Aerogel-Based Materials in Bone and Cartilage Tissue Engineering—A Review with Future Implications

Abstract

Aerogels are fascinating solid materials known for their highly porous nanostructure and exceptional physical, chemical, and mechanical properties. They show great promise in various technological and biomedical applications, including tissue engineering, and bone and cartilage substitution. To evaluate the bioactivity of bone substitutes, researchers typically conduct in vitro tests using simulated body fluids and specific cell lines, while in vivo testing involves the study of materials in different animal species. In this context, our primary focus is to investigate the applications of different types of aerogels, considering their specific materials, microstructure, and porosity in the field of bone and cartilage tissue engineering. From clinically approved materials to experimental aerogels, we present a comprehensive list and summary of various aerogel building blocks and their biological activities. Additionally, we explore how the complexity of aerogel scaffolds influences their in vivo performance, ranging from simple single-component or hybrid aerogels to more intricate and organized structures. We also discuss commonly used formulation and drying methods in aerogel chemistry, including molding, freeze casting, supercritical foaming, freeze drying, subcritical, and supercritical drying techniques. These techniques play a crucial role in shaping aerogels for specific applications. Alongside the progress made, we acknowledge the challenges ahead and assess the near and far future of aerogel-based hard tissue engineering materials, as well as their potential connection with emerging healing techniques.

Hybrid and Single-Component Flexible Aerogels for Biomedical Applications: A Review

“…The most widely used natural polymers in the field of biomedical applications are bacterial polyesters [81,82] (e.g., bacterial cellulose [83,84]), proteins (e.g., collagen, silk [83,85], gelatin [84], and fibrin), and polysaccharides (e.g., alginate [80], hyaluronic acid [81], and chitosan [82]), which stand out as extensively employed natural polymers in the realm of biomedical applications [86]. These polymers find utility in diverse formats, such as 3D porous scaffolds, hydrogels, nanoparticles, composites, and absorbent sponges [87]. Researchers have delved into modifying existing natural biopolymers and synthesising novel ones to enhance characteristics like solubility, degradation rate, toxicity, immunogenicity, and stability.…”

Compendium of Safety Regulatory for Safe Applications of Aerogels

“…Concerning aerogels in textiles, they received attention in this century for producing protective clothing for space exploration, as the first application, and successively for thermal insulation textiles [22]. Recently, the new emerging applications include aerogels as textiles for wound care medical applications [23,24], face masks [25] and tissue engineering applications [26,27], thermal insulating [28], smart clothes, prevention of electromagnetic radiation, protection against chemicals, flame retardancy and treatment of textile process wastes [29,30]. Regarding the environmental applications, aerogels are ideal materials for thermal insulations which can save energy and help to reduce carbon emissions due to their low thermal conductivity.…”