Infiltration of the TRBO-BFP (11.3-kb Agrobacterium system) plasmid via PEI 30 -SWCNT also resulted in low expression in the cells with 0.05±0.06% efficiency of the BFP relative to the Agrobacterium system as measured by confocal microscopy (Fig. ; panels 3,4). As a control, no GFP or BFP signal was detected in the leaves infiltrated with plasmid pK2GW7 (without the fluorescent protein gene) conjugated with PEI 30 -SWCNT (Fig. ; panel 5). Based on the above assays, our results suggest a very low expression of large functional DNA cassettes (10.6 and 11.3kb plasmids) when delivered with the PEI-SWCNT system. Taken together, the expression of reporter genes from plasmids (both 4.2 kb and 12 kb) complexed to PEI 30 -SWCNT is weak when compared with Agrobacterium.