▎ 摘　　要

Poly(4-vinylpyridine) (P4VP), a pH-sensitive polymer, was employed to non-covalently functionalize graphene oxides (GOs) through pi-pi stacking interactions. Citrate-capped Au nanoparticles (Au NPs) were then immobilized onto the P4VP-grafted GO, yielding pH-responsive Au NPs-GO nanocomposites. Such Au NPs-GO nanocomposites displayed pH-responsive localized surface plasmon resonance (LSPR) changes and assembly behavior due to protonation and deprotonation of the pyridine units of P4VP molecules. The catalytic activity of the Au NPs-GO nanocomposites was evaluated using the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) as a model reaction, and demonstrated significantly high catalytic activity and stability at low pH (2.0), which was 4-fold higher than that at high pH (5.0). Furthermore, our results indicated that the Au NPs-GO nanocomposites induced active adsorption and selective SERS detection of negatively charged analytes under low pH conditions, and are therefore highly attractive for real-world chemical detection.