Replication of polypyrrole with photonic structures from butterfly wings as biosensor

► Polypyrrole (PPy) with photonic structures from butterfly wings was synthesized based on a two-step templating and in situ polymerization process. ► The hierarchical structures down to nanometer level were kept in the resultant PPy replicas. ► The PPy replicas exhibit brilliant color due to Bragg diffraction through its ordered periodic structures. ► The PPy replicas showed a much higher biological activity compared with common PPy powders as a biosensor.