We designed a hydrogel system that not only responds to disease-relevant pH conditions but also allows precise control over the network density and drug release via acid-catalyzed imine bond formation. By comparing drugs with and without amine functionalities (DOX vs α-MS) and evaluating the effect of an acid catalyst on cross-linking and drug diffusion, we provide mechanistic insights into the rational design of cellulose-based smart hydrogels. Drug release experiments revealed pH-dependent behavior with accelerated release under acidic conditions due to imine bond hydrolysis. The presence of an acid catalyst enhanced cross-linking between aldehyde-functionalized TEMPO-oxidized cellulose nanofibers (A-TOCNF) and glycol chitosan (GC), leading to a denser network and suppressing DOX release. SEM analysis showed that acid-catalyzed samples exhibited more compact fibrous structures, correlating with higher mechanical stability, as confirmed by AFM-based Young’s modulus measurements. WST-8 assays using Colon26 cells validated the biocompatibility of the drug-free hydrogel and the anticancer efficacy of DOX-loaded hydrogels. Overall, this hydrogel system demonstrates excellent potential as a biodegradable, site-specific drug delivery platform that is responsive to disease-associated pH conditions. Given that over 40% of therapeutic compounds contain amine groups, the platform offers broad applicability for targeted and sustained drug delivery.

Water-soluble Cu complexes offer diverse applications in the biomedical field as Cu is an essential trace element for many physiological functions, including the wound healing process. Controlled delivery of such bioactive Cu complexes to the target system is a promising approach in biomedical applications. Herein, water-soluble Cu(II)-Schiff base complex-incorporated PCL nanofiber composites (PCL@C-1%, PCL@C-3%, and PCL@C-5%) were fabricated by the electrospinning process using a green solvent, acetic acid. Physicochemical properties of the resultant composite nanofibers were investigated by FE-SEM, EDS, TEM, UV-vis, FT-IR, XRD, TGA, BET, and XPS analyses. The successful incorporation of the Cu(II) complex into the PCL nanofiber was confirmed. Water contact angle (WCA) values revealed the hydrophobic nature of the PCL-composite nanofibers, which is also quite beneficial in the wound-healing process as it can create a hydrophobic barrier to prevent extra fluid absorption. To our delight, the release behavior of Cu complexes from the composite nanofibers was found to be gradual, highly controlled, and long-term release (up to 40 days). In addition, the resultant PCL composites demonstrated excellent antibacterial activity against both Gram-positive and Gram-negative bacteria. Overall, these findings provide significant insights into these Cu complex-incorporated PCL nanofiber membranes as potential antibacterial and long-term wound dressings.

This study focused on manufacturing efficient automobile sound-absorbing materials through alkaline treatment and dimple processing of recycled polyethylene terephthalate (rPET) nonwoven fabric. The rPET nonwoven fabric was produced with a sound-absorbing material through compression molding. It was improved through the development of porous sound-absorbing materials through alkaline treatment and resonant sound-absorbing materials through dimple processing. As a result of morphological analysis, alkaline treatment showed that pore size and air permeability increased according to temperature and concentration increase conditions. On the other hand, dimple processing caused a decrease in air permeability and a decrease in pores due to yarn fusion, and as the dimple diameter increased, the sound-absorbing coefficient increased in the 5000 Hz band. Finally, it was judged that effective sound absorption performance would be improved through a simple process through alkaline treatment and dimple processing, and thus there would be applicability in various industrial fields.