Formation of microcraters on plant cell wall by plasma immersion ion implantation

Ion bombardment of biological cellular material has been used as a tool for the transfer of exogenous DNA macromolecules into the cell interior region. The precise physical mechanisms associated with this transfer of macromolecules through the cell envelope remain unexplained, however it has been observed that the ion bombardment is accompanied by the formation of “microcraters” on the wall of plant cells, and it is possible that these features provide channels for the macromolecule transfer. Thus the nature and origin of the microcraters are of importance to understanding the DNA transfer phenomenon as well as being of fundamental interest. We report here on the formation of microcraters on onion skin cell walls by plasma immersion ion implantation (PIII) using ~ 20 keV Ar+ ions at a dose of about 1 × 1015 ions/cm2. The results indicate that PIII provides a tool for carrying out ion bombardment of living biological materials previously done using beam-line implantation methods.