Right- / left-circular orientation of biological macromolecules under magnetic field gradient

In spite of many studies on phase behaviors and orientational phenomena of biological marcomolecular suspensions under magnetic field, a translational force from magnetic field gradient was paid less attention. We have developed a high-performance compact magnetic circuit that can apply both periodic magnetic field strength and gradient to samples. Owing to the periodicity of the magnetic field strength and gradient, macromolecules are subject to both rotational and translational forces from magnetic field. By using this magnet, we have carried out time-resolved small-angle X-ray scattering measurements on an orientational behavior of a biological supermolecular suspension under periodic magnetic field and gradient. The sample was tobacco mosaic virus (TMV) which is one of rod-shaped plant viruses. The time courses of the orientational processes of TMV were monitored by a two-dimensional CCD detector. We have found that right-circular or left-circular orientation of TMV appears depending on a combination of magnetic field and gradient directions. Such a translational force from magnetic field gradient is able to cause various interesting phenomena of macromolecular systems, which would be applicable to a control of nano-scale assembling processes of macromolecules.