Collagen-Based Micro/Nano Fibrous Constructs: Step-By-Step Reverse Biomimetics of Structure and Mechanical Function

Abstract

Multiscale micro−nano fibrous structures are a cutting-edge research area in material science and have drawn the attention of scientists in recent years. These structures are widely distributed in nature's materials and hold fascinating and unique properties, such as mechanical behaviors, high surface area to volume ratio, and special multiscale biological functionalities. Herein, we demonstrate step-by-step biomimetics of a multiscale composite material system and the influence of the different structural mechanisms on mechanical behavior. This is done using systematic biomimetics and investigation of the mechanical effect of every constituent. We have fabricated and characterized mechanically and structurally different material systems to get a comprehensive understanding of the structure−function relationship in multiscale biomimetic constructs (MSBCs) and examine the influence of the material selection and structure. We first characterized the electrospun nanofibers made of polyamide 6 (PA6) and gelatin-polyamide 6 (GPA6) and then constructed and characterized the combined constructs. Our micro−nano fibrous structures were constructed from combined unique coral collagen microfibers and PA6 and GPA6 nanofibers. These hierarchical structures demonstrated an entangled network of nanobridges among the micro collagen fibers. However, the GPA6-collagen structures showed better connectivity with the microfibers and were significantly stiffer and stronger than the PA6-collagen structures due to the material compatibility. Furthermore, our structures demonstrated a considerable resemblance with soft tissue structures. We embedded the MSBC in alginate hydrogel to form biocomposites that displayed a hyperelastic nonlinear behavior with significantly improved toughness and a remarkable similarity to the mechanical behavior of native soft tissues. Our results present great potential to be further developed as tailor-designed multiscale next-generation specialized structures for soft tissue repair and replacement.