| With the rapid development in nanotechnology,engineered metallic nanoparticles have been widely applied in the fields such as biomedicine,catalyst,and nano-enabled agriculture.In the meantime,more solid evidence have demonstrated that plants can form metallic nanoparticles in vivo,which are environmentally friendly,low-cost and bio-comparable.However,the mechanisms underlying in vivo formation of metallic nanoparticles remain largely unknown.In this study,we investigated the in vivo formation of gold nanoparticles(Au NPs)within soybean.We firstly characterized Au NPs(i.e.,particle number and size)within soybeans,which had exposed to ionic Au for 5 days,using single particle inductively coupled plasma mass spectrometry(sp ICP-MS).Then the effects of ultraviolet light exposure on the speciation and contents of free radicals in soybeans were examined using electron paramagnetic resonance spectrometer(EPR).The relationship between free radicals and Au NPs were further explored.The main results of our study are as follows:(1)Isolation method of Au NPs from plants was established.In brief,0.1 g of soybean leaves were homogenized with 8 ml citric acid buffer solution,added with 0.2 g of Macerozyme R-10,and heated in a water bath at 37 ? for 36 h.The isolated Au NPs were characterized by single particle inductively coupled plasma mass spectrometry(sp ICP-MS).(2)Effects of wavelength and exposure dose of ultraviolet light on the contents of free radicals in plants was investigated using EPR analysis.Wavelength of ultraviolet light did not have significant effects on the contents of free radicals in plants.In contrast,with increasing doses of ultraviolet radiation,free radicals in plants increased.These free radicals are mainly carbon-centered radicals.(3)No relationship was observed between changes of carbon-centered radicals contents in soybeans and gold nanoparticle numbers.Therefore,the effects of other free radicals in plants on Au NP formation remain elusive. |
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