▎ 摘　　要

Highly water-soluble GO-HPEI was prepared by modifying graphene oxide (GO) with hyperbranched polyethylenimine (HPEI) containing a large number of amines to solve the problem of poor water-solubility of GO. Using GO-HPEI as reducing agent and stabilizer, Au nanoparticles (AuNPs) based colorimetric probe (GO-HPEI/AuNPs) with thermal stability up to 130 degrees C and high salt resistance was prepared in situ. The morphology and structure of GO-HPEI/AuNPs were characterized by XPS, FTIR, TEM, DLS and Zeta potential. The GO-HPEI/AuNPs can detect silver ions (Ag+) through the formation of non-aggregated and stabilized Au-Ag core-shell nanoparticles. The unusual sensing mechanism endowed this sensor with unique color variation and high selectivity. The GO-HPEI/AuNPs sensor exhibited an obvious color change from red to ochre yellow and high sensitivity (LOD=54.9 nM) with a good linear relationship in the range of 0-65.7 mu M (R-2=0.9903). Furthermore, this colorimetric sensor was successfully applied to detect Ag+ in real water samples. Therefore, the GO-HPEI/AuNPs sensor based on the formation of new nanomaterials has great potential for detecting Ag+ and analytical applications.