The last few decades have witnessed a significant push to replace synthetic polymers for biodegradable natural polymers. Natural polymers composed of polysaccharides (cellulose, chitosan, alginate, etc.) or proteins (silk, fibroin, gelation) offer not only low-cost, wide availability, biocompatibility, and biodegradability but also a rich chemical functionality towards custom modifications and new applications. Among those, and although cellulose and chitosan are probably the most used biopolymers towards the development of analytical applications, sodium alginate (ALG) offers a number of competitive advantages. ALG is a linear anionic biopolymer extracted from brown algae, composed by β-D-mannuronate (M) and α-L-guluronate (G) units linked by β-1,4 and α-1,4 glycosidic bonds.