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594 results on '"Koh, Won-Gun"'

17. Occlusive membranes for guided regeneration of inflamed tissue defects

Author

Choi, Woojin, Mangal, Utkarsh, Park, Jin-Young, Kim, Ji-Yeong, Jun, Taesuk, Jung, Ju Won, Choi, Moonhyun, Jung, Sungwon, Lee, Milae, Na, Ji-Yeong, Ryu, Du Yeol, Kim, Jin Man, Kwon, Jae-Sung, Koh, Won-Gun, Lee, Sangmin, Hwang, Patrick T. J., Lee, Kee-Joon, Jung, Ui-Won, Cha, Jae-Kook, Choi, Sung-Hwan, and Hong, Jinkee

Published
2023
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26. Electrohydrodynamic Printing of Biodegradable PLGA Micro‐Patterns on 3D Polymer Structures.

Author

Seo, IlHo, Hassan, Rizwan Ul, Ryu, Byeongseok, Koh, Won‐Gun, and Ryu, WonHyoung

Abstract

Biodegradable polymers such as polylactic‐co‐glycolic acids (PLGA) are used for various implantable devices such as tissue scaffolds, drug delivery devices, and biosensors in different forms. However, high‐resolution patterning of biodegradable polymers on implantable devices has not been explored much yet. While electrohydrodynamic printing (EHD) can achieve high‐resolution printing compared to other printing methods, EHD printing of PLGA solutions is rarely attempted due to unstable printing. Such printing instability originates from the volatile nature of PLGA inks, and it causes nozzle clogging or change of ink conditions during printing. Here, PLGA ink formulation and a voltage input profile are studied for stable and high‐resolution EHD printing. Addition of glycerol at an optimal ratio as well as the control of voltage pulse shape strongly influenced both the stability and resolution of EHD printing of PLGA patterns. With the optimized inks and voltage inputs, stable printing of PLGA micropatterns down to 5 µm is achieved on both conductive and insulating surfaces for controlled drug release. Furthermore, use of a ring type electrode allows for EHD printing of PLGA micropatterns on 3D surfaces of PLLA tubes and stent struts. [ABSTRACT FROM AUTHOR]

Published
2024
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49. Fine‐Tunable CO2 Colorimetric Sensors and CO2 Level Indicator Meter with Horizontal Linear Gauge via Inter‐Chain Spacers.

Author

Kim, Donghyun, Hwang, Ki‐Seob, Koh, Won‐Gun, and Lee, Jun‐Young

Subjects
CARBON dioxide detectors, DETECTORS, CARBON dioxide, EUCLIDEAN distance, DETECTION limit, GAS detectors
Abstract

Fine‐tuning the sensing properties of carbon dioxide (CO2) colorimetric sensors is a challenging task. In this study, a short synthetic route is developed for CO2‐responsive nanoparticles with diverse sensitivity and detection range across a wide range of CO2 concentrations. This involves the addition of oily liquids as inter‐chain spacers, which changes the diffusivity of CO2 gas into the sensing matrices without other chemical modifications. R values and the limit of detection (LOD) are estimated from Euclidean distance (ED) curves, indicating a ten‐fold difference in sensitivity. Optical and physical analyses revealed that these results arise from intercalating inter‐chain spacers between polymeric chains and modifying the gas diffusivity. Furthermore, the sensitivity and detection range can be easily tuned by mixing two CO2‐responsive nanoparticles having different inter‐chain spacers, allowing the fabrication of the sensors with subtle differences in sensitivity and detection range. Based on these results, a CO2 level meter with a horizontal linear gauge that allows visible identification of the level of CO2 over the entire range of CO2 concentrations (from 0% to 100%) is developed. Consequently, the findings will be helpful in achieving a better understanding of gas information and finding an effective way to control the characteristics of colorimetric sensors. [ABSTRACT FROM AUTHOR]

Published
2024
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