TY - JOUR A1 - Friess, Fabian A1 - Lendlein, Andreas A1 - Wischke, Christian T1 - Size control of shape switchable micronetworks by fast two-step microfluidic templating JF - Journal of materials research N2 - Shape-memory polymer micronetworks (MN) are micrometer-sized objects that can switch their outer shape upon external command.This study aims to scale MN sizes to the low micrometer range at very narrow size distributions. In a two-step microfluidic strategy, the specific design of coaxial class capillary devices allowed stabilizing the thread of the dispersed phase to efficiently produce precursor particles in the tip-streaming regime at rates up to similar to 170 kHz and final sizes down to 4 mu m. In a subsequent melt-based microfluidic photocrosslinking of the methacrylate-functionalized oligo(epsilon-caprolactone) precursor material, MN could be produced without particle aggregation. A comprehensive analysis of MN properties illustrated successful crosslinking, semi-crystalline morphology, and a shape-switching functionality for all investigated MN sizes (4, 6, 9, 12, 22 mu m). Such functional micronetworks tailored to and below the dimension of cells can enable future applications in technology and medicine like controlling cell interaction. Y1 - 2021 U6 - https://doi.org/10.1557/s43578-021-00295-2 SN - 0884-2914 SN - 2044-5326 VL - 36 IS - 16 SP - 3248 EP - 3257 PB - Springer CY - Berlin ER - TY - JOUR A1 - Friess, Fabian A1 - Roch, Toralf A1 - Seifert, Barbara A1 - Lendlein, Andreas A1 - Wischke, Christian T1 - Phagocytosis of spherical and ellipsoidal micronetwork colloids from crosslinked poly(epsilon-caprolactone) JF - International Journal of Pharmaceutics N2 - The effect of non-spherical particle shapes on cellular uptake has been reported as a general design parameter to control cellular recognition of particulate drug carriers. Beside shape, also size and cell-particle ratio should mutually effect phagocytosis. Here, the capability to control cellular uptake of poly(epsilon-caprolactone) (PCL) based polymer micronetwork colloids (MNC), a carrier system that can be transferred to various shapes, is explored in vitro at test conditions allowing multiple cell-particle contacts. PCL-based MNC were synthesized as spheres with a diameter of similar to 6, similar to 10, and 13 mu m, loaded with a fluorescent dye by a specific technique of swelling, redispersion and drying, and transferred into different ellipsoidal shapes by a phantom stretching method. The boundaries of MNC deformability to prolate ellipsoid target shapes were systematically analyzed and found to be at an aspect ratio AR of similar to 4 as obtained by a phantom elongation epsilon(ph) of similar to 150%. Uptake studies with a murine macrophages cell line showed shape dependency of phagocytosis for selected conditions when varying particle sizes (similar to 6 and 10 mu m),and shapes (epsilon(ph): 0, 75 or 150%), cell-particle ratios (1:1, 1:2, 1:10, 1:50), and time points (1-24 h). For larger-sized MNC, there was no significant shape effect on phagocytosis as these particles may associate with more than one cell, thus increasing the possibility of phagocytosis by any of these cells. Accordingly, controlling shape effects on phagocytosis for carriers made from degradable polymers relevant for medical applications requires considering further parameters besides shape, such as kinetic aspects of the exposure and uptake by cells. KW - Particle shape KW - Phagocytosis KW - Macrophage KW - Polymer micronetwork colloids KW - Poly(epsilon-caprolactone) Y1 - 2019 U6 - https://doi.org/10.1016/j.ijpharm.2019.118461 SN - 0378-5173 SN - 1873-3476 VL - 567 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Friess, Fabian A1 - Wischke, Christian A1 - Lendlein, Andreas T1 - Microscopic analysis of shape-shiftable oligo(epsilon-caprolactone)-based particles JF - MRS advances N2 - Spherical particles are routinely monitored and described by hydrodynamic diameters determined, e.g., by light scattering techniques. Non-spherical particles such as prolate ellipsoids require alternative techniques to characterize particle size as well as particle shape. In this study, oligo(epsilon-caprolactone) (oCL) based micronetwork (MN) particles with a shape-shifting function based on their shape-memory capability were programmed from spherical to prolate ellipsoidal shape aided by incorporation and stretching in a water-soluble phantom matrix. By applying light microscopy with automated contour detection and aspect ratio analysis, differences in characteristic aspect ratio distributions of non-crosslinked microparticles (MPs) and crosslinked MNs were detected when the degrees of phantom elongation (30-290%) are increased. The thermally induced shape recovery of programmed MNs starts in the body rather than from the tips of ellipsoids, which may be explained based on local differences in micronetwork deformation. By this approach, fascinating intermediate particle shapes with round bodies and two opposite sharp tips can be obtained, which could be of interest, e.g., in valves or other technical devices, in which the tips allow to temporarily encage the switchable particle in the desired position. KW - biomaterial KW - particulate KW - shape memory KW - responsive Y1 - 2019 U6 - https://doi.org/10.1557/adv.2019.392 SN - 2059-8521 VL - 4 IS - 59-60 SP - 3199 EP - 3206 PB - Cambridge Univ. Press CY - New York 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 - TY - JOUR A1 - Friess, Fabian A1 - Lendlein, Andreas A1 - Wischke, Christian T1 - Photoinduced synthesis of polyester networks from methacrylate functionalized precursors: analysis of side reactions JF - Polymers for advanced technologies N2 - Polyester networks can be prepared by ultraviolet (UV)-light-induced radical polymerization of methacrylate functionalized oligo(epsilon-caprolactone)s. The properties and functions of the obtained materials depend on defined network structures and may be altered, if crosslinking would occur by side reactions in other positions than the methacrylate endgroups. In order to explore whether and to which extent such side reactions occur, network synthesis as well as related model reactions were performed in the absence of photoinitiator. Hereby precursor structures (linear and four-arm star-shaped) and reaction conditions (in solution and in the melt) were varied. Unspecific side reactions were found only upon extensive UV irradiation for 60min (26 mW cm(-2)) with minor but detectable alterations of physicochemical properties of the networks. The analysis of model reactions suggested minor photolytic cleavage of ester bonds during polymer network synthesis. However, the effect of these side reactions on network properties and functions appeared to be less relevant than an incomplete precursor integration because of a too short UV irradiation for crosslinking. Copyright (c) 2014 John Wiley & Sons, Ltd. KW - poly(epsilon-caprolactone) methacrylate KW - crosslinking KW - excimer UV light KW - side reaction KW - photoinduced radical polymerization Y1 - 2014 U6 - https://doi.org/10.1002/pat.3313 SN - 1042-7147 SN - 1099-1581 VL - 25 IS - 11 SP - 1285 EP - 1292 PB - Wiley-Blackwell CY - Hoboken ER - TY - CHAP A1 - Friess, Fabian A1 - Lendlein, Andreas A1 - Wischke, Christian T1 - Investigating side-reactions during UV-induced preparation of oligo(epsilon-caprolactone) based shape-memory polymer networks T2 - Abstracts of papers : joint conference / The Chemical Institute of Cananda, CIC, American Chemical Society, ACS Y1 - 2013 SN - 0065-7727 VL - 245 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Friess, Fabian A1 - Wischke, Christian A1 - Behl, Marc A1 - Lendlein, Andreas T1 - Oligo(epsilon-caprolactone)-based polymer networks prepared by photocrosslinking in solution JF - Journal of applied biomaterials & functional materials N2 - Purpose: Polymer networks with adjustable properties prepared from endgroup-functionalized oligoesters by UV-crosslinking in melt have evolved into versatile multifunctional biomaterials. In addition to the molecular weight or architecture of precursors, the reaction conditions for crosslinking are pivotal for the polymer network properties. Crosslinking of precursors in solution may facilitate low-temperature processes and are compared here to networks synthesized in melt. Methods: Oligo(epsilon-caprolactone)-(z) methacrylate (oCL-(z) IEMA) precursors with a linear (z = di) or a four-armed star-shaped (z = tetra) architecture were crosslinked by radical polymerization in melt or in solution with UV irradiation. The thermal, mechanical, and swelling properties of the polymer networks obtained were characterized. Results: Crosslinking in solution resulted in materials with lower Young's moduli (E), lower maximum stress (sigma(max)), and higher elongation at break (epsilon(B)) as determined at 70 degrees C. Polymer networks from 8 kDa star-shaped precursors exhibited poor elasticity when synthesized in the melt, but can be established as stretchable materials with a semi-crystalline morphology, a high gel-content, and a high elongation at break when prepared in solution. Conclusions: The crosslinking condition of methacrylate functionalized precursors significantly affected network properties. For some types of precursors such as star-shaped telechelics, synthesis in solution provided semi-crystalline elastic materials that were not accessible from crosslinking in melt. KW - Crosslinking KW - Methacrylate KW - Multifunctional polyester networks KW - Poly(epsilon-caprolactone) KW - Polymer network properties Y1 - 2012 U6 - https://doi.org/10.5301/JABFM.2012.10372 SN - 2280-8000 VL - 10 IS - 3 SP - 273 EP - 279 PB - Wichtig CY - Milano ER -