A Dual-Crosslinked Metallo-elastomer Platform for Architecture-Directed Vascular Remodeling

Abstract

The engineering of durable small-diameter vascular grafts remains constrained by the challenge of simultaneously achieving mechanical robustness, controlled degradation, and instructive scaffold architecture. Here, we report a programmable dual-crosslinked metallo-elastomer platform, poly(1,3-propylene itaconate-co-2,2′-bipyridine-5,5′-dicarboxylate-co-succinate-co-sebacate) (M-PBIS), that integrates dynamic metal–ligand coordination with covalent crosslinking to enable orthogonal control over network mechanics, time-dependent viscoelastic behavior, and processability. PBIS polymers were synthesized by modular step-growth polyesterification, allowing independent tuning of backbone composition, bipyridine ligand density for metal coordination, and alkene (C = C) content for covalent crosslinking. This multidimensional design space allowed systematic tuning of tensile elastic modulus (0.06–3.2 MPa), extensibility (53%–491%), toughness (66–1339 kJ m⁻³), creep resistance, and self-healing behavior, while maintaining controlled hydrolytic degradation and low physiological swelling (< 7%). Rheological analysis established a processing window supportive of conventional melt- and flow-based fabrication methods. To elucidate the role of scaffold architecture in vascular remodeling, M-PBIS was fabricated into small-diameter grafts using either poly(methyl methacrylate) (PMMA)-templated porous structures or electrowritten circumferentially-biased, helically wound fibers. In a rat carotid artery interposition model, electrowritten Zn-PBIS grafts maintained patency and dimensional stability through 21 weeks, supporting organized endothelialization, circumferential smooth muscle alignment, and structured extracellular matrix deposition. In contrast, PMMA-templated porous grafts underwent progressive dilation and structural instability during remodeling. These results demonstrate that dual-crosslinked metallo-elastomers combined with biomimetic circumferentially-biased fiber architecture enable mechanically resilient, biologically adaptive vascular grafts and establish M-PBIS as a manufacturable platform for resorbable small-diameter arterial reconstruction and other load-bearing soft-tissue applications.

Graphical abstract