Research

Bacterial flagellar motor

Rotation around an axis is not generally found in living systems. The flagellar motor is one striking exception. Found in the membrane of many bacteria, it actively rotates each flagellum at the base of which it is assembled. Being able to reach KHz rotation rates, this biological (electric) nano-motor, considering its size, is one of the most powerful motors in nature. Using our single-molecule manipulation and detection techniques, we aim to further investigate torque generation and angular dynamics of the motor, in order to elucidate the functioning of its internal components and its mechano-chemical cycle. More details here.

high-res. Photonic Force microscope

Near-field imaging techniques reach sub-nanometer resolution on rigid samples, but it's still challenging to image soft interfaces, such as biological membranes, due to the deformations induced by the probe. In photonic force microscopy, optical tweezers are used to manipulate and measure the scanning probe, allowing imaging of soft materials without force-induced artifacts. However, the size of the optically trapped probe still limits the maximum resolution. We have developed a novel and simple nanofabrication protocol to massively produce optically trappable quartz particles which mimic the sharp tips of atomic force microscopy. More details here.

Optical Torque Wrench

In standard optical tweezers, particles are trapped in x, y, z within the tight focus of a laser. The trapped particle can be used as a handle to bridge linear forces down to the nm scale, and to manipulate by tension single molecules like DNA or molecular motors. We use nano-fabricated birefringent nano-particles, shaped as cylinders, optically trapped by a linearly polarized laser. In this way we can measure not only the force but also the optical torque acting on the trapped particle, and on the molecule tethered to it. We aim to further develop this novel technique to open new applications in single-molecule manipulation. More details here.

Fast bead tracking and magnetic tweezers

Angular and linear manipulation of microscopic magnetic beads is possible in magnetic tweezers, a very valuable tool for experiments at the single-molecule level. We have developed a new illumination scheme (based on a semiconductor laser driven by a varying current), which allows tracking of the magnetic beads below one microsecond exposure time of the fast CMOS camera. This allows us to follow fast dynamics revealed by the motion of small beads, and track extremely fast events in the micron range.

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