Fig. 6. Chloroplast specific subcellular tuning of oxidative status by targeted delivery of nanoparticles with biochemical cargoes.

a Confocal microscopy images of Arabidopsis leaf mesophyll cells illustrating the targeted generation and scavenging of superoxide anion (detected by DHE fluorescent dye) in chloroplasts by MV-Chl-QD and Asc-Chl-QD guided by peptide recognition motifs, respectively. Scale bar, 40 µm. b Comparison between chemical and nanotechnology-based approaches for specifically increasing superoxide in chloroplasts. DHE was used as an indicator for superoxide ROS levels after 6 h. Chemicals and nanomaterials were treated at the time points specified in the legend. Box plot error bars represent standard deviation, boxes are the interquartile range from the first to the third quartile with squares as the medians, and horizontal line represents the mean. c Temporal patterns of DHE fluorescence signal intensity inside chloroplasts in leaf mesophyll cells showing the specific increase and subsequent decrease of chloroplast superoxide anion levels in plants infiltrated with MV-Chl-QD (n = 4) at time 0 h and subsequently perfused with Asc-Chl-QD at time 3 h (purple line). A steady increase in DHE intensity was observed in leaves treated with MV-Chl-QD at time 0 h and 3 h (n = 5) (cyan line). Leaves infiltrated with MV-Chl-QD (n = 4) at time 0 h only (orange line) showed an increase in DHE signal that plateaus. Controls were performed for leaves infiltrated only with buffer (n = 5) (dark gray line). Values are means and ± indicates standard deviation. Statistical comparisons were performed by one-way ANOVA based on Duncan’s multiple range test (two tailed). Lower case letters represent significance at P < 0.05. NS denotes not significant.