesis approach is facile, structure-controllable, and scalable, and is expected to be capable of producing other bimetallic or trimetallic nanomaterials. © The Royal Society of Chemistry 20156

Sea urchin shaped carbon nanostructured materials: carbon nanotubes immobilized on hollow carbon spheres

Novel sea urchin shaped nanostructured carbon spheres (carbon nano-urchins) were fabricated by the growth of carbon nanotubes on the surface of hollow carbon spheres. The carbon nano-urchins were successfully used as a catalyst support for methanol electrochemical oxidation. © The Royal Society of Chemistry 2006.close333

Designed fabrication of silica-based nanostructured particle systems for nanomedicine applications

Suitably integrating multiple nanomaterials into nanostructured particle systems with specific combinations of properties has recently attracted significant attention in the research community. In particular, numerous particle systems have been designed and fabricated by integrating diverse materials with monodispersed silica nanoparticles. One or more distinct nanomaterials can be assembled on, encapsulated within, or integrated both inside and on the surface of silica nanoparticles using different chemistries and techniques to create multifunctional nanosystems. Research on these particle systems for biomedical applications has progressed rapidly during recent years due to the synergistic advantages of these complexes compared to the use of single components. This feature article surveys recent research progress on the fabrication strategies of these nanoparticle systems and their applications to medical diagnostics and therapy, thereby paving the way for the emerging field of nanomedicine.

Porous Mn3O4 nanorod/reduced graphene oxide hybrid paper as a flexible and binder-free anode material for lithium ion battery

A highly flexible and free-standing, porous Mn3O4 nanorod/reduced graphene oxide (pMn3O4 NR/rGO) paper was prepared by a two-step process: vacuum filtration and thermal treatment. The MnOOH nanorod/graphene oxide (MnOOH NR/GO) paper obtained by a simple filtration method is transformed into pMn3O4 NR/rGO paper after a thermal reduction process. A unique lamellar structure was achieved with pMn3O4 NR homogeneously intercalated within the GO layers. In the hybrid structure, graphene nanosheets provide a conductive pathway and act as the buffer layers to prevent the pulverization of pMn3O4 NRs during reaction. Therefore, when used as the anode in lithium ion batteries, this pMn3O4 NR/rGO paper exhibits a first high discharge capacity of 943 mA h g-1, which quickly stabilizes and remains at 573 mA h g-1 even after 100 cycles at 100 mA h g-1, which is much higher than the discharge capacity of the corresponding pristine graphene paper (183 mA h g-1). © 2016 Elsevier Ltd120241sciescopu

Facile scalable synthesis of magnetite nanocrystals embedded in carbon matrix as superior anode materials for lithium-ion batteries

A simple and scalable process was developed for the synthesis of highly crystalline magnetite nanocrystals embedded in a carbon matrix using low cost starting materials; the resulting nano composite showed a very high specific capacity of 863 mA hg(-1) in the initial cycle and high capacity retention of 90% after 30 cycles.