Conjugated polymers containing triphenylamine group are synthesized via Suzuki coupling polymerization. Fluorescent-conjugated polymer nanoparticles (CPN) are prepared by reprecipitation method using the newly synthesized conjugated polymer. CPN can be encapsulated with polyarginine by electrostatic interaction. The CPN modified with polyarginine exhibit excellent interaction with graphene oxide (GO) which is chemically modified with hydrophilic groups that possesses negative charge, which, in turn, induces the quenching of the fluorescence of CPN upon formation of CPN-GO nanohybrid. Upon exposure to trypsin, the quenched fluorescence is recovered by release of CPN from the nanohybrid, because trypsin cleaves the polyarginine linkage, resulting in weakening of interaction between CPN and GO. (c) 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 1898-1904