DNA-Assisted Molecular Delivery

Many examples have been reported of assembly of atoms and small molecules into patterns on surfaces by pick up, transfer, and release with a scanning probe microscope tip under vacuum conditions. Kufer et al. assembled larger single molecules into patterns on surfaces in aqueous solution with an atomic force microscope (AFM) tip by taking advantage of differential forces acting on double-stranded DNA. "Depots" and "target" areas containing single-stranded (ss) 30-nucleotide (nt) DNAs were patterned onto glass slides, and then ssDNAs bearing the complementary sequence, a 20-nt "shear" sequence, and an organic dye molecule were attached to the depot area. An AFM tip bearing the complementary shear sequence could pick up DNAs from the depot area and then deposit them in the target area with a precision of ~ 10 nanometers. Measurement of the rupture forces differentiates single from multiple or zero DNA transfers and ensures the fidelity of delivery, which could be repeated up to 5000 times.


Sources:

Single-Molecule Cut-and-Paste Surface Assembly. Kufer et al. Science 1 February 2008: Vol. 319. no. 5863, pp. 594 - 596.