Silver (Ag) plays an important role in a wide range of fields,including catalysis [1–3], photonics [4] and biomedicine (e.g. diag-nosis or imaging [5], antimicrobial agent [6–9] and cancer therapy[10]). Ag nanoparticles have recently gained much attention dueto large surface-to-volume ratio, optical properties by plasmonresonance [11] and convenient surface bioconjugation [12]. Agnanocatalysts are particularly useful in both ethylene and methanoloxidation [1,2] as well as reduction of nitric oxides (NOx) oraromatic nitro compounds [3,13–15]. For example, catalytic hydro-genation of 4-nitrophenol is a simple, efficient and environmentallyfriendly process to produce 4-aminophenol [13–16], a useful phar-maceutical intermediate for the production of several analgesic andantipyretic drugs such as paracetamol, acetanilide and phenacetin[17]. In addition, Ag has been used as an antimicrobial agent for cen-turies, mainly rising from the adsorption and penetration into thecell wall, thus disturbing cellular respiration and damaging phos-phorus or sulfur-containing compounds such as DNA and proteins[7–9]. Ag nanoparticles have been reported to be suitable materi-als for the antibacterial application mainly due to low Ag amountneeded, low toxicity to human cells, and large surface area forimproved interaction with bacterial cells