Browsing by Author "Chen, Fu-Rong"

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30 nm resolution x-ray imaging at 8 keV using third order diffraction of a zone plate lens objective in a transmission microscope
(2006-11-27)
Yin, Gung-Chian
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Song, Yen-Fang
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Tang, Mau-Tsu
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Chen, Fu-Rong
;
Liang, Keng S.
A hard x-ray transmission microscope with 30 nm spatial resolution has been developed employing the third diffraction order of a zone plate objective. The microscope utilizes a capillary type condenser with suitable surface figure to generate a hollow cone illumination which is matched in illumination range to the numerical aperture of the third order diffraction of a zone plate with an outmost zone width of 50 nm. Using a test sample of a 150 nm thick gold spoke pattern with finest half-pitch of 30 nm, the authors obtained x-ray images with 30 nm resolution at 8 keV x-ray energy. (c) 2006 American Institute of Physics.
A Unique and Potent Protein Binding Nature of Liposome Containing Polyethylenimine and Polyethylene Glycol: A Nondisplaceable Property
(2011-06-01)
Liu, Yen-Ku
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Lin, Yu-Ling
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Chen, Chia-Hung
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Lin, Ching-Min
;
Ma, Kuan-Lun
Most of the currently available targeting vectors are produced via the linkage of targeting molecules. However, the coupling process is complicated, and the covalent linkage may attenuate the activity of certain targeting molecules. In this study, we have developed a cationic liposome complexed with polyethylenimine and polyethylene glycol polymers (LPPC) that can capture various proteins without covalent conjugation. Characterizations of prepared LPPC revealed that the maximal-binding capacity was about 170 mu g of bovine serum albumin to 40 mu g of sphere-shaped LPPC (180 nm). The proteins were essentially located at or near the surface when analyzed by atomic force or transmission electron microscopy. We demonstrate that polyethylenimine was an essential component to bind the proteins. Upon the saturation of captured proteins, a given protein could not be displaced by other additional proteins and still retained its biological activity. Using a variety of functional proteins, we show some typical examples of the utility of incorporated beta-glucuronidase and antibodies onto the LPPC. The beta-glucuronidase can be used for the study of antigen-antibody interactions, whereas in studies with the antibody complex, we used anti-CD3 as an agonist to stimulate the proliferation of peripheral blood mononuclear cells via a receptor-mediated mechanism and anti-VEGFR for cell staining. In conclusion, the prepared LPPC can provide a platform to capture biologically and biochemically functional proteins on its surface for various applications, such as cell signaling, cell profiling, noncovalent enzyme-linked immunoassays, and others not mentioned. Biotechnol. Bioeng. Biotechnol. Bioeng. 2011; 108: 1318-1327. (C) 2010 Wiley Periodicals, Inc.
Contact to ZnO and intrinsic resistances of individual ZnO nanowires with a circular cross section
(2007-05-28)
Lin, Yen-Fu
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Jian, Wen-Bin
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Wang, C. P.
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Suen, Yuen-Wuu
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Wu, Zhong-Yi
Single crystalline ZnO nanowires (NWs) with a circular cross section and similar to 40 nm in diameter have been synthesized and utilized to fabricate two-contact ZnO NW devices. The electrical properties of the NW devices can be categorized into two classes according to the magnitude of their room-temperature resistances. I-V curves of low-resistance devices exhibit downward bending features and their temperature dependent resistances demonstrate thermal activation transport in the ZnO NWs. The high-resistance NW devices can be modeled as back-to-back Schottky contacts and the electron transport through the contacts reveals a variable-range-hopping mechanism. (C) 2007 American Institute of Physics.
Dark field image of full-field transmission hard x-ray microscope in 8-11 keV
(2006-01-01)
Yin, Gung-Chian
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Duewer, Fred
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Zeng, Xianghui
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Lyon, Alan
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Yun, Wenbing
We have demonstrated dark-field imaging using a full-field hard x-ray microscope by using a custom capillary-based condenser. The condenser provides illumination with a numeric aperture about 3-mrad with high efficiency. This high illumination angle allows full-resolution imaging using a 50 rim hard x-ray zone plate. The zeroth order beam from the condenser is well out of the zoneplate range - which allows a high signal-to-noise ratio in the image plane. Small particles with high scattering power, such as colloidal gold markers used in biology are well-suited for dark-field imaging. Combining with high brightness source from NSRRC BL01B, the dark field image can be acquired within several minutes with high contrast ratio. In this paper, the dark field image of IC and the zoneplate defect will be demonstrated and studied in different energy under dark field mode.
Direct Formation of Wafer Scale Graphene Thin Layers on Insulating Substrates by Chemical Vapor Deposition
(2011-09-01)
Su, Ching-Yuan
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Lu, Ang-Yu
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Wu, Chih-Yu
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Li, Yi-Te
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Liu, Keng-Ku
Direct formation of high-quality and wafer scale graphene thin layers on insulating gate dielectrics such as SiO(2) is emergent for graphene electronics using Si-wafer compatible fabrication. Here, we report that in a chemical vapor deposition process the carbon species dissociated on Cu surfaces not only result in graphene layers on top of the catalytic Cu thin films but also diffuse through Cu grain boundaries to the interface between Cu and underlying dielectrics. Optimization of the process parameters leads to a continuous and large-area graphene thin layers directly formed on top of the dielectrics. The bottom-gated transistor characteristics for the graphene films have shown quite comparable carrier mobility compared to the top-layer graphene. The proposed method allows us to achieve wafer-sized graphene on versatile insulating substrates without the need of graphene transfer.
Four-probe electrical-transport measurements on single indium tin oxide nanowires between 1.5 and 300 K
(2009-03-11)
Chiu, Shao-Pin
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Chung, Hui-Fang
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Lin, Yong-Han
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Kai, Ji-Jung
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Chen, Fu-Rong
Single-crystalline indium tin oxide (ITO) nanowires (NWs) were grown by the standard thermal evaporation method. The as-grown NWs were typically 100-300 nm in diameter and a few mu m long. Four-probe submicron Ti/Au electrodes on individual NWs were fabricated by the electron-beam lithography technique. The resistivities of several single NWs have been measured from 300 down to 1.5 K. The results indicate that the as-grown ITO NWs are metallic, but disordered. The overall temperature behavior of resistivity can be described by the Bloch-Gruneisen law plus a low-temperature correction due to the scattering of electrons off dynamic point defects. This observation suggests the existence of numerous dynamic point defects in as-grown ITO NWs.
Growth of Cu nanobelt and Ag belt-like materials by surfactant-assisted galvanic reductions
(2007-05-08)
Huang, Ting-Kai
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Cheng, Tzu-Hou
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Yen, Ming-Yu
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Hsiao, Wei-Han
;
Wang, Lung-Shen
We demonstrate the syntheses of single crystalline Cu nanobelt and Ag belt-like materials via CTAC-assisted (CTAC, cetyltrimethylammonium chloride) galvanic reductions. The single crystalline face-centered cubic phase Cu nanobelt was prepared by reacting CuCl2(aq) with Al(s) in an aqueous solution of CTAC and HNO3. The Cu nanobelt exhibited a high-quality ribbon-like nanostructure with a thickness less than 15 nm, a width of 30-150 nm, and a length up to 10 mu m. The belt-like Ag, with a thickness less than 10 nm, a width of 30-100 nm, a length up to 5 mu m, and a novel single crystalline 4H structure, was prepared by reacting AgNO3(aq) and Cu(s) in an aqueous solution of CTAC.
Growth of high-aspect-ratio gold nanowires on silicon by surfactant-assisted galvanic reductions
(2008-06-03)
Huang, Ting-Kai
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Chen, Ying-Chieh
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Ko, Hsin-Chun
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Huang, Hsin-Wei
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Wang, Chia-Hsin
A simple galvanic reduction for direct growth of An nanowires on silicon wafers is developed. The nanowires were prepared by reacting HAuCl4(aq) with Sn-(s) in the presence of CTAC((aq)) (cetyltrimethylammonium chloride) and NaNO3(aq), which were important to the product morphology development. The nanowire diameter was 50-100 nm, and the length was more than 20 mu m.
Growth of single-crystalline RuO2 nanowires with one- and two-nanocontact electrical characterizations
(2007-01-01)
Liu, Yee-Lang
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Wu, Zong-Yi
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Lin, Kuei-Jiun
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Huang, Jr-Jeng
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Chen, Fu-Rong
Single-crystalline RuO2 nanowires were grown by using a thermal evaporation method. A control of the sizes (width and length) and the length-to-width ratio of the nanowires were achieved by tuning the growth time. A transmission electron microscope-scanning tunneling microscope technique invoking one-nanocontact electrical characterization was adopted to determine the room-temperature resistivity (similar to 100 mu Omega cm) of the nanowires. An e-beam lithography technique facilitating two-nanocontact measurements was performed to establish the metallic characteristic of individual nanowires. The authors found that a nanocontact may introduce high contact resistance, nonlinear current-voltage characteristics, and even semiconducting behavior in the temperature dependent resistance. (c) 2007 American Institute of Physics.
Laser induced popcornlike conformational transition of nanodiamond as a nanoknife
(2008-07-21)
Chang, Chia-Ching
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Chen, Pei-Hsin
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Chu, Hsueh-Liang
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Lee, Tzu-Cheng
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Chou, Ching-Chung
Nanodiamond (ND) is surrounded by layers of graphite on its surface. This unique structure feature creates unusual fluorescence spectra, which can be used as an indicator to monitor its surface modification. Meanwhile, the impurity, nitroso (C - N = O) inside the ND can be photolyzed by two-photon absorption, releasing NO to facilitate the formation of a sp(3) diamond structure in the core of ND and transforming it into a sp(2) graphite structure. Such a conformational transition enlarges the size of ND from 8 to 90 nm, resulting in a popcornlike structure. This transition reaction may be useful as nanoknives in biomedical application. (c) 2008 American Institute of Physics.
Magnetic Resonance Imaging of Mouse Islet Grafts Labeled with Novel Chitosan-Coated Superparamagnetic Iron Oxide Nanoparticles
(2013-04-29)
Juang, Jyuhn-Huarng
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Shen, Chia-Rui
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Wang, Jiun-Jie
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Kuo, Chien-Hung
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Chien, Yu-Wen
Object: To better understand the fate of islet isografts and allografts, we utilized a magnetic resonance (MR) imaging technique to monitor mouse islets labeled with a novel MR contrast agent, chitosan-coated superparamagnetic iron oxide (CSPIO) nanoparticles. Materials and Methods: After being incubated with and without CSPIO (10 mu g/ml), C57BL/6 mouse islets were examined under transmission electron microscope (TEM) and their insulin secretion was measured. Cytotoxicity was examined in alpha (alpha TC1) and beta (NIT-1 and beta TC) cell lines as well as islets. C57BL/6 mice were used as donors and inbred C57BL/6 and Balb/c mice were used as recipients of islet transplantation. Three hundred islets were transplanted under the left kidney capsule of each mouse and then MR was performed in the recipients periodically. At the end of study, the islet graft was removed for histology and TEM studies. Results: After incubation of mouse islets with CSPIO (10 mu g/mL), TEM showed CSPIO in endocytotic vesicles of alpha- and beta-cells at 8 h. Incubation with CSPIO did not affect insulin secretion from islets and death rates of alpha TC1, NIT-1 and beta TC cell lines as well as islets. After syngeneic and allogeneic transplantation, grafts of CSPIO-labeled islets were visualized on MR scans as persistent hypointense areas. At 8 weeks after syngeneic transplantation and 31 days after allogeneic transplantation, histology of CSPIO-labeled islet grafts showed colocalized insulin and iron staining in the same areas but the size of allografts decreased with time. TEM with elementary iron mapping demonstrated CSPIO distributed in the cytoplasm of islet cells, which maintained intact ultrastructure. Conclusion: Our results indicate that after syngeneic and allogeneic transplantation, islets labeled with CSPIO nanoparticles can be effectively and safely imaged by MR.
Phase tomography reconstructed by 3D TIE in hard X-ray microscope
(2007)
Yin, Gung-Chian
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Chen, Fu-Rong
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Pyun, Ahram
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Ho, Jung
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Hwu, Yeukuang
X-ray phase tomography and phase imaging are promising ways of investigation on low Z material- A polymer blend of PE/PS sample was used to test the 3D phase retrieval method in the parallel beam illuminated microscope. Because the polymer sample is thick, the phase retardation is quite mixed and the image can not be distinguished when the 2D transport intensity equation (TIE) is applied. In this study, we have provided a different approach for solving the phase in three dimensions for thick sample. Our method involves integration of 3D TIE/Fourier slice theorem for solving thick phase sample. In our experiment, eight sets of de-focal series image data sets were recorded covering the angular range of 0 to 180 degree. Only three set of image cubes were used in 3D TIE equation for solving the phase tomography. The phase contrast of the polymer blend in 3D is obviously enhanced, and the two different groups of polymer blend can be distinguished in the phase tomography.
Pulsatile Drug Release from PLGA Hollow Microspheres by Controlling the Permeability of Their Walls with a Magnetic Field
(2012-12-07)
Chiang, Wei-Lun
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Ke, Cherng-Jyh
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Liao, Zi-Xian
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Chen, San-Yuan
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Chen, Fu-Rong
Quantitative phase retrieval in transmission hard x-ray microscope
(2007-04-30)
Yin, Gung-Chian
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Chen, Fu-Rong
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Hwu, Yeukuang
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Shieh, Han-Ping D.
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Liang, Keng S.
Quantitative phase retrieval with a sub-100-nm resolution is achieved from micrographs of a zone plate based transmission x-ray microscope. A plastic zone plate containing objects of sizes from micrometers down to tens of nanometers is used as a test sample to quantify the retrieved phase. Utilizing the focal serial images in the image plane, the phase information is retrieved quantitatively across the entire range of sizes by combining the transport intensity equation and self-consistent wave propagation methods in this partial coherence system. The study demonstrates a solution to overcome the deficiency encountered in the two phase retrieval approaches. (c) 2007 American Institute of Physics.
Simple and Fast Method To Fabricate Single-Nanoparticle-Terminated Atomic Force Microscope Tips
(2013-06-27)
Cheng, Hui-Wen
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Chang, Yuan-Chih
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Yuan, Chi-Tsu
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Tang, Song-Nien
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Chang, Chia-Seng
This paper introduces a simple, yet controllable scheme to pick up a single 13 nm Au nanoparticle (Au-NP) using the tip of an atomic force microscope (AFM) probe through the application of electrical biases between the tip and the Au-NP. Transmission electron microscope (TEM) images were acquired to verify that a single Au-NP was attached to the AFM probe. We postulate that the mechanism underlying the ability to manipulate individual Au-NPs at the apex of the AFM probe tip is Coulomb interaction induced by tip bias. The AFM tip with the attached Au-NP was then used to study the interaction between a single quantum dot (QD) and the Au-NP. The blinking behavior of single colloidal CdSe/ZnS core/shell QD was significantly suppressed with the approach of the 13 nm Au-NP attached to the AFM tip.
Size dependent magnetization and high-vacuum annealing enhanced ferromagnetism in Zn(1-x)Co(x)O nanowires
(2008-01-01)
Jian, Wen-Bin
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Chen, I-Jan
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Liao, Tai-Ching
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Ou, Yi-Ching
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Nien, Cheng-Hsun
Diameter controllable ZnO nanowires have been fabricated by thermal evaporation (vapor transport) with various sizes of gold nanoparticles as catalysts. Diluted magnetic semiconductor (DMS) Zn(1-x)Co(x)O nanowires were then made by high energy Co ion implantation. The as-implanted and the argon-annealed Zn(1-x)Co(x)O nanowires displayed weak ferromagnetism while the high-vacuum annealed nanowires exhibited strong ferromagnetic ordering at room temperature. Size dependent behavior has been observed in the magnetic field and temperature dependences of magnetization. The shrinkage of the nanowire diameter reduced the spontaneous magnetization as well as the hysteresis loops. Field cooled and zero-field cooled magnetization and coercivity measurements were performed between 2 and 300 K to study the evolution of magnetism from the weak to the strong ferromagnetic states. In particular, superparamagnetic features were observed and shown to be intrinsic characteristics of the DMS Zn(1-x)Co(x)O nanowires. The room-temperature spontaneous magnetization of individual Zn(1-x)Co(x)O nanowires was also established by using magnetic force microscope measurements.
Size effects on thermal treatments and room-temperature ferromagnetism in high-vacuum annealed ZnCoO nanowires
(2008-06-26)
Chen, I-Jan
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Ou, Yi-Ching
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Wu, Zhong-Yi
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Chen, Fu-Rong
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Kai, Ji-Jung
Zn0.92Co0.08O nanowires with two different average diameters, 19 and 38 nm, have been made by the vapor transport and Co ion implantation method. The as-implanted nanowires were thermally annealed through multiple steps in a high vacuum. The morphology and crystal structure of the nanowires were inspected by use of scanning and transmission electron microscopes. Electron microscopy analysis was used to ensure the absence of Co nanocrystals in the annealed nanowires. Measurements of temperature-dependent hysteresis were carried out to demonstrate a strong magnetic state in the high-vacuum annealed samples. The coercive field obeying a square-root temperature dependence and the room-temperature ferromagnetism have been discovered. Moreover, by comparison of magnetic properties between different-diameter nanowires, field-dependent magnetizations reveal considerably stronger ferromagnetism in the smaller diameter (19 nm) Zn0.92Co0.08O nanowires than that in the larger diameter (38 nm) nanowires. We argue that the generation of point defects by thermal annealing is the origin for the enhanced ferromagnetism in our high-vacuum annealed nanowires.
Synthesis of Apolipoprotein B Lipoparticles to Deliver Hydrophobic/Amphiphilic Materials
(2013-08-14)
Chu, Hsueh-Liang
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Cheng, Tsai-Mu
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Chen, Hung-Wei
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Chou, Fu-Hsuan
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Chang, Yu-Chuan
To develop a drug delivery system (DDS), it is critical to address challenging tasks such as the delivery of hydrophobic and amphiphilic compounds, cell uptake, and the metabolic fate of the drug delivery carrier. Low-density lipoprotein (LDL) has been acknowledged as the human serum transporter of natively abundant lipoparticles such as cholesterol, triacylglycerides, and lipids. Apolipoprotein B (apo B) is the only protein contained in LDL, and possesses a binding moiety for the LDL receptor that can be internalized and degraded naturally by the cell. Therefore, synthetic/reconstituting apoB lipoparticle (rABL) could be an excellent delivery carrier for hydrophobic or amphiphilic materials. Here, we synthesized rABL in vitro, using full-length apoB through a five-step solvent exchange method, and addressed its potential as a DDS. Our rABL exhibited good biocompatibility when evaluated with cytotoxicity and cell metabolic response assays, and was stable during storage in phosphate-buffered saline at 4 degrees C for several months. Furthermore, hydrophobic superparamagnetic iron oxide nanoparticles (SPIONPs) and the anticancer drug M4N (tetra-O-methyl nordihydroguaiaretic acid), used as an imaging enhancer and lipophilic drug model, respectively, were incorporated into the rABL, leading to the formation of SPIONPs- and M4N- containing rABL (SPIO@rABL and M4N@rABL, respectively). Fourier transform infrared spectroscopy suggested that rABL has a similar composition to that of LDL, and successfully incorporated SPIONPs or M4N. SPIO@rABL presented significant hepatic contrast enhancement in T-2-weighted magnetic resonance imaging in BALB/c mice, suggesting its potential application as a medical imaging contrast agent. M4N@rABL could reduce the viability of the cancer cell line A549. Interestingly, we developed solution-phase high-resolution transmission electron microscopy to observe both LDL and SPIO@rABL in the liquid state. In summary, our LDL-based DDS, rABL, has significant potential as a novel DDS for hydrophobic and amphiphilic materials, with good cell internalization properties and metabolicity.
Valence state map of iron oxide thin film obtained from electron spectroscopy imaging series
(2007)
Chen, Ko-Feng
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Lo, Shen-Chuan
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Chang, Li
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Egerton, Ray
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Kai, Ji-Jung
This paper demonstrates the applicability of electron-spectroscopic imaging (ESI) for valence-state mapping of the iron oxide system. We have previously developed a set of signal-processing methods for an EST series, to allow mapping Of sp(2)/sp(3) ratio, dielectric function and energy bandgap. In this study, these methods are applied to generate a valence-state map of an iron oxide thin film (Fe/alpha-Fe2O3). Two problems, data undersampling and a convolution effect associated with extraction of the image-spectrum from the core loss image series, were overcome by using cubic-polynomial interpolation and maximum-entropy deconvolution. As a result, the reconstructed image-spectrum obtained from the EST series images has a quality as good as that of conventional electron energy-loss spectra. The L-3/L-2 ratio of the reconstructed EST spectrum is determined to be 3.30 +/- 0.30 and 5.0 +/- 0.30 for Fe and alpha-Fe2O3, respectively. Our L-3/L-2, ratio mapping shows an accurate correspondence across the Cu/Fe/alpha-Fe2O3 region. The effect of delocalization and chromatic aberration on the EST resolution is discussed and estimated to be about 2 nm for the case of L-3/L-2, ratio mapping. (c) 2006 Published by Elsevier Ltd.