Chemistry of Polydopamine - Scope, Variation, and Limitation

Polydopamine (PDA) is a polymer easily obtained by oxidation of dopamine. It is composed of indole and dopamine units in various oxidation states and to a lesser extent of pyrroles. It adheres to all type of surfaces even under water due to its abundant catechol moieties assisted by amino groups. This property together with a widespread reactivity to nucleophiles and electrophiles allowing linkage of a variety of entities renders PDA extremely interesting for various applications in biology, biomedicine, membranes, catalysis, materials and water purification. The field of PDA is violently developing. The present review gives an overview about the chemistry and properties of PDA and its analogues with the focus on recent publications. Their widespread applications are occasionally touched. Analogues are obtained by two strategies: post-modification of PDA and oxidative polymerization of dopamine analogues. Scope and limitations of these strategies are worked out giving impulses for future research in the field.