Alginate-Based Composites in Drug Delivery

Alginate is a naturally occurring anionic polysaccharide primarily derived from brown seaweed. It has gained considerable attention as a multifunctional biomaterial for advanced drug delivery systems. Its inherent properties—such as biocompatibility, biodegradability, non-toxicity, and gentle gelation under physiological conditions—make alginate ideal for encapsulating sensitive therapeutic agents, such as proteins, peptides, and nucleic acids. The polymer’s structure, which comprises β-D-mannuronic and α-L-guluronic acid residues, allows for ionic cross-linking with divalent cations to form hydrogels that facilitate controlled and sustained drug release. This chapter examines the structural, physicochemical, and biological characteristics of alginate and its composites. To address limitations, such as poor mechanical strength and rapid dissolution, alginate is often combined with natural polymers, synthetic polymers, and inorganic nanoparticles. These hybrid systems enhance stability, bioadhesion, and stimuli-responsive release behaviour, thereby supporting a wide range of biomedical applications. Various formulation techniques, including ionotropic gelation, emulsion cross-linking, spray drying, and microfluidic encapsulation, are discussed in terms of encapsulation efficiency and release mechanisms. The chapter highlights applications across multiple delivery routes—oral, injectable, topical, pulmonary, and nasal—emphasising mucoadhesive, pH-responsive, and site-specific release profiles. Emerging strategies in cancer therapy, gene delivery, and tissue engineering demonstrate the adaptability of alginate-based systems for targeted and combination treatments. Recent advancements such as magnetic alginate ferrogels, superabsorbent alginate-silica composites, and 3D-printed alginate bioinks illustrate the ongoing evolution of this field towards precision and personalised medicine. Despite challenges related to degradation control, reproducibility, and clinical translation, alginate-based composites continue to represent a promising and sustainable platform for next-generation drug delivery technologies.