Modified alginates for precision drug delivery: Advances in controlled-release and targeting systems

Alginates have been modified to become a suitable platform for targeted drug release, triggering advances in targeted and controlled-release systems. Alginate chemistry and various structural modifications, including ionic crosslinking, cyclodextrin-linking, and chemical carboxyl and hydroxyl group modification, such as esterification, amidation, and sulfation, are covered in this review. These modifications are aimed at enhancing drug release mechanisms, like dissolution, diffusion, water penetration, and ion exchange-based systems. Application of modified alginates in controlled-release systems is extensive, from hydrogels, bioprinting approaches, nanofiber-based systems, in-situ gelling systems, to nanoparticle systems. Targeted drug delivery utilizes passive and active targeting strategies for numerous applications, including the treatment of cancer, inflammatory disease therapy, infectious disease, and wound healing. Emerging platforms such as hydrogels and nanoparticles provide evidence of the versatility of modified alginates. However, issues regarding scalability and biocompatibility remain as obstacles. In this review, the capabilities of alginate-based delivery systems and their role in making various release mechanisms for targeted delivery are discussed in relation to the future directions for precision medicine development.