To explore this hypothesis, and to confirm the availability of the DNA sequence for polymerase processing, a GFP expression cassette (1.3 kb) was cloned into two plasmids with different sizes (3.2 kb and 12 kb, Fig. ). A short 1.3 kb ORF gene sequence is more likely to be present fully in the uncondensed parts of the DNA of a 12 kb plasmid and thus available to the cellular transcription machinery for expression. In contrast, the same short OFR on a 3.2kb plasmid is more likely to strongly condense on the PEI 30 -SWCNT +61mV , and therefore we hypothesize that the ORF sequence is relatively less available to the transcription machinery. The constructed plasmid DNAs were conjugated at a 1:3 ratio with the PEI 30 -SWCNTs and were subjected to a cell-free protein expression system. A low GFP expression signal was detected from GFP cassettes cloned onto the 12 kb plasmid under UV light, but only a minimal GFP signal was observed from the GFP cassette cloned onto the small plasmid (Fig. ). The in vitro transcription results suggest the availability of the GFP cassette when cloned into the 12 kb plasmid and conjugated onto PEI 30 -SWCNT +61mV but poor or no availability for expression from the small (3.2 kb) plasmid harboring the GFP cassette conjugated to PEI 30 -SWCNT +61mV . The unbound plasmid DNA was used as a positive expression control. This data demonstrated that the relative size of the gene with respect to the plasmid size determines the expression efficiency in vitro in the plasmid DNA bound to PEI 30 -SWCNT +61mV composites and its putative accessibility once inside the plant cell.