Poly (vinyl alcohol) (PVA) is a hydrophilic polymer with excellent biocompatibility and has been applied in various biomedical areas due to its favorable properties. PVA-based hydrogels have been recognized as promising biomaterials and suitable candidates for tissue engineering applications and can be manipulated to act various critical roles. However, due to some disadvantages (i.e., lack of cell-adhesive property), they needs further modification for desired and targeted applications. This review highlights recent progress in the design and fabrication of PVA-based hydrogels, including crosslinking and processing techniques. Finally, major challenges and future perspectives in tissue engineering are briefly discussed. GRAPHICAL ABSTRACT

The sharp increase in the use of cellulose seems to be in increasing demand in wood; much more research related to sustainable or alternative materials is necessary as a lot of the arable land and natural resources use is unsustainable. In accordance, attention has focused on bacterial cellulose as a new functional material. It possesses a three-dimensional, gelatinous structure consisting of cellulose with mechanical and thermal properties. Moreover, while a plant-originated cellulose is composed of cellulose, hemi-cellulose, and lignin, bacterial cellulose attributable to the composition of a pure cellulose nanofiber mesh spun is not necessary in the elimination of other components. Moreover, due to its hydrophilic nature caused by binding water, consequently being a hydrogel as well as biocompatibility, it has only not only used in medical fields including artificial skin, cartilage, vessel, and wound dressing, but also in delivery; some products have even been commercialized. In addition, it is widely used in various technologies including food, paper, textile, electronic and electrical applications, and is being considered as a highly versatile green material with tremendous potential. However, many efforts have been conducted for the evolution of novel and sophisticated materials with environmental affinity, which accompany the empowerment and enhancement of specific properties. In this review article, we summarized only industry and research status regarding BC and contemplated its potential in the use of BC.

The engineering of tissues under a three-dimensional (3D) microenvironment is a great challenge and needs a suitable supporting biomaterial-based scaffold that may facilitate cell attachment, spreading, proliferation, migration, and differentiation for proper tissue regeneration or organ reconstruction. Polysaccharides as natural polymers promise great potential in the preparation of a three-dimensional artificial extracellular matrix (ECM) (i.e., hydrogel) via various processing methods and conditions. Natural polymers, especially gums, based upon hydrogel systems, provide similarities largely with the native ECM and excellent biological response. Here, we review the origin and physico-chemical characteristics of potentially used natural gums. In addition, various forms of scaffolds (e.g., nanofibrous, 3D printed-constructs) based on gums and their efficacy in 3D cell culture and various tissue regenerations such as bone, osteoarthritis and cartilage, skin/wound, retinal, neural, and other tissues are discussed. Finally, the advantages and limitations of natural gums are precisely described for future perspectives in tissue engineering and regenerative medicine in the concluding remarks.

Hydroxyapatite (HAp) has been considered for decades an ideal biomaterial for bone repair due to its compositional and crystallographic similarity to bioapatites in hard tissues. However, fabrication of porous HAp acting as a template (scaffold) for supporting bone regeneration and growth has been a challenge to biomaterials scientists. The introduction of additive manufacturing technologies, which provide the advantages of a relatively fast, precise, controllable, and potentially scalable fabrication process, has opened new horizons in the field of bioceramic scaffolds. This review focuses on three-dimensional-printed HAp scaffolds and related composite systems, where the calcium phosphate phase is combined with other ceramics or polymers improving the mechanical properties and/or imparting special extra-functionalities. The main applications of three-dimensional-printed HAp scaffolds in bone tissue engineering are presented and discussed; furthermore, this review also emphasizes the most recent achievements toward the development and testing of multifunctional HAp-based systems combining multiple properties for advanced therapy (e.g., bone regeneration, antibacterial effect, angiogenesis, and cancer treatment).