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Achromatic–chromatic colorimetric sensors for on–off type detection of analytes
Heo, Jun Hyuk,Cho, Hui Hun,Lee, Jin Woong,Lee, Jung Heon The Royal Society of Chemistry 2014 The Analyst Vol.139 No.24
<P>We report the development of achromatic colorimetric sensors; sensors changing their colors from achromatic black to other chromatic colors. An achromatic colorimetric sensor was prepared by mixing a general colorimetric indicator, whose color changes between chromatic colors, and a complementary colored dye with no reaction to the targeted analyte. As the color of an achromatic colorimetric sensor changes from black to a chromatic color, the color change could be much easily recognized than general colorimetric sensors with naked eyes. More importantly, the achromatic colorimetric sensors enable on–off type recognition of the presence of analytes, which have not been achieved from most colorimetric sensors. In addition, the color changes from some achromatic colorimetric sensors (achromatic Eriochrome Black T and achromatic Benedict's solution) could be recognized with naked eyes at much lower concentration ranges than normal chromatic colorimetric sensors. These results provide new opportunities in the use of colorimetric sensors for diverse applications, such as harsh industrial, environmental, and biological detection.</P> <P>Graphic Abstract</P><P>We developed a method to convert a general colorimetric sensor to an achromatic colorimetric sensor by introducing a complementary colored dye to the sensor, helping users to detect the presence of analytes at much lower concentration and recognize the existence of analytes instinctively. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c4an01645a'> </P>
Chemical effects of organo-silanized SiO<sub>2</sub> nanofillers on epoxy adhesives
Heo, Jun Hyuk,Lee, Jin Woong,Lee, Byoungsang,Cho, Hui Hun,Lim, Byungkwon,Lee, Jung Heon Elsevier 2017 Journal of industrial and engineering chemistry Vol.54 No.-
<P><B>Abstract</B></P> <P>Although thermal and mechanical effects of organo-silanized SiO<SUB>2</SUB> nanofillers (NFs) incorporated into epoxy resins have been actively studied by many researchers, their chemical properties have rarely been reported. In this work, we investigated the chemical effects of organo-silanized SiO<SUB>2</SUB> NFs on epoxy adhesives with (3-glycidoxypropyl) methyldiethoxysilane (GPTMS) and (3-aminopropyl) trimethoxysilane (APTMS)-functionalized SiO<SUB>2</SUB> NFs.</P> <P>After curing epoxy-functionalized NF (EPOXY-NF) with triethylenetetramine (TETA) hardener, we were able to verify chemical crosslinking of the TETA hardener on EPOXY-NF with X-ray photoelectron spectroscopy, vacuum Fourier-transform infrared spectroscopy, and zeta potential analysis. Similarly, we found that after curing amine-functionalized NF (NH<SUB>2</SUB>-NF) with bisphenol A diglycidyl ether (DGEBA) epoxy resin, the resin was chemically crosslinked on NH<SUB>2</SUB>-NF as well.</P> <P>Finally, when we evaluated adhesion properties of adhesives composed of DGEBA resin/NH<SUB>2</SUB>-NF and TETA hardener/EPOXY-NF on the basis of ASTM D3163, we observed improvements in the shear strength of 79 and 49%, respectively, in comparison with bare SiO<SUB>2</SUB> NF. This suggests that the chemical effects of organo-silanized SiO<SUB>2</SUB> NFs indeed contribute to the adhesion properties of adhesives.</P> <P><B>Graphical abstract</B></P> <P>The organo-silanized SiO<SUB>2</SUB> nanofillers can directly interact with major components of epoxy adhesives, resulting in improved adhesion properties.▪</P> <P>[DISPLAY OMISSION]</P>
Heo, Jun Hyuk,Cho, Hui Hun,Lee, Jung Heon The Royal Society of Chemistry 2014 The Analyst Vol.139 No.22
<P>We report the development of surfactant free-gold nanoparticle (AuNP)–DNA complexes that remained stable in solutions with extremely high ionic strength, using seawater as a model solution. Although the stability of AuNPs can be increased to a certain degree by functionalizing negatively charged DNA strands on their surfaces, they still have limited stability in highly concentrated salt solutions. However, we found that AuNPs functionalized with poly-T bases have exceptional stability in high ionic strength solutions. For example, AuNPs functionalized with a 5T spacer remained highly stable in seawater, with no color change and no red-shift in absorbance spectra for up to 9 days. Using this surprising property of poly-T spacers, we prepared highly stable AuNP–DNA complexes containing random sequences by introducing 5T spacers on the random sequenced DNA strand. The random sequenced AuNP–DNA complexes remained stable in seawater, several molar concentrations of monovalent metal ion solutions (6.1 M Na<SUP>+</SUP> or 4.8 M K<SUP>+</SUP>), and millimolar concentrations of diverse divalent metal ions. In addition, the highly stable AuNP–DNA complex maintained biological activity in seawater, which was demonstrated by complementary reaction and aptamer based biosensing. These results provide important insight into NP use for various applications under harsh biological and environmental conditions.</P> <P>Graphic Abstract</P><P>A AuNP–DNA complex highly stable in extremely high ionic strength media, such as seawater, was obtained by inserting a few thymine bases into the DNA strands. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c4an01271b'> </P>
Stability of a gold nanoparticle-DNA system in seawater.
Heo, Jun Hyuk,Kim, Kyung-Il,Lee, Min Hyung,Lee, Jung Heon American Scientific Publishers 2013 Journal of Nanoscience and Nanotechnology Vol.13 No.11
<P>We investigated the stability of gold nanoparticles (AuNPs) in seawater. The large amount of Na+, Mg2+, K+, and Ca2+ in seawater makes AuNPs unstable resulting in immediate aggregation. We found that AuNPs become much more stable when they were treated with polyethylene glycol (PEG, MW = 20, 000) before exposure to seawater. The AuNPs maintained stability up to 10 days when they were treated with 16.6% PEG 20000. The AuNP-DNA complex formed in the presence of 3.3% PEG 20000 maintained stability when exposed to seawater. We also demonstrated that the AuNP-DNA complexes can be redispersed after centrifugation and show sequence-specific aggregation in seawater. The results show that the both AuNPs and an AuNP-DNA system can be used in seawater and have the potential to be used to study marine systems.</P>
The Effect of Glucose and Glucose Transporter on Regulation of Lactation in Dairy Cow
Young-Tae Heo,Joung-Jun Park,Hyuk Song 한국동물번식학회 2015 Reproductive & developmental biology Vol.39 No.4
Glucose is universal and essential fuel of energy metabolism and in the synthesis pathways of all mammalian cells. Glucose is the one of the major precursors of lactose synthesis using glycolysis result in producing milk fat and protein. During the milk fat synthesis, lipoprotein lipase (LPL) and CD36 are required for glucose uptake. Various morecules such as acyl-CoA synthetase 1 (ACSL1) activity of acetyl-CoA synthetase 2 (ACSS2), ACACA, FASN AGPAT6, GPAM, LPIN1 are closely related with milk fat synthesis. Additionally, glucose plays a major role for synthesizing lactose. Activations of lactose synthesize enzymes such as membranebound enzyme, beta-1,4-galactosyl transferase (B4GALT), glucose-6-phosphate dehydrogenase (G6PD) are changed by concentration of glucose in blood resulting change of amount of lactose production. Glucose transporters are a wide group of membrane proteins that facilitate the transport of glucose over a plasma membrane. There are 2 types of glucose transporters which consisted facilitative glucose transporters (GLUT); and sodium-dependent transport, mediated by the Na+/glucose cotransporters (SGLT). Among them, GLUT1, GLUT8, GLUT12, SGLT1, SGLT2 are main glucose transporters which involved in mammary gland development and milk synthesis. However, more studies are required for revealing clear mechanism and function of other unknown genes and transporters. Therefore, understanding of the mechanisms of glucose usage and its regulation in mammary gland is very essential for enhancing the glucose utilization in the mammary gland and improving dairy productivity and efficiency.
Heo, Myeong-Gang,Byun, Jae-Hyuk,Kim, Jun,Choung, Se-Young Elsevier 2018 Journal of Functional Foods Vol.46 No.-
<P><B>Abstract</B></P> <P>To appraise the effects and involved mechanism of <I>Dendropanax morbifera</I> leaves extract (DLE) on diabetes and retinal degeneration, in this study, male C57BLKS/J-m+/db and five groups of db/db mice were treated with 0.5% CMC or metformin or three doses of DLE for 6 weeks. Administration of DLE stimulated AMP-activated protein kinase in the liver, skeletal muscle and adipose tissue, leading to the improvement of gene and protein expression related with insulin resistance and glucose homeostasis in db/db mice. Morphological changes and insulin depletion of pancreatic islets were also attenuated by treatment of DLE. Moreover, DLE treatment prevented the deterioration of retina by regulating not only the gene expression related with apoptosis and neovascularization, but also the level of activator protein-1 in retina. Therefore, DLE improves diabetic phenotype and retinal degeneration, suggesting that DLE could be a prospective agent for preventing diabetes and related eye complication.</P> <P><B>Highlights</B></P> <P> <UL> <LI> <I>Dendropanax morbifera</I> leaves extract (DLE) attenuated diabetic phenotype. </LI> <LI> DLE improved insulin resistance and glucose homeostasis by activating AMPK. </LI> <LI> DLE delayed the progression of diabetes induced retinal degeneration. </LI> <LI> DLE regulated retinal gene expression related with apoptosis and neovascularization. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>