Current approaches in developing porous 3D scaffolds face various challenges, such as failure of mimicking extracellular matrix (ECM) native building blocks, non-sustainable scaffold fabrication techniques, and lack of functionality. Polysaccharides and proteins are sustainable, inexpensive, biodegradable, and biocompatible, with structural similarities to the ECM. As a result, 3D-structured cellulose (e.g., cellulose nanofibrils, nanocrystals and bacterial nanocellulose)-based aerogels with high porosity and interconnected pores are ideal materials for biomedical applications. Such 3D scaffolds can be prepared using a green, scalable, and cost-effective freeze-drying technique. The physicochemical, mechanical, and biological characteristics of the cellulose can be improved by incorporation of proteins and other polysaccharides. This review will focus on recent developments related to the cellulose-based 3D aerogels prepared by sustainable freeze-drying methods for tissue engineering applications. We will also provide an overview of the scaffold development criteria; parameters that influenced the aerogel production by freeze-drying; and in vitro and in vivo studies of the cellulose-based porous 3D aerogel scaffolds. These efforts could potentially help to expand the role of cellulose-based 3D scaffolds as next-generation biomaterials.

Keratin was extracted from chicken feather to produce scaffolds with poly(3-hydroxybutyrate) (P(3HB)) for tissue engineering applications. The scaffolds with different concentrations (10%, 20%, and 30%) of keratin were produced by electrospinning. The keratin presence in the produced scaffold was confirmed by FTIR analysis. The surface wettability of the P(3HB)/keratin scaffold was much higher compared to neat P(3HB) scaffold because of hydrophilic nature of the keratin. All the scaffolds showed over 80% porosity with an average fiber diameter of less than 750 nm. Mechanical properties of the P(3HB) scaffolds with up to 20% keratin were superior compared to neat P(3HB) scaffold. However, the mechanical properties of the P(3HB)/keratin scaffolds were deteriorated when the keratin concentration was 30% in the scaffold. The observed mechanical properties reduction was mainly attributed to the poor interaction between the keratin and P(3HB) matrix. Due to better biocompatibility of keratin, cell culture studies suggested that the P(3HB)/keratin scaffolds can have better cell attachment and proliferation compared to the neat P(3HB) scaffold. Owing to good biological response and mechanical properties, the P(3HB)/keratin scaffolds with an optimal concentration of keratin (20%) could be used as potential material for tissue engineering application.