Cellulose is the most abundant polysaccharide on Earth. It can be obtained from a vast number of sources, e.g. cell walls of wood and plants, some species of bacteria, and algae, as well as tunicates, which are the only known cellulose-containing animals. This inherent abundance naturally paves the way for discovering new applications for this versatile material. This review provides an extensive survey on cellulose and its derivatives, their structural and biochemical properties, with an overview of applications in tissue engineering, wound dressing, and drug delivery systems. Based on the available means of selecting the physical features, dimensions, and shapes, cellulose exists in the morphological forms of fiber, microfibril/nanofibril, and micro/nanocrystalline cellulose. These different cellulosic particle types arise due to the inherent diversity among the source of organic materials or due to the specific conditions of biosynthesis and processing that determine the consequent geometry and dimension of cellulosic particles. These different cellulosic particles, as building blocks, produce materials of different microstructures and properties, which are needed for numerous biomedical applications. Despite having great potential for applications in various fields, the extensive use of cellulose has been mainly limited to industrial use, with less early interest towards the biomedical field. Therefore, this review highlights recent developments in the preparation methods of cellulose and its derivatives that create novel properties benefiting appropriate biomedical applications.

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Biodegradable polyurethane (PU) elastomers with potential for biomedical and industrial applications were synthesized by the reaction of poly(ecaprolactone) (PCL) and isophorone diisocyanate (IPDI), extended with different mass ratio of chitosan and 1,4-butane diol (BDO). Their chemical structures were characterized using FTIR, 1 HNMR, and 13 CNMR, and thermal properties were determined by TGA and DMTA. Incorporation of chitosan contents into the polyurethane backbone caused improvement in thermal stability and thermal degradation rate. Optimum thermal properties and degradation profile were obtained from elastomer extended with chitosan. The crystallinity and hydrophilicity of the prepared polymers were also examined by Xray and contact angle measurements. The results showed that hydrophilicity decreased and crystallinity increased with increasing of chitosan content in polyurethane backbone.

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Polyphosphazenes form one of the most important and interesting classes of inorganic polymers having a backbone of alternating phosphorus and nitrogen atoms with phosphorus atom bearing two organic side groups. The most important feature of these polymers is the synthesis route which allows the side groups to be changed over a wide range to obtain a broad variety of products with different properties from elastomers to glasses, water soluble to hydrophobic polymers, bioinert to bioactive materials, and electrical insulators to conductors. In this paper, some novel applications of these polymers in biomedical materials and advanced devices are reviewed.