To confirm the delivery and expression of this larger 11. Nevertheless, infiltration of the same 11.3-kb plasmid via PEI 30 -SWCNT resulted in minimal, localized GFP signal around the infiltration site under UV light (Fig. ). Similarly, in confocal imaging, GFP expression was detected in almost all the cells when the construct was translocated via Agrobacterium. In contrast, in DNA-PEI 30 -SWCNT infiltrated leaves, GFP expression was observed only in few cells, with 0.09±0.02% (mean ± SD) efficiency (relative to Agrobacteriuminfiltrated leaves, N = 3 and 12 for Agrobacterium and SWCNT-treated leaves, respectively) (Fig. ; panels 1,2). The efficiency was calculated based on the integrated fluorescence intensity collected from GFP-expressing cells in 10 imaging fields in PEI-SWCNT-and Agrobacteriuminfiltrated leaves measured 5 days post-infiltration. By increasing the gain parameter in the microscope software, the barely detected fluorescence became evident in the PEI 30 -SWCNT infiltrated cells (Inset in Fig. ). Agrobacterium control showed homogeneous GFP fluorescence across the infiltrated leaves because Agrobacterium can move in the leaf tissue and can spread the TRBO-G. On the other hand, the PEI-SWCNT systems resulted in an inhomogeneous distribution of the GFP fluorescence because SWCNTs bound DNA cassette is localized to the cells in contact, and therefore, the expression of GFP is limited to these cells.