Coordination-driven assembly of alginate networks: From egg-box structures to bioactive delivery applications

Alginate is a biodegradable and renewable natural polysaccharide that has been extensively investigated for the design of macromolecular delivery systems. This review presents an overview of alginate-based microparticles regarding the relationship between molecular structure, gelation behavior, and functional performance. The impacts of main structural parameters (mannuronic to guluronic acid (M/G) ratio, molecular weight, and block distribution) are discussed comprehensively. Particular attention is given to Ca2+-mediated ionic gelation, including egg-box junction zone formation and the development of three dimensional hydrogel networks. Different production strategies such as external and internal gelation, emulsification, and microfluidic approaches are evaluated in terms of their impact on particle morphology and network homogeneity. In addition, the effects of formulation and process parameters on encapsulation efficiency, mechanical stability, and mass transfer behavior are analyzed. Furthermore, release mechanisms are discussed in relation to network structure and polymer-solute interactions. The environmental significance of alginate-based systems is also emphasized as sustainable alternatives to synthetic polymeric carriers.