https://scholarworks.unist.ac.kr/handle/201301/115 2026-04-17T06:46:08Z https://scholarworks.unist.ac.kr/handle/201301/91358 Title: Speckle-Engineered Upconversion Amplification in Nanoemulsion-Templated Hydrogel Microdomes Author(s): Ryu, Chaeyeong; Yoo, Byungcheon; Lee, Seunghun; Jeong, Hyungyo; Jeong, Sanggyun; Cho, Heesu; Oh, Jongwon; Baek, Dahye; Kim, Jongkyu; Lee, Yubin; Gu, Eunsu; Kim, Dong-Hwan; Park, Jung-Hoon; Lee, Jiseok Abstract: Hydrogel-based photonic systems integrating luminescent emitters offer promise as soft, reconfigurable optical platforms, yet most designs lack internal optical engineering to control light propagation and confinement. Here, we present a lithographically programmable softphotonic platform in which upconversion nanocrystals (UCNs) encapsulated within fluorocarbon nanoemulsion droplets are embedded in a poly(ethylene glycol) diacrylate (PEGDA) hydrogel microdome. Upon drying, strong refractive index contrast between the PEGDA matrix and fluorocarbon droplets creates a cooperative optical microenvironment that structures the near-infrared (NIR) excitation beam into a speckle-like field with localized hot spots while extending the photon dwell time within the microdome via internal reflection-based waveguiding. These effects yield a fully reversible, greater than sevenfold enhancement of upconversion luminescence—well beyond simple concentration or mechanical densification. This optical gain originates from multiple-scattering-assisted speckle excitation activated only in the contracted microdome state. Because UCNs are pumped by invisible NIR speckle illumination that rapidly varies in 3D across the microdome height, the incoherent sum of the photoluminescence manifests as a homogeneous filter-free visible brightness increase. The hydrogel microdomes, fabricated via a customized digital micromirror device (DMD)-based microlithography, enable high-resolution patterning of moisture-responsive displays, multicolor emission motifs, and reversible QR-code encryption, establishing a scalable route toward speckle-engineered soft photonic systems. 2026-03-31T15:00:00Z https://scholarworks.unist.ac.kr/handle/201301/91353 Title: Engineering of CoA-Acylating Butyraldehyde Dehydrogenase for Enhanced 1,3-Butanediol Production in Escherichia coli Author(s): Cho, Seunghyun; Islam, Tayyab; Islam, Sobia; Lee, Junhak; Jung, Sung Won; Park, Sunghoon Abstract: Microbial production of 1,3-butanediol (1,3-BDO) offers a renewable route to this versatile C-4 chemical. However, the low performance of CoA-acylating butyraldehyde dehydrogenase (Bld), which contains a catalytic cysteine, limits efficient production in recombinant Escherichia coli (E. coli). In this study, wild-type Clostridium saccharoperbutylacetonicum Bld and its variant Bld* were biochemically characterized and engineered to improve conversion of 3-hydroxybutyryl-CoA (3-HB-CoA) to 3-hydroxybutyraldehyde (3-HBA). Enzyme activity was strongly reduced by the product, 3-HBA, and this reduction was largely alleviated by added cysteine. To mitigate this interference, several noncatalytic cysteine residues in Bld* were substituted individually and in combination guided by multiple sequence alignment and machine-learning-based mutational prediction. The triple mutant C151N/C189A/C353L (designated CYS31) displayed similar to 30% higher specific activity without altering substrate affinity or selectivity. Incorporation of CYS31 into a 1,3-BDO-producing E. coli strain led to a corresponding similar to 30% increase in titer, indicating that enhanced in vitro kinetics translated to higher in vivo 1,3-BDO production. These findings provide a more effective Bld variant for 1,3-BDO production and demonstrate that non-active-site cysteine residues can be viable engineering targets when an aldehyde intermediate is involved. 2026-02-28T15:00:00Z https://scholarworks.unist.ac.kr/handle/201301/91345 Title: Directional Anchoring Doping Networks for Robust Polymeric Bioelectronics Author(s): Yue, Yaru; Liang, Tianbiao; Yao, Canglang; Tang, Jihe; Li, Feng; Huo, Yao; Wang, Ducai; Liu, Peiji; Yang, Sangjin; Fan, Xin; Lin, Xiaoxue; Wang, Dong; Sun, Kuan; Yang, Changduk; Cao, Huajun; Chen, Shanshan Abstract: The development of conductive polymers that simultaneously achieve high electrical conductivity and tissue-like stretchability represents a persistent challenge in bioelectronics. Here, we demonstrate an "anchoring-buffering" molecular design strategy that overcomes this limitation through rationally designed in situ polymerizable hydroxyalkyl acrylate (HAX) dopants in poly(3,4-ethylenedioxythiophene): polystyrene sulfonate (PEDOT: PSS). Our dopant architecture features rigid acrylate groups that are inferred to maintain conjugation pathways by preferentially interacting with less conjugated PEDOT regions, and hydroxyl-terminated alkyl spacers that form a dynamic hydrogen-bond network for strain dissipation. By systematically varying alkyl chain lengths (HA0 to HA4), we optimize electrostatic screening to improve doping efficiency and pi-stacking order, achieving a composite film with exceptional performance (850 S/cm conductivity and 88% elongation) that surpasses existing stretchable conductive polymers. When integrated into conformal biointerfaces, the electrode maintains stable electrophysiological signal acquisition (EMG/ECG/EEG) with 99.5% gesture recognition accuracy after 24 h of continuous wear, establishing a general molecular design framework to decouple conductivity and stretchability for next-generation wearable and implantable electronics. 2026-02-28T15:00:00Z https://scholarworks.unist.ac.kr/handle/201301/91335 Title: Commercial-scale glycerol valorization using surface-modified copper cobalt oxide catalyst in high-capacity anion exchange membrane electrolyzer Author(s): Yoon, Ki-Yong; Hwang, Seon Woo; Roh, Hee Yoon; Gu, Jiwon; Lee, Kyung-Bok; Jeong, Jaehoon; Oh, Dongrak; Kwak, Myung-Jun; Yu, Je Min; Kim, Dohyung; Lee, Ji-Hoon; Choi, Sung Mook; Lim, Hankwon; Lee, Hosik; Jang, Ji-Wook; Yang, Juchan Abstract: Interest in electrochemical glycerol oxidation reactions (GORs) continues to grow as a promising strategy for hydrogen production. By replacing the oxygen evolution reaction (OER), GOR reduces energy consumption while generating hydrogen at the cathode and value-added formate at the anode, offering techno-economic advantages over conventional water electrolysis. However, its practical implementation is still hindered by reliance on precious metal catalysts and performance losses in scaled-up systems. Here, we synthesized a non-precious CuCo oxide (CCO) electrocatalyst at a tens-of-grams scale through co-precipitation and simple surface treatment. When applied to an anion exchange membrane (AEM) electrolyzer, the modified CuCo oxide achieved 110 mA cm-2 at 1.31 Vcell using a 7 cm2 non-precious GOR anode with 96% formate selectivity. The system was further scaled to a 79 cm2 anode, delivering 3.2 A at 1.31 Vcell. This study demonstrates a practical and economically favorable pathway for scalable hydrogen production via glycerol valorization in AEM electrolyzers. 2026-02-28T15:00:00Z