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Lee, Hyemi,Kim, Saehee,Choi, Bo-Hwa,Park, Moon-Taek,Lee, Jeonghun,Jeong, Seong-Yun,Choi, Eun Kyung,Lim, Byung-Uk,Kim, Chulhee,Park, Heon Joo Informa UK, Ltd. 2011 International journal of hyperthermia Vol.27 No.7
<P><I>Purpose:</I> We investigated the use of hyperthermia to improve the anti-cancer efficacy of doxorubicin (DOX)-loaded mesoporous silica nanocontainer Si-SS-CD-PEG. The hypothesis was that heat stimulates glutathione-mediated degradation of cyclodextrin gatekeeper, thereby causing the release of DOX from the carrier and DOX-induced cell death.</P><P><I>Materials and methods:</I> The release of DOX from DOX-loaded Si-SS-CD-PEG suspended in PBS containing glutathione (GSH) was studied by assessing the changes in DOX fluorescence intensity. The effect of heating at 42°C on the release of DOX from the intracellular carriers was determined with confocal microscopy. The extents of clonogenic and apoptotic cell death caused by DOX-loaded Si-SS-CD-PEG were determined.</P><P><I>Results:</I> The release of DOX from DOX-loaded Si-SS-CD-PEG in PBS occurred only when GSH presented in the suspension, and heating at 42°C slightly increased the release of DOX from the carriers. Heating significantly elevated the GSH content in A549 cells and increased the release of DOX from the internalised carriers. Heating the cancer cells treated with the carriers at 42°C markedly increased the clonogenic death and apoptosis. The GSH content in A549 cells was greater than that in L-132 cells, and A549 cells were far more sensitive than L-132 cells to DOX-loaded Si-SS-CD-PEG at both 37°C and 42°C.</P><P><I>Conclusions:</I> Hyperthermia increased the GSH-mediated release of DOX from DOX-loaded Si-SS-CD-PEG. Furthermore, hyperthermia markedly elevated the GSH content in cancer cells, thereby increasing the release of DOX from the internalised carriers and potentiating the DOX-induced clonogenic and apoptotic cell death.</P>
Saehee LEE,Amith ABRAHAM,Alan CHRISTIAN S. LIM,Okkyoung CHOI,Jeong Gil SEO,Byoung-In SANG 한국생물공학회 2021 한국생물공학회 학술대회 Vol.2021 No.10
Bacterial nanocellulose (BNC), a value-added biomaterial, has attracted attentions as an ideal precursor for nanostructured energy storage materials due to its fascinating features such as high purity, high crystallinity, and mechanical properties. However, the cost of BNC production is a challenge for its industrial applications. The present study used crude glycerol from the biodiesel industry as a carbon source for BNC production with Komagataeibacter sucrofermentans, and higher BNC production was observed in crude glycerol medium than glucose and pure glycerol media. BNC from crude glycerol medium showed a density of 0.92 g cm<SUP>-3</SUP> and a porosity of 38.6% as well as high crystallinity index (85%) and tensile strength (110 ㎫). The derived carbon materials by carbonization of BNC demonstrated highly porous structures and were evaluated for the supercapacitor application. This study showed the valorization of waste resources from the biodiesel industry to bio-nanomaterial and the potential of derived carbon as electrode materials for energy storage applications.
Lim, Saehee,Lee, Meehye,Czimczik, Claudia I.,Joo, Taekyu,Holden, Sandra,Mouteva, Gergana,Santos, Guaciara M.,Xu, Xiaomei,Walker, Jennifer,Kim, Saewung,Kim, Hyun Seok,Kim, Soyoung,Lee, Sanguk Elsevier 2019 Science of the Total Environment Vol.655 No.-
<P><B>Abstract</B></P> <P>Isotopes are essential tools to apportion major sources of aerosols. We measured the radiocarbon, stable carbon, and stable nitrogen isotopic composition of PM<SUB>2.5</SUB> at Taehwa Research Forest (TRF) near Seoul Metropolitan Area (SMA) during August–October 2014. PM<SUB>2.5</SUB>, TC, and TN concentrations were 19.4 ± 10.1 μg m<SUP>−3</SUP>, 2.6 ± 0.8 μg C m<SUP>−3</SUP>, and 1.4 ± 1.4 μg N m<SUP>−3</SUP>, respectively. The δ<SUP>13</SUP>C of TC and the δ<SUP>15</SUP>N of TN were − 25.4 ± 0.7‰ and 14.6 ± 3.8‰, respectively. EC was dominated by fossil-fuel sources with F<SUB>ff</SUB> (EC) of 78 ± 7%. In contrast, contemporary sources were dominant for TC with F<SUB>c</SUB> (TC) of 76 ± 7%, revealing the significant contribution of contemporary sources to OC during the growing season. The isotopic signature carries more detailed information on sources depending on air mass trajectories. The urban influence was dominant under stagnant condition, which was in reasonable agreement with the estimated δ<SUP>15</SUP>N of NH<SUB>4</SUB> <SUP>+</SUP>. The low δ<SUP>15</SUP>N (7.0 ± 0.2‰) with high TN concentration was apparent in air masses from Shandong province, indicating fossil fuel combustion as major emission source. In contrast, the high δ<SUP>15</SUP>N (16.1 ± 3.2‰) with enhanced TC/TN ratio reveals the impact of biomass burning in the air transported from the far eastern border region of China and Russia. Our findings highlight that the multi-isotopic composition is a useful tool to identify emission sources and to trace regional sources of carbonaceous and nitrogen aerosols.</P> <P><B>Highlights</B></P> <P> <UL> <LI> For PM<SUB>2.5</SUB>, the average δ<SUP>13</SUP>C of TC and δ<SUP>15</SUP>N of TN were −25.4 ± 0.7‰ and 14.6 ± 3.8‰respectively. </LI> <LI> EC and TC were dominated by fossil-fuel (78 ± 7%) and contemporary (76 ± 7%) sources, respectively. </LI> <LI> Low δ<SUP>15</SUP>N (7.0 ± 0.2‰) with high TN concentration was evident in air masses from Shandong province. </LI> <LI> Multi-isotopic composition is useful to trace regional sources of PM<SUB>2.5</SUB> aerosol. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>δ<SUP>13</SUP>C of TC versus f<SUB>M</SUB> (EC) for different levels of δ<SUP>15</SUP>N of TN observed at Taehwa Research Forest (TRF) and Gosan Climate Observatory (GCO). TRF samples were classified into groups according to air mass origin.</P> <P>[DISPLAY OMISSION]</P>
Saehee Lim,Meehye Lee,PaoloLaj,Sang-Woo Kim,Kang-Ho Ahn,Junsoo Gil,Xiaona Shanga,Marco Zanatta,Kyeong-Sik Kang 한국대기환경학회 2021 한국대기환경학회 학술대회논문집 Vol.2021 No.10
Over the past few decades, northeast Asia has suffered from the extreme levels of PM2.5. Despite extensive efforts and the scientific advances in understanding PM2.5 pollution, the fundamental mechanisms responsible for the occurrence of high PM2.5 concentrations have not been comprehensively understood. In this study, we investigated the physical and chemical drivers for the formation and transformation of atmospheric particles using a four-year dataset of nanoparticle number size distributions, PM2.5 chemical composition, gaseous precursors, and meteorological variables in nor theast Asia outflows. The empirical orthogonal function (EOF) analyses of size-separated particle numbers extracted two modes representing a burst of nanoparticles (EOF1) and an increase in PM2.5 mass (EOF2) associated with persistent anticyclone and synoptic-scale stagnation, respectively. The vertical structure of the particles demonstrated that the synoptic conditions also affected the daily evolution of boundary layer, promoting either the formation of nanoparticles through deep mixing or conversion into accumulation-mode particles in shallow mixed layers. In the haze-development episode equivalent to EOF2 during the KORUS-AQ (KORea-US Air Quality) campaign, the PM2.5 mass reached 63 mg m<SUP>-3</SUP> with the highest contribution from inorganic constituents, which was accompanied by a thick coating of refractory black carbon (rBC) that linearly increased with condensation-mode particles. This observational evidence suggests that the thick coating of rBC resulted from an active conversion of condensable gases into particle-phase on the BC surface, thereby increasing the mass of the accumulation-mode aerosol. Consequently, this result complies with the strategy to reduce black carbon as a way to effectively mitigate haze pollution as well as climate change in northeast Asia.
Lim, Saehee,Lee, Meehye,Rhee, Tae Siek Elsevier 2019 Science of the Total Environment Vol.668 No.-
<P><B>Abstract</B></P> <P>The water-soluble ions and carbonaceous compounds of PM<SUB>1</SUB> were measured at the King Sejong Station (KSG) in the northern part of Antarctic Peninsula from March to November in 2009. As the sum of all measured species including organic matter [OM; organic carbon (OC)*1.9], the PM<SUB>1</SUB> mass reached a maximum of 936 ng m<SUP>−3</SUP> with the mean of 686 ± 226 ng m<SUP>−3</SUP>. The most abundant constituents were OM (389 ± 109 ng m<SUP>−3</SUP>) and sea-salts (Na<SUP>+</SUP> and Cl<SUP>−</SUP>, 193 ± 122 ng m<SUP>−3</SUP>), which comprised 85% of the PM<SUB>1</SUB> mass. In contrast, the contribution of SO<SUB>4</SUB> <SUP>2−</SUP> was below 1% and its depletion relative to Na<SUP>+</SUP> was prevalent particularly during winter, which was attributed to the frost flowers on newly formed sea-ice surface. The OC concentration was the highest in fall and its subcomponents OC2 and OC3 were moderately correlated with sea-salts (<I>r</I> = 0.5), indicating the marine biogenic source for OC. The elemental carbon (EC) concentration was much lower than OC, leading to the mean OC/EC ratio over 10. While the charred fraction of EC (EC1) was elevated by the long-range transport of biomass burning plume from nearby continent, the mass fraction of soot-EC (EC23) was increased concurrently with enhanced NO<SUB>3</SUB> <SUP>−</SUP>, suggesting EC23 as a good indicator for local influence in pristine environments like Antarctic region.</P> <P><B>Highlights</B></P> <P> <UL> <LI> OM and sea-salts comprised 85% of the PM<SUB>1</SUB> (686 ± 226 ng m<SUP>−3</SUP>) at the KSG. </LI> <LI> The OC/EC ratio was greater than 10 with biogenic source for OC from the ocean. </LI> <LI> Char-EC was enhanced in biomass burning-impacted air from nearby continent. </LI> <LI> Soot-EC is a good tracer indicating local influence in Antarctic environment. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>