APPLICATIONS OF ELECTROSTATIC STRETCH-AND-POSITIONING OF DNA

The authors have previously reported that the electrostatic orientatio n and the dielectrophoresis (DEP) of DNA occur under approximate to 1 MHz, > 1 x 10(6) V/m field, by which DNA strands are stretched straigh t along field lines and positioned onto electrode edges, This paper pr esents some application of this stretch-and-positioning method to gene tic engineering, It is shown that the DNA size distribution, as well a s the activities of nuclease, can be determined by the measurement of the apparent length of stretched DNA. Several methods are developed to immobilize stretched DNA onto a substrate, including: 1) immobilizati on onto a conducting substrate for observations with the scanning tunn eling microscopy, 2) anchoring onto a substrate only at the both ends of DNA using special electrode configuration, and/or molecular binding between avidin and biotin, The DNA can be held without contact to the substrate in the latter method, so that it does not cause steric hind rances to the DNA-binding enzymes. A novel Fluid Integrated Circuit (F IC) device is proposed in which stretched DNA is cut by laser beam for the successive sequencing. A method to obtain unidirectionally orient ed DNA is developed. The spatial resolution, and the small number of m olecules required, are the advantages of the assays and measurements u sing electrostatic DNA manipulations over conventional biochemical met hods. It is hoped that the methods may open a way to a novel category of ''molecular biochemistry with spatial resolution.''