Cellulose and its derivatives: understanding physicochemical properties and their applications in pharmaceutical formulations

Cellulose, the most naturally abundant biopolymer, continues to attract considerable scientific and industrial interest due to its renewability, biodegradability, and diverse physicochemical properties. As a structural polysaccharide found across a range of botanical and microbial sources, cellulose holds significant potential for pharmaceutical applications, particularly as an excipient, carrier, and functional biomaterial. This review provides a comprehensive and structured examination of cellulose and its derivatives, beginning with their origins, chemical structure, and hierarchical organisation, and extending to the physicochemical properties that underpin their functionality in pharmaceutical formulation science. Particular emphasis is given on extraction techniques, chemical, enzymatic and mechanical, with a critical evaluation of the experimental variables that influence yield and purity. The review also addresses strategies for cellulose dissolution, focusing on both derivatising and non-derivatising solvent systems, and highlighting the emergence of ionic liquids and molten salts as environmentally sustainable alternatives. To broaden the utility of cellulose and its derivatives in advanced drug delivery systems, various chemical modification routes, such as etherification, esterification, and crosslinking, are explored for their roles in improving solubility, mechanical strength, thermal stability, and bioavailability. In addition, the review discusses the unique properties of bacterial cellulose and nanocellulose, including high surface area, exceptional mechanical integrity, and excellent biocompatibility, which make them attractive candidates for wound care, tissue engineering, and targeted delivery systems. Overall, this review underscores the transformative role of cellulose and its derivatives in the advancement of sustainable pharmaceutical technologies. Further research into green processing methods, surface functionalisation, and in vivo performance characterisation is essential to realise the full potential of cellulose-based drug delivery platforms and medical devices.