Construction of size-controllable gold nanoparticles immobilized on polysaccharide nanotubes by in situ one-pot synthesis

A green method for in situ one-pot synthesis of size-controlled gold nanoparticles (AuNPs) was provided in this work. In our findings, a β-1,3-D-glucan, AF1, extracted from black fungus was used as a support of AuNPs. The AuNPs were dispersed in the AF1 aqueous solution without additional reducing and stabilizing or dispersing agents. The infrared spectrum (FT-IR), thermogravimetry (TG), X-ray photoelectron spectra (XPS) and atomic force microscope (AFM) results indicated that the AuNPs synthesized by AF1 were immobilized on the AF1 nanotubes with controllable shape and size of 5-45 nm. The hydroxyl groups on AF1 nanotubes not only acted as reducing agents but also were able to stabilize AuNPs by the strong interaction between the surface Au atoms of AuNPs and oxygen atoms of AF1 nanotubes. The AuNPs exhibited a good catalytic activity for the rapid reduction from 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) by excess borohydride, further confirming the dispersion of AuNPs in water.