A micromachined DNA manipulation platform for the stretching and rotation of a single DNA molecule

A micromachine-based DNA manipulation platform for stretching and rotation of a single DNA molecule is reported. The DNA molecule with a 2 nm diameter could be successfully manipulated using magnetic forces generated by arrayed microcoils fabricated by MEMS (micro-electromechanical systems) technology. Key platform technologies including localized DNA immobilization, microcoil fabrication and microfluidics, have been integrated to form the DNA magnetic tweezers. One end of a single DNA molecule is specifically bonded onto a magnetic bead and the other end onto a gold surface. It is then manipulated under a magnetic field generated by built-in hexagonally aligned microcoils. Design and simulation of the magnetic tweezers are carried out by using numerical software. A highly effective and strong binding method for the construction of two sticky ends of a DNA is developed, which is compatible with MEMS technologies. To quantify the magnitude of magnetic forces acting on the DNA, force calibration is performed and further verified by the worm-like chain (WLC) model. The measured DNA stretching forces are found to be in reasonable agreement with the theoretical values. We have successfully demonstrated the stretching and rotation of the tethered-bead DNA molecule linked to a gold pattern using the developed method. The spring constant of the DNA molecule is experimentally found to be about 10(-8)-10(-7) N m(-1). The development of the proposed method could be useful for investigation of DNA biophysical properties.