Polyacrylonitrile‒Chitosan IPN composite scaffolds that closely mimic the human trabecular bone structure for tissue engineering

Abstract

Successful bone tissue engineering involves managing several important parameters, such as the design of intercommunicating porous structures, pore sizes, and the material and mechanical suitability of the material. In our work, we focused on the preparation of a synthetic scaffold that morphologically mimics the structure of human trabecular bone. The scaffolds were fabricated through the thermal modification (TM) of polyacrylonitrile. The scaffold strength was supported by a crosslinked chitosan supporting network. The prepared scaffold has imprinted pores of the appropriate size to facilitate the ingrowth and proliferation of human osteoblasts throughout the entire pore volume created by a primary porogen, sodium chloride. The resulting material has a dual porous morphological structure, in which adjustable larger pores support cellular ingrowth into the scaffold, whereas smaller pores, created using succinonitrile (SCN) as a secondary porogen, increase the diffusion of oxygen and nutrients to developing cells. The mechanical properties of the scaffold were promoted by the use of a secondary interpenetrating network (IPN) based on chitosan. The incorporation of secondary IPNs led to a significant improvement in the mechanical characteristics of the scaffold. Two crosslinking agents were used: the widely utilized glutaraldehyde (GA) and its green, nontoxic alternative, genipin (GEN).The current study introduces a synthetic scaffold that effectively mimics the structure of human trabecular bone, providing a conducive environment for osteoblast proliferation and ingrowth. We incorporated a dual porous morphology and a secondary IPN based on chitosan and found that the scaffold exhibited improved mechanical properties and nutrient diffusion capabilities. This research highlights the potential of these scaffolds for major advancements in bone tissue engineering, demonstrating their noncytotoxic nature and ability to support the adhesion and proliferation of the human osteosarcoma cell line SAOS-2. The described scaffold preparation technique may offer distinct advantages over current high-end methods such as 3D printing. The primary benefit lies in its very simple instrumentation, which enables the creation of a complex trabecular bone morphology with both macro- and microporosity in the bulk, which is still challenging for common 3D printers. Additionally, IPN with chitosan can be postmodified, substantially expanding the potential applications of these scaffolds.