Retracted: A Photoclick Thiol‐Ene Collagen‐Based Hydrogel Platform for Skeletal Muscle Tissue Engineering

Abstract

UV‐cured collagen‐based hydrogels hold promise in skeletal muscle regeneration due to their soft elastic properties and porous architecture. However, the complex triple helix conformation of collagen and environmental conditions, i.e., molecular oxygen, pose risks to reaction controllability, wet‐state integrity, and reproducibility. To address this challenge, a photoclick hydrogel platform is presented through an oxygen‐insensitive thiol‐ene reaction between 2‐iminothiolane (2IT)‐functionalized type I collagen and multiarm, nonhomopolymerizable norbornene‐terminated polyethylene glycol (PEG). UV‐induced network formation is demonstrated by oscillatory time sweeps on the reacting thiol‐ene mixture, so that significantly increased storage moduli are measured and adjusted depending on the photoinitiator concentration. Variations in PEG functionality (4‐arm and 8‐arm) and PEG content generate hydrogels with skeletal muscle native stiffness (Ec = 1.3 ± 0.2‒11.5 ± 0.9 kPa), diffusion‐controlled swelling behavior and erosion‐driven degradability. In vitro, no cytotoxic effect is detected on C2C12 murine myoblasts, while myogenic differentiation is successfully accomplished on hydrogel‐seeded cells in then low serum culture medium. In vivo, 7 d subcutaneous implantation of selected thiol‐ene hydrogel in rats reveal higher cell infiltration, blood vessel formation, and denser tissue interface compared to a clinical gold standard collagen matrix (Mucograft, a trademark of Geistlich Biomaterials). These results, therefore, support the applicability and further development of this hydrogel platform for skeletal muscle regeneration.

γ-Functional Iminiumthiolactones for the Single and Double Modification of Peptides

“… With this small alteration comes a large increase in water solubility and reactivity toward primary amines at a physiologically compatible pH range of pH = 7–9 . Since its invention in 1973, the Traut’s reagent has been continuously used to modify biological molecules (e.g., proteins, enzymes, ribosomes) and anchor them to surfaces, , tags, , or other (bio)­macromolecules. , Despite its popularity, Traut’s reagent can only be purchased as an unsubstituted five-membered heterocycle. ITL derivatives with substitutions on the heterocycle have only been reported twice by Carroll and co-workers. , In the respective publications, the authors investigated the impact of various alkyl and phenyl substitutions on the reactivity and stability of the ITL derivatives.…”