Kyeongwoon Chung

The valorization of Sargassum horneri, an abundant brown macroalga in East Asia, offers an opportunity to develop bioactive materials while addressing biomass-management challenges. In this study, S. horneri extract (SHE) was incorporated into electrospun polylactic acid (PLA) nanofiber sheets at 0, 0.2, 0.6, and 1.0%, denoted SHE0/PLA, SHE2/PLA, SHE6/PLA, and SHE10/PLA, respectively. SHE incorporation reduced the mean fiber diameter from 502.28 nm for SHE0/PLA to 355.64, 363.06, and 308.96 nm for SHE2/PLA, SHE6/PLA, and SHE10/PLA, respectively, while the tensile strength remained within a narrow range. SHE10/PLA exhibited 99.9% antibacterial activity against both Staphylococcus aureus and Klebsiella pneumoniae, and DPPH radical-scavenging activity increased with SHE content. The nanofiber-sheet extracts did not markedly reduce human fibroblast viability, and SHE6/PLA and SHE10/PLA promoted scratch closure to approximately 97.5% after 24 h. In a full-thickness wound model in Sprague-Dawley rats, SHE10/PLA showed the smallest residual wound area on day 14 and qualitatively enhanced re-epithelialization and collagen-rich tissue formation. These results indicate that SHE-loaded PLA nanofiber sheets combine antibacterial, antioxidant, and wound-healing-related functions and provide a potential route for the value-added utilization of S. horneri biomass.

Ultra-high-molecular-weight polyethylene membranes are promising materials for semiconductors, medical, and separation processes due to their high chemical resistance and mechanical robustness. However, their inherently low surface energy and chemical inertness impose substantial limitations on surface functionalization and water permeation. In this study, we propose a strategy to introduce an ethylenediaminetetraacetic acid chelating layer by integrating a hydrophilic interlayer formed through tannic acid–3-aminopropyltriethoxysilane coating with a photoacid-induced sol–gel reaction. This approach overcomes the constraints of conventional membranes and enables effective removal of trace metal ions. The optimized membrane (A10T50) exhibits a mean pore diameter of 81.4 nm and maintains a high water flux of 1881 L·m−2·h−1 while achieving approximately 95% Cu(II) removal, corresponding to an adsorption capacity of 1.4 × 10−4 meq·cm−2. Furthermore, the regenerated membranes consistently maintained more than 90% removal efficiency across multiple cycles, while preserving the average area-specific adsorption capacities of 4.39 × 10−4 meq·cm−2 (Al(III)), 2.15 × 10−4 meq·cm−2 (Ni(II)), 1.87 × 10−4 meq·cm−2 (Zn(II)), and 1.45 × 10−4 meq·cm−2 (Cu(II)). These findings demonstrate that photoacid-mediated silanization offers a controllable and scalable route to fabricate metal-ion-chelating ultra-high-molecular-weight polyethylene membranes suitable for ultrapure water polishing applications.

The detection of biologically relevant subtle mechanical forces, such as cellular traction forces (CTFs, ∼kPa), is critical for advancing cancer diagnostics and understanding mechanobiology. However, conventional mechanochromic molecules require high mechanochromic threshold stresses (∼GPa) for their fluorescence changes, restricting their applicability in biomedical applications. Here, we present an innovative class of mechanochromic molecules showing unprecedented mechanochromic threshold stress of 0.5 Pa. The mechanochromic molecules undergo a supercooled liquid‐to‐crystal transition with clear fluorescence deviation upon mechanical stimuli, while showing gradually controlled mechanochromic sensitivity. Our extremely sensitive mechanochromic devices effectively distinguish cancer cells having different CTF characteristics, correlating with their metastatic tendencies. Especially, patient‐derived cancer cells from primary tumors and metastatic sites exhibited distinct contrasts in fluorescence signal turn‐on rates of 18.7% and 73.5%, respectively, emphasizing this platform's potential for cancer diagnostics and therapeutic monitoring. This work represents a significant advance in mechanochromic materials technology, providing high‐sensitivity tools for various biomedical applications.

Metal-organic frameworks (MOFs) are advanced porous materials widely utilized in adsorption applications owing to their exceptionally high surface area. In this study, we report the fabrication of 3D-printed MOF-based scaffolds with enhanced water adsorption cycle stability by incorporating trimethylolpropane triacrylate (TMPTA). Furthermore, ligand exchanged MOF-801 with 2-carboxyethyl acrylate (CEA) resulted in a 15% increase in compressive strength of the 3D-printed scaffolds. This improvement is attributed to enhanced photopolymerization conversion and the formation of a robust cross-linked network between CEA and TMPTA. The CEA-functionalized MOF-801 scaffolds exhibited excellent cycling performance, maintaining consistent water adsorption over 10 consecutive cycles. These results highlight the potential of CEA-functionalized MOF architectures for use in adsorption, separation, and catalysis. By simultaneously enhancing mechanical robustness and structural stability, this approach offers a promising strategy for developing durable, high-performance MOF-based scaffolds for a wide range of practical applications.

Cellulose nanofibril (CNF)-based hydrogels, owing to their sustainability, biocompatibility, and versatile mechanical properties, are promising for biomedical applications. This review analyzes the recent advances and biomedical applications of CNF hydrogels. CNF hydrogels can be prepared via physical and chemical crosslinking. Physical crosslinking involves surface charge density control, pH manipulation, and flow-based processing to generate stable networks, whereas chemical crosslinking employs agents such as epichlorohydrin and citric acid to form permanent covalent bonds. These approaches enable precise control over hydrogel properties, including mechanical strength, porosity, and stimuli responsiveness. CNF hydrogels are particularly promising in drug delivery systems and tissue engineering. CNFs as drug delivery vehicles offer enhanced bioavailability and drug loading capacity owing to their open pore structure and large surface area. Recent developments in stimuli-responsive and injectable CNF hydrogels have enabled controlled drug release and improved targeting capabilities. Moreover, CNF hydrogels serve as effective scaffolds for cell growth and tissue regeneration, with applications in cartilage engineering and wound healing. Integrating CNF hydrogels with 3D bioprinting technology has generated complex tissue structures. However, several challenges remain, including the need for the standardization of toxicology assessments, optimization of large-scale production processes, and development of sophisticated control mechanisms for drug delivery. Future research should advance manufacturing technologies, improve long-term stability, and develop standardized testing protocols for regulatory compliance.

Cellulose nanofibril (CNF)-based hydrogels, owing to their sustainability, biocompatibility, and versatile mechanical properties, are promising for biomedical applications. This review analyzes the recent advances and biomedical applications of CNF hydrogels. CNF hydrogels can be prepared via physical and chemical crosslinking. Physical crosslinking involves surface charge density control, pH manipulation, and flow-based processing to generate stable networks, whereas chemical crosslinking employs agents such as metal ions, epichlorohydrin, and citric acid to form permanent covalent bonds. These approaches enable precise control over hydrogel properties, including mechanical strength, porosity, and stimuli-responsiveness. CNF hydrogels are particularly promising in drug delivery systems and tissue engineering. CNFs as drug delivery vehicles offer enhanced bioavailability and drug loading capacity owing to their open pore structure and large surface area. Recent developments in stimuli-responsive and injectable CNF hydrogels have enabled controlled drug release and improved targeting capabilities. Moreover, CNF hydrogels serve as effective scaffolds for cell growth and tissue regeneration, with applications in cartilage engineering and wound healing. Integrating CNF hydrogels with 3D bioprinting technology has generated complex tissue structures. However, several challenges remain, including the need for standardizing toxicology assessments, optimizing large-scale production processes, and developing sophisticated control mechanisms for drug delivery. Future research should advance manufacturing technologies, improve long-term stability, and develop standardized testing protocols for regulatory compliance.

Dielectric materials are highly desired for pulsed power capacitors due to their ultra-fast charge-discharge rate and excellent fatigue behavior. Nevertheless, the low energy storage density caused by the low breakdown strength has been the main challenge for practical applications. Herein, we report the electric energy storage properties of (1 − x) Bi_0.5(Na_0.8K_0.2)_0.5TiO₃-xBi_0.2Sr_0.7TiO₃ (BNKT-BST; x = 0.15–0.50) relaxor ferroelectric ceramics that are enhanced via a domain engineering method. A rhombohedral-tetragonal phase, the formation of highly dynamic PNRs, and a dense microstructure are confirmed from XRD, Raman vibrational spectra, and microscopic investigations. The relative dielectric permittivity (2664 at 1 kHz) and loss factor (0.058) were gradually improved with BST (x = 0.45). The incorporation of BST into BNKT can disturb the long-range ferroelectric order, lowering the dielectric maximum temperature T_m and inducing the formation of highly dynamic polar nano-regions. In addition, the T_m shifts toward a high temperature with frequency and a diffuse phase transition, indicating relaxor ferroelectric characteristics of BNKT-BST ceramics, which is confirmed by the modified Curie-Weiss law. The rhombohedral-tetragonal phase, fine grain size, and lowered T_m with relaxor properties synergistically contribute to a high P_max and low P_r, improving the breakdown strength with BST and resulting in a high recoverable energy density W_rec of 0.81 J/cm³ and a high energy efficiency η of 86.95% at 90 kV/cm for x = 0.45.