Biological Effects Of Three Kinds Of Gold Nanoparticles On Two Economic Crops

Sub-nanometre sized noble metal nanoclusters (NCs), with dimensions between metal atoms and nanoparticles, have not yet understanding on their potential health impacts for exposed organisms. In this study, we used citrate coated～13nm gold nanoparticles (AuNPs), histidine (His) and BSA coated≤2nm gold nanoclusters (AuNCs) to investigate effects of particle size and coating on biological responses for Au in three model organisms, Capsicum annuum L. var. grossum (Willd.) Sendtn (capsicum annuum) and Zea mays L. sinensis Kulesh (waxy corn). The Au uptake, growth performance, stress levels, membrane damage, and antioxidant responses in seedlings were analyzed. Growth inhibition of a seedling exposed to different concentrations (0,1,10,20,40mg/L or0,1,5,10,20mg/L) of AuNC/NPs was examined. Only AuNCs were toxic to plants, especially stable AuNCs@His.Under the same concentration (20mg/L), Au was detected in capsicum annuum shoot limited to two AuNCs (<2nm) exposure only, imply that AuNCs upward transport from root. Au content is detected in every exposure to wheat shoots and only show significantly at40mg/L AuNCs@His, whereas no bioaccumulation of Au was detected for any treatment in waxy corn shoot except20and40mg/L AuNCs@His. What’s more, Au content in waxy corn shoots has increased dramatically along with the raise time extension at the low concentration(1mg/L) AuNCs@His. CAT activity varied complicatedly in the waxy corn body, POD activity and MDA content in each treatment (except had no change in AuNCs@His) were lower than the control to a certain degree in roots. With the increasing of AuNCs@His concentration, CAT, POD and SOD activity and MDA content in the capsicum annuum rised, and reached maximum at l0mg/L. Comparison of the fluorescence spectra and UV absorption spectrum of three gold nanoparticles was added into the culture solution before/after (7days). It is found that only the fluorescence intensity of AuNCs@His did not change while the other two changes have occurred, indicating the nature of the two materials changed.These results suggested that that the stable nano-material with the smaller size will be considerably more persistently damaging to the environment.