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Toxicity of graphene nanoflakes evaluated by cell-based electrochemical impedance biosensing.
Yoon, Ok Ja,Kim, Insu,Sohn, Il Yung,Kieu, Truong Thuy,Lee, Nae-Eung John Wiley Sons 2014 Journal of biomedical materials research. Part A Vol.102 No.7
<P>Graphene nanoflake toxicity was analyzed using cell-based electrochemical impedance biosensing with interdigitated indium tin oxide (ITO) electrodes installed in a custom-built mini-incubator positioned on an inverted optical microscope. Sensing with electrochemical measurements from interdigitated ITO electrodes was highly linear (R(2)?=?0.93 and 0.96 for anodic peak current (Ipa) and cathodic peak current (Ipc), respectively). Size-dependent analysis of Graphene nanoflake toxicity was carried out in a mini-incubator system with cultured HeLa cells treated with Graphene nanoflakes having an average size of 80 or 30 nm for one day. Biological assays of cell proliferation and viability complemented electrochemical impedance measurements. The increased toxicity of smaller Graphene nanoflakes (30 nm) as measured by electrochemical impedance sensing and optical monitoring of treated cells was consistent with the biological assay results. Cell-based electrochemical impedance biosensing can be used to assess the toxicity of nanomaterials with different biomedical and environmental applications.</P>
Reduction in oxidative stress during cellular responses to chemically functionalised graphene
Yoon, Ok Ja,Jung, Chang Yong,Sohn, Il Yung,Son, Young Min,Hwang, Byeong-Ung,Kim, Il Jin,Lee, Nae-Eung The Royal Society of Chemistry 2014 Journal of Materials Chemistry B Vol.2 No.32
<P>The two-dimensional nanocarbon material graphene (Gr) has been extensively studied due to its many potential biomedical applications including regenerative medicine, drug delivery, bioimaging, and biosensing. The effects of nitrogen-functionalisation on chemically driven Gr (CDG) cellular responses were studied by investigating the generation of reactive oxygen species (ROS) and mitochondrial morphology as well as focal adhesion, shape, proliferation and viability of HeLa cells grown on functionalised CDG (f-CDG) films. The drop casting of CDG nanosheets formed thin CDG films and the formation of nitrogen groups on the f-CDG thin films was mediated by N2plasma treatment without the formation of observable surface defects. N-containing functional groups on the CDG thin films contributed to an increase in hydrophilicity. The proliferation and viability of HeLa cells grown on the f-CDG thin films were enhanced compared to those grown on CDG films alone and control samples. N-functionalisation of CDG thin films effectively reduced the ROS generated from cells on the f-CDG films. These results indicate that N2plasma treatment of CDG is very useful in improving biocompatibility for the bio-application of graphene materials.</P>
Cellular Oxidative Stress Response to Graphene Oxide Films Functionalized by NH<sub>3</sub> Plasma
Yoon, Ok Ja,Son, Young Min,Hwang, Byeong-Ung,Sohn, Il-Yung,Lee, Nae-Eung American Scientific Publishers 2017 Journal of Nanoscience and Nanotechnology Vol.17 No.11
<P>Functionalization of graphene oxide (GO) films was performed for the enhancement of bioaffinity by NH3 plasma treatment. Our results demonstrated that the damage free treatments caused a significant change in the surface charge states from negatively charged states with oxygen containing groups on the pristine GO to positively charged states with amine groups on the functionalized GO (f-GO) films. The effects of the conversion of the surface charge states of GO on bioaffinity and biocompatibility were investigated through studies of the reactive oxygen species (ROS) generation mitochondrial morphology and cell proliferation and viability during the growth of HeLa cells on GO and f-GO films. The proliferation and viability of HeLa cells on GO and f-GO films were enhanced compared to those of the control cells. Also the ROS generation on the f-GO (20s treatment) films compared to the other films was reduced. The different physicochemical properties of f-GO induced by plasma-chemical functionalization had a decisive influence on the ROS generation and the proliferation and viability of cells.</P>
Yoon, Hae-Jung,Lee, Min-Yung,Jhon, GiI-Ja Korean Society for Biochemistry and Molecular Biol 1997 Journal of biochemistry and molecular biology Vol.30 No.4
Interactions between ganglioside $G_{M3}$ and glucose transporter, GLUT1 were studied by measuring the effect of $G_{M3}$ on steady-state and time-resolved fluorescence of purified GLUT1 in synthetic lipids and on the 3-O-methylglucose uptake by human erythrocytes. The intrinsic tryptophan fluorescence showed a GLUT 1 emission maximum of 335 nm, and increased in the presence of $G_{M3}$ by 12% without shifting the emission maximum, The fluorescence lifetimes of intrinsic tryptophan on GLUT1 consisted of a long component of 7.8 ns and a short component of 2,3 ns and $G_{M3}$ increased both lifetime components. Lifetime components were quenched by acrylamide and KI. Acrylarnide-mduced quenching of long-lifetime components was partly recovered by $G_{M3}$ However. KI-induccd quenching of short- and long-lifetime components was not rescued by $G_{M3}$. The anisotropy of 1.6-diphenyl-1.3.5-hexatriene (DPH)-probed dimyristoylphosphatidylcholine (DMPC) model membrane was also increased with $G_{M3}$ incorporation, The transport rate of 3-O-methylglucose increased by 20% with $G_{M3}$ incorporation on the erythrocytes, Therefore, $G_{M3}$ altered the environment of lipid membrane and induced the conformational change of GLUT1.
Yoon, Hae Jung,Lee, Min Yung,Jhon, Gil Ja 생화학분자생물학회 2000 BMB Reports Vol.30 No.4
Interactions between gangtioside G_(M3) and glucose transporter. GLUTl were studied by measuring the effect of G_(M3) on steady-state and time-resolved fluorescence of purified GLUT1 in synthetic lipids and on the 3-O-methylglucose uptake by human erythrocytes. The intrinsic tryptophan fluorescence showed a GLUT 1 emission maximum of 335 nm, and increased in the presence of G_(M3) by 12% without shifting the emission maximum. The fluorescence lifetimes of intrinsic tryptophan on GLUT1 consisted of a long component of 7.8 ns and a short component of 2.3 ns and G_(M3) increased both lifetime components. Lifetime components were quenched by acrylamide and KI. Acrylamide-induced quenching of long-lifetime components was partly recovered by G_(M3). However, KI-induced quenching of short- and long-lifetime components was not rescued by G_(M3). The anisotropy of 1.6-diphenyl-1,3,5-hexatriene (DPH)-probed dimyristoylphosphatidylcholine (DMPC) model membrane was also increased with G_(M3) incorporation. The transport rate of 3-O-methylglucose increased by 20% with G_(M3) incorporation on the erythrocytes. Therefore. G_(M3) altered the environment of lipid membrane and induced the conformational change of GLUT1.
갑상선 유두암에서 혈중 호중구-림프구 비율의 임상적 의의
신영일(Yung il Shin),조자영(Ja Young Cho),이유미(Yu Mi Lee),성태연(Tae Yon Sung),윤종호(Jong Ho Yoon),정기욱(Ki Wook Chung),홍석준(Suck Joon Hong) 대한갑상선-내분비외과학회 2016 The Koreran journal of Endocrine Surgery Vol.16 No.2
Purpose: Neutrophil-to-lymphocyte ratio (NLR) is a marker of systemic inflammatory response, which is inexpensive, easily calculated, and known to show correlation with prognosis of cancer. The aim of this study was to evaluate the relationship between NLR and prognosis of papillary thyroid carcinoma. Methods: A total of 1,142 patients who underwent total thyroidectomy for papillary thyroid carcinoma between 1995∼2005 at Asan Medical Center were enrolled in this study. Patients were categorized according to two groups based on NLR and clinico-pathological variables and disease survival were compared between the two groups. Results: Median age of patients was 45.4 years, and the median follow-up period was 48 months. The cut-off value of NLR for prediction of disease-free survival (DFS) was 2. Comparison of DFS between two groups stratified by NLR (NLR ≤2, NLR>2) showed little statistical difference (P=0.48). After adjusting for risk (N stage), there was no significant difference according to N stage (N0: P=0.86, N1a: P=0.4, N1b: P=0.12). Conclusion: NLR did not show correlation with disease free survival of papillary thyroid carcinoma.