Bio-inspired metamaterial structured small-diameter vascular grafts for emulation of native arterial mechanics

To address the issue that the mechanical strength and compliance of traditional small-diameter artificial blood vessels are difficult to balance, leading to easy thrombosis and subsequent failure after transplantation, this study, inspired by the corrugated structure of collagen fibers, designs and fabricates a metamaterial composite tubular small-diameter artificial blood vessel. This design employs a gelatin-based hydrogel as the matrix phase to simulate the extracellular matrix of natural arteries, leveraging its high biocompatibility. The reinforcement phase is an ultra-fine fiber network with a metamaterial structure manufactured by high-precision 3D printing; this network mimics the curled morphology of collagen fibers and endows the composite tubular scaffold with the ability to reproduce the J-shaped stress-strain characteristics of natural arteries. Meanwhile, by adjusting the parameters of the metamaterial structural units, the axial modulus and burst resistance strength of the composite tubular scaffold can be regulated within the ranges of 0.091-0.55 MPa and 820-3250 mmHg, respectively, thereby matching the mechanical strength of natural arteries in various parts of the human body. On the basis of meeting high mechanical strength requirements, the design of the metamaterial structure enables the compliance of the composite tubular scaffold to be adjusted within the range of 6.25-13.28%, achieving compliance matching with natural arteries. This research provides an idea for the design and fabrication of artificial blood vessels.