Formation of Polydopamine Nanofibers with the Aid of Folic Acid

Abstract Polydopamine (PDA) generated by the oxidative self‐polymerization of dopamine shows great potential for surface modification. Observed PDA nanostructures are nanoparticles and thin films. The formation mechanism of PDA is still unclear; thus, the manipulation of PDA nanostructures is a big challenge. In this study, we first demonstrated that folic acid shows a dramatic effect on the PDA nanostructure: New aggregated nanostructures of PDA, nanobelts and nanofibers, were generated in a dopamine/folic acid system. We hypothesized that folic acid may be involved in the stacking of protomolecules of PDA by π–π interactions and hydrogen bonding. Herein we describe the first experimental strategy to manipulate the aggregation of PDA by using small molecules. This study not only provides a new method for generating PDA nanofibers, which are proposed bioorganic electronic materials, but also a possible way to understand the formation mechanism of PDA and its analogues in nature, melanins.