Publications by authors named "Euiyoung Jung"

9 Publications

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Metal Ion Releasing Gold Nanoparticles for Improving Therapeutic Efficiency of Tumor Targeted Photothermal Therapy.

Tissue Eng Regen Med 2021 Sep 24. Epub 2021 Sep 24.

School of Chemical Engineering, Sungkyunkwan University, 2066, Seobu-ro, Jangan-gu, Suwon, 16419, Republic of Korea.

Background: Owing to the tumor-targeted migration capacity of human mesenchymal stem cells (hMSCs), they have been combined with nanoparticles for photothermal therapy. However, the low viability of hMSCs following transplantation remains a problem. Here, we developed iron (Fe) ion-releasing gold (Au) nanoparticles (IIAuNPs) for advanced tumor-targeted photothermal therapy using hMSCs.

Methods: IIAuNPs were designed to undergo degradation under low pH conditions, such as the endosomal microenvironment, for Fe ion release in hMSCs. After evaluating the properties of IIAuNP, the IIAuNP concentration for treating hMSCs was optimized in terms of cytotoxicity. In vitro cell migration and antiapoptotic factor secretion were observed in hMSCs. Additionally, IIAuNPs-treated hMSCs were intravenously injected into tumor-bearing mice, and enhanced tumor targeting based on improved cell viability and cell migration was evaluated. Three days after the injection, the mice were irradiated with 660 nm laser to confirm the enhanced photothermal effect.

Results: In vitro studies revealed that treating hMSCs with an optimum concentration of IIAuNPs enhanced cell migration and anti-apoptotic gene expression through intracellular Fe ion delivery. The viability of hMSCs under hypoxic cell culture conditions that mimic the in vivo microenvironment was also improved when hMSCs were treated with IIAuNPs, compared to hMSCs without IIAuNPs treatment. IIAuNPs-treated hMSCs showed significantly enhanced tumor-targeting efficiency and subsequent photothermal effect compared to hMSCs without IIAuNP treatment.

Conclusion: Our results suggest that our metal-ion-releasing photothermal nanoparticles may provide a promising platform for future photothermal therapies and related applications.
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http://dx.doi.org/10.1007/s13770-021-00385-6DOI Listing
September 2021

Regulation of intracellular transition metal ion level with a pH-sensitive inorganic nanocluster to improve therapeutic angiogenesis by enriching conditioned medium retrieved from human adipose derived stem cells.

Nano Converg 2020 Oct 16;7(1):34. Epub 2020 Oct 16.

School of Chemical Engineering, Sungkyunkwan University, Suwon, 440-746, Republic of Korea.

Cell therapy based on human adipose derived stem cells (hADSCs) is a known potential therapeutic approach to induce angiogenesis in ischemic diseases. However, the therapeutic efficacy of direct hADSC injection is limited by a low cell viability and poor cell engraftment after administration. To improve the outcomes of this kind of approach, various types of nanoparticles have been utilized to improve the therapeutic efficacy of hADSC transplantation. Despite their advantages, the adverse effects of nanoparticles, such as genetic damage and potential oncogenesis based on non-degradable property of nanoparticles prohibit the application of nanoparticles toward the clinical applications. Herein, we designed a transition metal based inorganic nanocluster able of pH-selective degradation (ps-TNC), with the aim of enhancing an hADSC based treatment of mouse hindlimb ischemia. Our ps-TNC was designed to undergo degradation at low pH conditions, thus releasing metal ions only after endocytosis, in the endosome. To eliminate the limitations of both conventional hADSC injection and non-degradable property of nanoparticles, we have collected conditioned medium (CM) from the ps-TNC treated hADSCs and administrated it to the ischemic lesions. We found that intracellular increment of transition metal ion upregulated the hypoxia-inducible factor 1α, which can induce vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) expressions. Based on the molecular mechanism, the secretion of VEGF and bFGF by ps-TNC treated hADSCs showed a significant improvement compared to that of untreated cells. Injecting the CM collected from ps-TNC treated hADSCs into the mouse hindlimb ischemia model (ps-TNC-CM group) showed significantly improved angiogenesis in the lesions, with improved limb salvage and decreased muscle degeneration compared to the group injected with CM collected from normal hADSCs (CM group). This study suggests a novel strategy, combining a known angiogenesis molecular mechanism with both an improvement on conventional stem cell therapy and the circumvention of some limitations still present in modern approaches based on nanoparticles.
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http://dx.doi.org/10.1186/s40580-020-00244-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7567771PMC
October 2020

Endosome-triggered ion-releasing nanoparticles as therapeutics to enhance the angiogenic efficacy of human mesenchymal stem cells.

J Control Release 2020 08 23;324:586-597. Epub 2020 May 23.

School of Chemical Engineering, Sungkyunkwan University, Suwon 16419, Republic of Korea. Electronic address:

Here, we report that Fe ions delivered into human mesenchymal stem cells (hMSCs) by bioreducible metal nanoparticles (NPs) enhance their angiogenic and cell-homing efficacy by controlling ion-triggered intracellular reactive oxygen species (ROS) and improve cell migration, while reducing cytotoxicity. Endosome-triggered iron-ion-releasing nanoparticles (ETIN) were designed to be low-pH responsive to take advantage of the low-pH conditions (4-5) of endosomes for in situ iron-ion release. Due to the different redox potentials of Fe and Au, only Fe could be ionized and released from our novel ETIN, while Au remained intact after ETIN endocytosis. Treatment with an optimal amount of ETIN led to a mild increase in intracellular ROS levels in hMSCs, which enhanced the expression of HIF-1α, a key trigger for angiogenic growth factor secretion from hMSCs. Treatmetn of hMSCs with ETIN significantly enhanced the expression of angiogenesis- and lesion-targeting-related genes and proteins. Transplantation of ETIN-treated hMSCs significantly enhanced angiogenesis and tissue regeneration in a wound-closing mouse model compared with those in untreated mice and mice that underwent conventional hMSC transplantation.
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http://dx.doi.org/10.1016/j.jconrel.2020.05.038DOI Listing
August 2020

Facile Aqueous-Phase Synthesis of Bimetallic (AgPt, AgPd, and CuPt) and Trimetallic (AgCuPt) Nanoparticles.

Materials (Basel) 2020 Jan 7;13(2). Epub 2020 Jan 7.

Department of Chemical Engineering, College of Engineering, Kyung Hee University, Yongin 17104, Korea.

Multi-metallic nanoparticles continue to attract attention, due to their great potential in various applications. In this paper, we report a facile aqueous-phase synthesis for multi-metallic nanoparticles, including AgPt, AgPd, CuPt, and AgCuPt, by a co-reduction method within a short reaction time of 10 min. The atomic ratio of bimetallic nanoparticles was easily controlled by varying the ratio of each precursor. In addition, we found that AgCuPt trimetallic nanoparticles had a core-shell structure with an Ag core and CuPt shell.
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http://dx.doi.org/10.3390/ma13020254DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7013979PMC
January 2020

Synthesis of Sub 3 nm-Sized Uniform Magnetite Nanoparticles Using Reverse Micelle Method for Biomedical Application.

Materials (Basel) 2019 Nov 22;12(23). Epub 2019 Nov 22.

Department of Chemical Engineering, Kyung Hee University, Yongin 17104, Korea.

We report a synthetic method for small and uniform FeO (magnetite) nanoparticles under mild conditions. Spherical sub-3 nm-sized magnetite nanoparticles were prepared via reverse micelles composed of oleylamine, F127, xylene, and water for the reaction of iron(III) stearate with hydrazine at a reaction temperature of 90 °C in air atmosphere. These synthesized magnetite nanoparticles exhibited good size uniformity. By controlling experimental conditions, we could easily control both size and size uniformity of these magnetite nanoparticles. We further investigated whether FeO could be used in biomedical applications. Cytotoxicity of FeO was evaluated with human adipose-derived stem cells (hADSCs). Our results showed that the number of hADSCs did not significantly decrease when these cells were treated with FeO nanoparticles at a concentration of up to 9 μg/mL. Apoptotic activity and cell proliferation of hADSCs treated with FeO nanoparticles were similar to those of hADSCs without any treatment. This novel method could be used for synthesizing uniform and biocompatible FeO nanoparticles with further biomedical applications.
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http://dx.doi.org/10.3390/ma12233850DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6926741PMC
November 2019

Enhancing the Wound Healing Effect of Conditioned Medium Collected from Mesenchymal Stem Cells with High Passage Number Using Bioreducible Nanoparticles.

Int J Mol Sci 2019 Sep 28;20(19). Epub 2019 Sep 28.

School of Chemical Engineering, Sungkyunkwan University, Suwon 16419, Korea.

Injecting human mesenchymal stem cells (hMSCs) at wound sites is known to have a therapeutic effect; however, hMSCs have several limitations, such as low viability and poor engraftment after injection, as well as a potential risk of oncogenesis. The use of a conditioned medium (CM) was suggested as an alternative method for treating various wounds instead of direct hMSC administration. In addition to not having the adverse effects associated with hMSCs, a CM can be easily mass produced and can be stored for long-term, thereby making it useful for clinical applications. In general, a CM is collected from hMSCs with low passage number; whereas, the hMSCs with high passage number are usually discarded because of their low therapeutic efficacy as a result of reduced angiogenic factor secretion. Herein, we used a CM collected from high passage number (passage 12, P12) hMSCs treated with gold-iron nanoparticles (AuFe NPs). Our AuFe NPs were designed to release the iron ion intracellularly via endocytosis. Endosomes with low pH can dissolve iron from AuFe NPs, and thus, the intracellularly released iron ions up-regulate the hypoxia-inducible factor 1α and vascular endothelial growth factor (VEGF) expression. Through this mechanism, AuFe NPs improve the amount of VEGF expression from P12 hMSCs so that it is comparable to the amount of VEGF expression from low passage number (passage 6, P6), without treatment. Furthermore, we injected the CM retrieved from P12 MSCs treated with AuFe NPs in the mouse skin wound model (AuFe P12 group). AuFe P12 group revealed significantly enhanced angiogenesis in the mouse skin wound model compared to the high passage hMSC CM-injected group. Moreover, the result from the AuFe P12 group was similar to that of the low passage hMSC CM-injected group. Both the AuFe P12 group and low passage hMSC CM-injected group presented significantly enhanced re-epithelization, angiogenesis, and tissue remodeling compared to the high passage hMSC CM-injected group. This study reveals a new strategy for tissue regeneration based on CM injection without considering the high cell passage count.
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http://dx.doi.org/10.3390/ijms20194835DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6801963PMC
September 2019

Aqueous-phase synthesis of layered double hydroxide nanoplates as catalysts for the oxygen evolution reaction.

Dalton Trans 2018 Dec;47(48):17342-17348

Department of Chemical Engineering, College of Engineering, Kyung Hee University, Yongin, 17104, Korea.

Transition metal layered double hydroxide (LDH) nanomaterials have been considered as good catalytic materials for various applications; however, there has been a limit in the economic efficiency and convenience of the synthetic method. In this work, we report a facile aqueous-phase route to the synthesis of transition metal LDH nanoplates including Mn-Ni and Zn-Ni. Electrochemical characterization of the synthesized Mn-Ni LDHs with different intercalated halogen anions was carried out for the oxygen evolution reaction (OER) and a Tafel slope of about 80 mV per decade was obtained which is comparable to those of the previously reported LDH nanoplates.
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http://dx.doi.org/10.1039/c8dt03764gDOI Listing
December 2018

Investigation on the Nucleation Stage of Palladium Nanoparticles Using a Microfluidic Droplet Generator Integrated with In Situ Sol-Gel Quencher.

Small 2018 11 21;14(48):e1802851. Epub 2018 Oct 21.

Department of Chemical Engineering, College of Engineering, Kyung Hee University, 1732 Deogyeong-daero, Giheung-gu, Yongin-si, Gyeonggi-do, 17140, Republic of Korea.

The nanoparticle (NP) synthesis undergoes stepwise processes starting from the input metal ions: nucleation, coalescence, ripening, and growth. Considering the whole process is completed in a very short time, the conventional flask-scale method, which requires at least minutes, is not adequate to trace the mechanism of NP nucleation. In this study, a microfluidic droplet generator is developed, which is capable of in situ sol-gel polymerization for synthetic reaction quenching. As a model, palladium (Pd) NPs are synthesized within microdroplets, and the reaction time is controlled by tuning the length of the microchannel. In the microfluidic design, the outmost microchannel is incorporated, in which tetraethyl orthosilicate (TEOS) dissolved in ethanol is injected. The generated droplets are merged to the outmost flow under the variety of time interval (50 to 5,000 ms), so that the tens of milliseconds observation on NP nucleation is conducted via flash-like sol-gel quenching. Based on the result analysis, the seeds of Pd NPs have undergone slight size fluctuation and then a thermodynamically stable aggregation/coalescence step within 5 s before moving into the growth stage. This microfluidic platform permits the study of the fundamental and initial stage of the NP synthesis, which cannot be approached by the conventional methodology.
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http://dx.doi.org/10.1002/smll.201802851DOI Listing
November 2018

Studies on Catalytic Activity of Hydrogen Peroxide Generation according to Au Shell Thickness of Pd/Au Nanocubes.

ACS Appl Mater Interfaces 2018 Nov 26;10(44):38109-38116. Epub 2018 Oct 26.

Department of Chemical Engineering, College of Engineering , Kyung Hee University , Yongin 17140 , Korea.

The catalytic properties of materials are determined by their electronic structures, which are based on the arrangement of atoms. Using precise calculations, synthesis, analysis, and catalytic activity studies, we demonstrate that changing the lattice constant of a material can modify its electronic structure and therefore its catalytic activity. Pd/Au core/shell nanocubes with a thin Au shell thickness of 1 nm exhibit high HO production rates due to their improved oxygen binding energy (Δ E) and hydrogen binding energy (Δ E), as well as their reduced activation barriers for key reactions.
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http://dx.doi.org/10.1021/acsami.8b14166DOI Listing
November 2018
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