TY - JOUR A1 - Sauter, Tilman A1 - Kratz, Karl A1 - Heuchel, Matthias A1 - Lendlein, Andreas T1 - Fiber diameter as design parameter for tailoring the macroscopic shape-memory performance of electrospun meshes JF - Materials and design N2 - Fibrous shape-memory polymer (SMP) scaffolds were investigated considering the fiber as basic microstructural feature. By reduction of the fiber diameter in randomly oriented electrospun polyetherurethane (PEU) meshes from the micro-to the nano-scale, we observed changes in the molecular orientation within the fibers and its impact on the structural and shape-memory performance. It was assumed that a spatial restriction by reduction of the fiber diameter increases molecular orientation along the orientation of the fiber. The stress-strain relation of random PEU scaffolds is initially determined by the 3D arrangement of the fibers and thus is independent of the molecular orientation. Increasing the molecular orientation with decreasing single fiber diameter in scaffolds composed of randomly arranged fibers did not alter the initial stiffness and peak stress but strongly influenced the elongation at break and the stress increase above the Yield point. Reduction of the single fiber diameter also distinctly improved the shape-memory performance of the scaffolds. Fibers with nanoscale diameters (< 100 nm) possessed an almost complete shape recovery, high recovery stresses and fast relaxation kinetics, while the shape fixity was found to decrease with decreasing fiber diameter. Hence, the fiber diameter is a relevant design parameter for SMP. KW - Nanofiber KW - Shape-memory polymer KW - Electrospinning KW - Function by design KW - Molecular orientation Y1 - 2021 U6 - https://doi.org/10.1016/j.matdes.2021.109546 SN - 1873-4197 VL - 202 PB - Elsevier CY - Amsterdam [u.a.] ER - TY - JOUR A1 - Tuncaboylu, Deniz Ceylan A1 - Friess, Fabian A1 - Wischke, Christian A1 - Lendlein, Andreas T1 - A multifunctional multimaterial system for on-demand protein release JF - Journal of controlled release N2 - In order to provide best control of the regeneration process for each individual patient, the release of protein drugs administered during surgery may need to be timely adapted and/or delayed according to the progress of healing/regeneration. This study aims to establish a multifunctional implant system for a local on-demand release, which is applicable for various types of proteins. It was hypothesized that a tubular multimaterial container kit, which hosts the protein of interest as a solution or gel formulation, would enable on-demand release if equipped with the capacity of diameter reduction upon external stimulation. Using devices from poly(epsilon-caprolactone) networks, it could be demonstrated that a shape-memory effect activated by heat or NIR light enabled on-demand tube shrinkage. The decrease of diameter of these shape-memory tubes (SMT) allowed expelling the payload as demonstrated for several proteins including SDF-1 alpha, a therapeutically relevant chemotactic protein, to achieve e.g. continuous release with a triggered add-on dosing (open tube) or an on-demand onset of bolus or sustained release (sealed tube). Considering the clinical relevance of protein factors in (stem) cell attraction to lesions and the progress in monitoring biomarkers in body fluids, such on-demand release systems may be further explored e.g. in heart, nerve, or bone regeneration in the future. KW - Shape-memory polymer KW - On-demand release KW - Proteins KW - Poly(epsilon-caprolactone) networks KW - Near infrared light triggered shape-recovery Y1 - 2018 U6 - https://doi.org/10.1016/j.jconrel.2018.06.022 SN - 0168-3659 SN - 1873-4995 VL - 284 SP - 240 EP - 247 PB - Elsevier CY - Amsterdam ER -