Sodium polyaspartate
Sodium polyaspartate is a sodium salt of polyaspartic acid. It is biodegradable condensation polymer based on the amino acid aspartic acid. Polymerization. The polymerization reaction is an example of a step-growth polymerization to a polyamide. In one procedure, aspartic acid polymerizes at 180 °C concomitant with dehydration and the formation of a poly(succinimide). The resulting polymer reacts with aqueous sodium hydroxide, which hydrolyzes one of the two amide bonds of the succinimide ring to form a sodium carboxylate. The remaining amide bond is thus the linkage between successive aspartate residues. Each aspartate residue is identified as  α or β according to which carbonyl of it is part of the polymer chain. The α form has one carbon in the backbone in addition to the carbonyl itself (and a two-carbon sidechain) whereas the β form has two carbons in the backbone in addition to the carbonyl itself (and a one-carbon sidechain). This reaction gives a sodium poly(aspartate) composed of approximately 30% α-linkages and 70% β-linkages. Potential applications. As it can be synthesized in an environmentally friendly way and is biodegradable, polyaspartate is a potential green alternative to several materials such as sodium polyacrylate  used in disposable diapers and agriculture. In addition and due to its water-solubility and ability to chelate metal ions, polyaspartate is a promising biodegradable anti-scaling agent and a corrosion inhibitor. Sodium polyaspartate also has a variety of biomedical applications. Its high affinity with calcium has been exploited for targeting various forms of drug-containing carriers to the bone.  The main component of bone is hydroxyapatite (ca. 70%) (mineralized calcium phosphate). Apart from bone targeting, this polymer has been modified for other potential biomedical applications such as drug delivery, surface coating, DNA delivery, mucoadhesion, and beyond. Sodium polyaspartate Sodium