Regensburg 2004 – scientific programme

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AKB: Biologische Physik

AKB 50: Poster Session "Biological Physics"

AKB 50.15: Poster

Friday, March 12, 2004, 10:30–13:00, B

Probing a Biomimetic Model of the Actin Cortex with Dynamic Holographic Optical Tweezers — •Christian Schmitz, Jennifer Curtis, and Joachim Spatz — Biophysikalische Chemie, Institut für Physikalische Chemie, Universität Heidelberg

The actin cortex is an adaptive chemo-mechanical polymer network located beneath the cell membrane. A thin, quasi two-dimensional (2D) network, the actin cortex plays a leading role in controlling cellular viscoelasticity, shape, and motility. Regulated by internal and external stimuli, the actin cortex varies its properties with controlled reversible polymerisation of actin. We construct a freely-floating 2D biomimetic actin network to address key questions such as what are the viscoelastic properties of a 2D actin network, and how are these mechanical properties modified by active, biochemical components like molecular motors. The actin network is arranged and probed using holographic optical tweezers, which produce and independently steer one to hundreds of optical traps. Using a bed of optical traps, microspheres are arranged into a geometric array onto which actin is deposited or grown. The tweezers coordinatively exert distorting forces on the network and when calibrated, they measure the response of the network at each microsphere.