Fibers, Volume 12, Issue 6 (June 2024) – 3 articles

The integration of magnetic nanoparticles within fibrillar structures represents an interesting avenue for the remotely controlled release of therapeutic agents. This work presents a novel drug release platform based on electrospun magnetic fibers (EMFs) combining drugs, magnetic nanoparticles (MNPs) and mesoporous silica nanoparticles (MSNs) for controlled drug delivery via alternating magnetic fields (AMF). The platform was demonstrated to be versatile and effective for hydrophilic ketorolac (KET) and hydrophobic curcumin (CUR) encapsulation and the major response observed for AMF-triggered release was reached using drug-loaded MSNs within the fibers, providing fine control over drug release patterns. The EMFs exhibited excellent inductive heating capabilities, showing a temperature increase of ∆T up to 8 °C within a 5 min AMF pulse. The system is shown to be promising for applications like transdermal pain management, oncological drug delivery, tissue engineering, and wound healing, enabling precise control over drug release in both spatial and temporal dimensions. The findings of this study offer valuable insights into the development of the next generation of smart drug delivery systems, based in multifunctional materials that can be remotely regulated and potentially revolutionize the field of nanomedicine. Full article

This study investigates a novel approach in modeling the system limits of a braked, high-speed yarn-laying process with in situ impregnation. Special attention is paid to the investigation of the yarn spool overrun after the robot has come to a standstill. This phenomenon occurs at low yarn tensions in combination with high traversing speed and/or acceleration. The modeling of the yarn spool overrun is carried out using physical equations, taking into account the travel speed, acceleration of the robot, and braking force of the spool brake. Previous research has confirmed various operating points of the yarn-laying process, but a comprehensive and complete analysis of the system limits at different operating points and speeds up to 2 m/s is missing. The result of the study is a novel model that describes the system boundaries of the direct-yarn-placement. Furthermore, models for robot braking time, carbon spool diameter, and spool mass are developed. The proposed models have an $R^2$ > 0.9674. Regarding the system stability boundaries, the calculations reveal that, as acceleration rises, the minimum tension requirement also increases. The same trend is found for system velocity. At $a=12.5$%, a minimum tension of 16 N suffices, compared to 23 N and 32 N at $a=25$% and 50%, respectively. The impact on tension of quadrupling the speed outweighs that of acceleration, with tension increasing by factors of up to 22.5 and 2, respectively. Full article

Porous carbon fibers play a pivotal role in electrochemistry due to their unique structural and textural properties, offering a promising avenue for diverse applications ranging from energy storage to electrocatalysis. In this study, we investigate the intricate relationship between the electrochemical responses of porous carbon fibers synthesized using the Design of Experiments protocol and their textural properties, aiming to elucidate key insights for material design and optimization. Through comprehensive correlation analyses, we uncover notable associations between oxygen reduction reaction mass activities and capacitances measured at different polarization rates, highlighting the significance of pore accessibility in dictating electrochemical performance. While direct correlations with specific surface area and total pore volume for mass activities were not observed, our findings reveal significant trends regarding capacitance retention. Specifically, materials with an elevated specific surface area and total pore volume demonstrate enhanced capacitance retention, particularly under varying charging and discharging rates. These results underscore the importance of optimizing specific surface area and pore volume to maximize capacitive performance across diverse operating conditions. Our study provides valuable guidance for developing porous carbon fibers tailored for superior electrochemical performance in various applications. Full article