Dicyanovinyl-functionalized fluorescent hyperbranched conjugated polymer nanoparticles for sensitive naked-eye cyanide ion detection

A selective and sensitive fluorescent nanoprobe based on hyperbranched conjugated polymer nanoparticles (HBCPN-DCV) for cyanide detection was developed. HBCPN-DCV was readily prepared by Suzuki coupling polymerization in a mini-emulsion, followed by post-functionalization of numerous terminal aldehyde groups into cyanide-responsive dicyanovinyl fluorophores on the particle surface. An efficient Förster resonance energy transfer from the HBCPN core to the peripheral dicyanovinyl dyes was achieved in HBCPN-DCV. Taking advantage of the amplified energy transfer, the fluorescent turn-off cyanide detection mode of its model compound (M-DCV) could be transformed into the turn-on and ratiometric detection mode of HBCPN-DCV, with a limit of detection down to 0.2 μM. Meanwhile, clear fluorescent colour change at a cyanide concentration as low as 2 μM could be observed by the naked eye. In addition, compared to M-DCV, HBCPN-DCV exhibits higher sensitivity and wider linear region.