科研之友
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摘要
The studies on the nucleic acid structure and the interactions between nucleic acid and its binding molecules are of great importance for the understanding and controlling of many important biological processes. Atomic force spectroscopy (AFM) imaging is one of the most efficient methods to disclose the DNA structure and binding modes between DNA and DNA-binding molecules. Long-chain DNA tends to form a random coiled structure, which prevents the direct AFM imaging observation of subtle structure formed by DNA itself or protein binding. Aligning of DNA from the random coiled state into the extended state is not only important for applications in DNA nanotechnology, but also for elucidating the interaction mechanism between DNA and other molecules. Here, we developed an efficient method based on magnetic field to align long-chain DNA on the silicon surface. We used AFM imaging to study the alignment of DNA at the single-molecule level. It turned out the DNA can be stretched and highly aligned by the manipulation of magnetic nanoparticles tethered to one end of DNA, and the aligned DNA can be imaged clearly by AFM. In the absence of the magnetic field, the aligned DNA can relax back to a random coiled state upon rinsing. Such alignment and relaxation can be repeated for many times, which provides an efficient way for the manipulation of individual DNA molecule and the investigation of DNA and DNA-binding molecule interactions.
