Effects of sticky ends
Japanese scientists have investigated the self-assembled synthesis of DNA nanostructures using direct observation of charge transfer kinetics. Tetsuro Majima, Kiyohiko Kawai and colleagues from Osaka University made photosensitizer modified and charge acceptor modified DNA with different lengths of 'sticky end'.
Sticky ends are single strand sections of DNA which 'work as glue' for nanostructure assembly. Majima and colleagues investigated the effects of changing the length of sticky ends on the assembly of nanostructures, by direct observation of the charge transfer kinetics.
Charge transfer has been shown previously to occur between strands through adenine to its paired guanine, and along strands by guanine hopping. The charge transfer should therefore not occur between unattached segments. After exciting the photosensitizer modified DNA via laser, they watched for the charge acceptor to form a radical cation to indicate assembly. Formation of the radical cation occurred at 590 nm.
The major challenge in this area for the future is to examine the conductivity of DNA nanostructures according to Majima. The next step in their lab will be to investigate the charge transfer in DNA segments constructed by cross-over DNA.
Original publication: Y. Osakada et al, Chem. Commun., 2008.
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