Solution-dispersible hyperbranched conjugated polymer nanoparticles (FT-HBCPNs) consist of an intrinsic crosslinked rigid skeleton structure of both 9,9-dihexyl-fluorene and triphenylamine repeating units, and are synthesized via the miniemulsion Suzuki polymerization, and FT-HBCPNs for highly selective and sensitive Fe3+ fluorescent detection and their application in logic gate at molecular level are successfully developed. FT-HBCPNs with an average particle size of 10.6 nm can disperse in common organic solvents. FT-HBCPNs show high selectivity and sensitivity for Fe3+ over other commonly co-existent metal ions in THF solution with a detection limit of 3.65 x 10(-8) mol L-1. Furthermore, homogeneous transparent thin films of FT-HBCPNs developed by a simple spin-coating method can be reversibly quenched by Fe3+ with a detection limit of 3.09 x 10(-7) mol L-1. Using Fe3+ and EDTA as chemical inputs and the fluorescence intensity signal as outputs, FT-HBCPNs films can be utilized as a logic gate at molecular level. (C) 2016 Wiley Periodicals, Inc.