MOLECULAR TRANSPORT IN PLANT CELLS USING HiPCO® SINGLE WALLED CARBON NANOTUBES
Transportation of molecules into plant cells is more challenging compared to animal cells. Their extra cell wall acts as a barrier in addition to the cell membrane. The cell wall’s complex structure has limited the use of DNA for promising genetic engineering application in plant cells . Current delivery methods suffer from host-range limitations, low transformation efficiencies, tissue damage or unavoidable DNA integration into the host genome  .
Single-Walled Carbon Nanotubes (SWCNTs) have the unique ability to easily penetrate cell membranes to deliver biomolecules into living cells with low cytotoxicity. SWCNT-mediated delivery is attractive due to its simple, highly efficient, cost-effective, non-destructive, fast, species-independent and scalable properties .
By grafting DNA on SWCNT scaffolds, Markita P. Landry and his group in the USA have developed HiPCO® SWCNTs-based plant transformation. The method promises high- efficiency and species-independent delivery of plasmid DNA into plant cells. Due to the high aspect ratio, the HiPCO® SWCNT improved efficiency by 85% aiding an increased conjugation of DNA on SWCNTs . HiPCO® SWCNTs having a diameter smaller than the pore size of the plant cell wall (below ~20nm), provide a solution to traversing DNA into the intact cell wall for high-throughput molecular transport .
HiPCO® SWCNT is used as a template for conjugating different molecules like SWCNT/fluorescein isothiocyanate (FITC act as fluorescein tag) and SWCNT/DNA. The SWCNT carriers have compatibility for different molecules. The FITC molecule was used to verify the cell-penetration ability of SWCNT. SWCNT/FITC and SWCNT/DNA conjugates showcase the material’s ability to carry various molecules through the cell wall and cell membrane. SWCNT serves both physical adsorptions of FITC due to its hydrophobicity and bonding of DNA on functionalized CNT helping in the delivery of different cargoes into different plant cell organelles 
For species-independent transportation, HiPCO® SWCNT nano-carriers have strong native Near-infrared (NIR) fluorescence behavior, useful for tracking cargo–nanoparticle complexes in plant cells without damaging tissues, avoiding an additional fluorescent tag.
Connor Sweeney found that Chitosan-wrapped HiPCO® SWCNTs (CS–HiPCO® SWCNTs) offer high surface charge reactivity and high selectivity of DNA transfer into the cell wall of matured plants. Chitosan-based positively charged SWCNT carriers improve the selectivity for “selective gene delivery” by high condensation of negatively charged plasmid DNA (pDNA) on the SWCNT walls .
The functionalized HiPCO® SWCNT-COOH mediates high water transport into a plant cell to enhance plant growth. The efficient transport of water molecules is attained by the smaller outer diameter of HiPCO® SWCNT that carries the water molecules(~0.28nm) into the pores found in the cell wall (2 – 20 nm), where the ions and water are transported through the plant cell wall .
NoPo produces single-walled carbon nanotubes (SWCNTs) using the HiPCO® process which afford high aspect ratio (up to 3000) SWCNTs with a narrow diameter distribution of 0.6-1.0nm.
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