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Kim, Taeho,Momin, Eric,Choi, Jonghoon,Yuan, Kristy,Zaidi, Hasan,Kim, Jaeyun,Park, Mihyun,Lee, Nohyun,McMahon, Michael T.,Quinones-Hinojosa, Alfredo,Bulte, Jeff W. M.,Hyeon, Taeghwan,Gilad, Assaf A. American Chemical Society 2011 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.133 No.9
<P/><P>Mesoporous silica-coated hollow manganese oxide (HMnO@mSiO<SUB>2</SUB>) nanoparticles were developed as a novel <I>T</I><SUB>1</SUB> magnetic resonance imaging (MRI) contrast agent. We hypothesized that the mesoporous structure of the nanoparticle shell enables optimal access of water molecules to the magnetic core, and consequently, an effective longitudinal (<I>R</I><SUB>1</SUB>) relaxation enhancement of water protons, which value was measured to be 0.99 (mM<SUP>−1</SUP>s<SUP>−1</SUP>) at 11.7 T. Adipose-derived mesenchymal stem cells (MSCs) were efficiently labeled using electroporation, with much shorter <I>T</I><SUB>1</SUB> values as compared to direct incubation without electroporation, which was also evidenced by signal enhancement on <I>T</I><SUB>1</SUB>-weighted MR images in vitro. Intracranial grafting of HMnO@mSiO<SUB>2</SUB>-labeled MSCs enabled serial MR monitoring of cell transplants over 14 days. These novel nanoparticles may extend the arsenal of currently available nanoparticle MR contrast agents by providing positive contrast on <I>T</I><SUB>1</SUB>-weighted images at high magnetic field strengths.</P>
Fabrication of Resistive Random Access Memory by Atomic Force Microscope Local Anodic Oxidation
Jeff T.H. Tsai,Chia-Yun Hsu,Chia-Hsiang Hsu 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2015 NANO Vol.10 No.2
The fabrication of gallium, zinc and nickel oxide nanodots for application of resistive random access memory (RRAM) was demonstrated using the atomic force microscopy (AFM) local anodic oxidation technique. Thin metal ¯lms were deposited on indium tin oxide conductive glass substrates. In the atmospheric environment, using AFM equipped with an Ag-coated probe can generate metal oxide nanodots locally on the metal films. These nanodots act as an insulator layer in a single unit cell of the RRAM. The voltage-biased method allows devices to reset from a lowresistance state (LRS) to a high-resistance state (HRS) at 0.9 V. These results show the ability of the AFM local anodic oxidation to produce 50 nm NiO nanodots on glass substrates for potentially high-density RRAMs. As we developed the characteristics of the structure, we found that a lateral NiO nanobelt RRAM performs very low power operation from such experimental manufacturing process. Using a current-biased method, the lateral device switches from a HRS to a LRS with a low writing voltage of 0.64 V.
GALLIUM NITRIDE NANOWIRES ENHANCED HIGH-EFFICIENCY COLD CATHODE FLUORESCENT LAMP
JEFF. T. H. TSAI,ZI-JIE LIAO 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2011 NANO Vol.6 No.5
We demonstrated a cold cathode fluorescent lamp that contains gallium nitride (GaN) nanowires at the electrode surfaces in a gas discharge light source to enhance the power efficiency of this luminance system. GaN in the nanowire structure has a high geometric aspect ratio, which makes it an ideal plasma ignition enhancer. The nanostructure enhancer not only improves a lower ignition voltage but also eliminates the use of mercury in the conventional cold cathode fluorescent lamp system. Due to high temperature of plasma, the GaN nanowires are partially dissociated to release the Ga ions into the lamp. Because the Ga ion has a large capture cross-section of electrons, it helps the lamp electrodes to maintain a high electric resistance. This could enhance the power efficiency and prevent the sputtering effect on the electrode to improve the lifetime of the lamp. This mercury-free approach also makes such cold cathode fluorescent lamp as an environment-friendly device.
Cho, Minseon,Xiao, Yi,Nie, Jeff,Stewart, Ron,Csordas, Andrew T,Oh, Seung Soo,Thomson, James A,Soh, H Tom National Academy of Sciences 2010 PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF Vol.107 No.35
<P>We describe the integration of microfluidic selection with high-throughput DNA sequencing technology for rapid and efficient discovery of nucleic acid aptamers. The Quantitative Selection of Aptamers through Sequencing method tracks the copy number and enrichment-fold of more than 10 million individual sequences through multiple selection rounds, enabling the identification of high-affinity aptamers without the need for the pool to fully converge to a small number of sequences. Importantly, this method allows the discrimination of sequences that arise from experimental biases rather than true high-affinity target binding. As a demonstration, we have identified aptamers that specifically bind to PDGF-BB protein with K(d) < 3 nM within 3 rounds. Furthermore, we show that the aptamers identified by Quantitative Selection of Aptamers through Sequencing have approximately 3-8-fold higher affinity and approximately 2-4-fold higher specificity relative to those discovered through conventional cloning methods. Given that many biocombinatorial libraries are encoded with nucleic acids, we extrapolate that our method may be extended to other types of libraries for a range of molecular functions.</P>
Molecular Imaging of CXCL12 Promoter-driven HSV1-TK Reporter Gene Expression
Lina Alon,Dara L. Kraitchman,Michael Schär,Angel Cortez,Nirbhay N. Yadav,Rebecca Krimins,Peter V. Johnston,Michael T. McMahon,Peter C. M. van Zijl,Sridhar Nimmagadda,Martin G. Pomper,Jeff W. M. Bulte 한국생물공학회 2018 Biotechnology and Bioprocess Engineering Vol.23 No.2
The C-X-C motif chemokine 12 (CXCL12, SDF1a) and its receptor, CXCR4, play a fundamental role in several biological processes, including hematopoiesis, cardiogenesis, cancer progression, and stem cell migration. Noninvasive monitoring of CXCL12 is highly desirable for optimizing strategies that combine mobilization of therapeutic cells to combat cancer or to assist in cardiac tissue repair after myocardial infarction. Here, we report on an MRI reporter gene system for directly monitoring CXCL12 expression in vivo. Glioma cells and human adipose-derived stem cells (hADSC) were transduced with the herpes simplex virus type-1-thymidine kinase (HSV1- tk) reporter gene expressed under the CXCL12 promoter. HSV1-tk expression resulted in accumulation of the PET tracer [125I]FIAU in vitro and in vivo and induced cell death after ganciclovir treatment. Furthermore, the results show that conditional expression of the reporter gene can be induced by hypoxia in transduced cells. Transduced hADSC were incubated with the CEST MRI probe 5-methyl-5, 6- dihydrothymidine (5-MDHT) and transplanted into swine heart. Transplanted cells were clearly visible on Chemical Exchange Saturation Transfer (CEST) MRI using a 3T clinical scanner. Therefore, we conclude that it is possible to image CXCL12 expression with MRI in a large animal model, opening up a possible route to clinical translation.
Majid S. Koozehchian,Amin Daneshfar,Ebrahim Fallah,Hamid Agha-alinejad,Mohammad Samadi,Mojtaba Kaviani,Maryam Kaveh B,Y. Peter Jung,Mozhgan Hassanzadeh Sablouei,Najmeh Moradi,Conrad P. Earnest,T. Jeff 한국운동영양학회 2018 Physical Activity and Nutrition (Phys Act Nutr) Vol.22 No.4
[Purpose] Studies of L-carnitine in healthy athletic populations have yielded equivocal results. Further scientific-based knowledge is needed to clarify the ability of L-carnitine to improve exercise capacity and expedite the recovery process by reducing oxidative stress. This study aimed to examine the 9-week effects of L-carnitine supplementation on exercise performance, anaerobic capacity, and exercise-induced oxidative stress markers in resistance-trained males. [Methods] In a double-blind, randomized, and placebo-controlled treatment, 23 men (age, 25±2y; weight, 81.2±8.31 kg; body fat, 17.1±5.9%) ingested either a placebo (2 g/d, n=11) or L-carnitine (2 g/d, n=12) for 9 weeks in conjunction with resistance training. Primary outcome measurements were analyzed at baseline and at weeks 3, 6, and 9. Participants underwent a similar resistance training (4 d/w, upper/lower body split) for a 9-week period. Two-way ANOVA with repeated measures was used for statistical analysis. [Results] There were significant increases in bench press lifting volume at wk-6 (146 kg, 95% CI 21.1, 272) and wk-9 (245 kg, 95% CI 127, 362) with L-carnitine. A similar trend was observed for leg press. In the L-carnitine group, at wk-9, there were significant increases in mean power (63.4 W, 95% CI 32.0, 94.8) and peak power (239 W, 95% CI 86.6, 392), reduction in post-exercise blood lactate levels (-1.60 mmol/L, 95% CI -2.44, -0.75) and beneficial changes in total antioxidant capacity (0.18 mmol/L, 95% CI 0.07, 0.28). [Conclusion] L-carnitine supplementation enhances exercise performance while attenuating blood lactate and oxidative stress responses to resistance training.