LAUSR

Abstract The development of novel imaging agents for fluorescence detection of latent fingerprint is still important for criminal investigation and identity recognition. Herein, we reported a simple and robust method to prepare multi-color conjugated polymer micelles for visualization of fingerprints. A conjugated polyelectrolyte, poly[(9,9-bis(3′-((N,N-dimethyl)-N-ethylammonium)-propyl)-2,7-fluorene)-alt-2,7-(9,9-dioctylfluorene)] (PFN), was dissolved in water forming polymer micelles with blue emission. Green and red emissions were facilely achieved by incorporating small organic fluorophores including coumarin 6 (C6) and Nile red (NR) into the PFN micelles, respectively. These micelles exhibited bright fluorescence both in solution and solid film, where significant aggregation-caused quenching was avoided and fluorescence resonance energy transfer from PFN to C6 or NR was enhanced. Through a simple solution method, these polymer micelles proved their high affinity towards the fingerprint ridges. Accordingly, fluorescent fingerprint images with high-resolution were obtained, which were less interfered by fluorescence background from substrate and overlap between adjacent fingerprints.