1. Introduction. With the intriguing physicochemical, nontoxic, biological and catalytic properties and the ease of functionalization, gold nanoparticles have attracted a lot of interest and have many potential applications, e.g. catalysis (Ansar et al., 2017, Haruta et al., 1989), medical diagnosis (Huang et al., 2007), biomedical imaging (Chen et al., 2013, …