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In engineering application,attachment of two(or more)dissimilar materials with very different mechanical properties is always a fundamental challenge.An abrupt transition between materials would lead to high level of stress concentration at their interface and such a stress concentration will always lead to material failures at levels of mechanical loads that are too small to cause failure in either material.An effective biologic solution to such problem may exist in some extreme "bi-material interfaces" in nature The tendon-to-bone attachment connects two highly ordered hierarchical tissues with two distinct structures and compositions.Youngs modulus of tendon is less than 0.4 GPa in the direction of muscle force and 20 GPa for bone.It is facing three challenges from high level of stress concentration,overuse injuries and a big range of motion.To meet such biological function the tendon-to-bone attachment of must achieve superior mechanical properties,such as high strength,toughness and a long fatigue lifetime.From the clinical research,surgical repair of tendon-to bone attachment at the rotator cuff is therefore prone to re-injury,with failure rates up to 94%for rotator cuff reattachment.Depending on this,the special structure may play a key role in improving its physical mechanical properties.The tendon-to-bone attachment has been categorized into four zones: tendon(contains well-aligned collagen fibers),fibrocartilage,mineralized fibrocartilage(is demarcated by the "tidemark")and bone.The change in tissue composition and structure is continuous thus forms a "functionally graded".This feature is necessary to minimize stress concentrations and aid in the efficient transfer mechanical loads across an interface with a nearly two order of magnitude stiffness mismatch and with a large difference in material organization of load between tendon and bone.Recent researches indicate that the proportion of collagen-mineral and the compliance of collagen fiber at the micro scale are dominant factors in determining the tensile mechanical property of whole tendon-to-bone attachment.Increasing mineral content of the collagen fibers in the tendon-to-bone attachment causes a stiffening of themselves.When connectivity of mineral exists from one end of the fiber to the other,force transferred through this mineral becomes significant relative to that transferred through the collagen,and so the modulus of the fiber increases overall.Mechanically,the fiber orientation distribution is another dominant factor determining the stiffness of the tendon-to-bone attachment and the fiber alignment decreases across the tendon-to-bone insertion,reducing tissue stiffness precipitously.In this paper,we imitated the construction of the tendon-to-bone attachment and constructed a biomimetic functionally gradient materials through the multi-materials 3D printing technology.This new strategy may shed some light on joining dissimilar materials with very different mechanical properties.