Protein molecules produce diverse functions according to their combination and arrangement as is evident in a living cell. Therefore, they have a great potential for application in future devices. However, it is currently very difficult to construct systems in which a large number of different protein molecules work cooperatively. As an approach to this challenge, we arranged protein molecules in artificial microstructures and assembled an optical device inspired by a molecular system of a fish melanophore. We prepared arrays of cell-like microchambers, each of which contained a scaffold of microtubule seeds at the center. By polymerizing tubulin from the fixed microtubule seeds, we obtained radially arranged microtubules in the chambers. We subsequently prepared pigment granules associated with dynein motors and attached them to the radial microtubule arrays, which made a melanophore-like system. When ATP was added to the system, the color patterns of the chamber successfully changed, due to active transportation of pigments. Furthermore, as an application of the system, image formation on the array of the optical units was performed. This study demonstrates that a properly designed microstructure facilitates arrangement and selforganization of molecules and enables assembly of functional molecular systems.bioengineering | microdevice | molecular robotics W ithin a cell, motor proteins work as mechanical components that efficiently convert chemical energy to mechanical energy. Major motor proteins, such as myosin, kinesin, and dynein, travel unidirectionally along specific filamentous protein polymers, actin filaments, or microtubules, using the chemical energy derived from ATP. Although the action of motor proteins itself is rather simple, they are involved in numerous functions in living cells such as cell division, muscle contractions, ciliary beating, and melanophore color changes (1). These diverse and elaborate functions are realized through highly ordered molecular systems that consist of not only the motor proteins but also various types of protein molecules. For example, myosin and actin form alternatively arranged bundles with tens of other proteins to construct aligned sarcomeres, the basic units of the muscle, which produce efficient contractions under strict Ca 2+ regulation (1). Likewise, in the cilium or flagellum, dynein molecules are integrated into the "9 + 2" arrangement of microtubules and generate oscillatory bending (1). Thus, diversity of in vivo functions of motor proteins is achieved by the variety of manners in which motor proteins are organized into specific higher order systems.In the last decade, remarkable progress has been made in the applications of motor proteins in microscale and nanoscale engineering, which has enabled the control of motor protein movements and the transport of artificial objects by motor protein (2-14). These microtransportation systems are expected to be a shuttle for micrototal analysis systems and other simple tools (15)(16)(17). To fully use the potential...

In single molecule force measurements with soft atomic force microscope (AFM) cantilevers, the force sensitivity is limited by the Brownian motion of the cantilever. When a cantilever is close to the surface, the hydrodynamic interaction between the cantilever beam and the surface, called the “squeezing effect”, becomes significant, and the resonance peak of the thermal oscillation of the cantilever is heavily broadened and shifted to lower frequency which makes it difficult to eliminate the thermal noise by low-pass filtering. In this study, we propose an easy and low-cost method to improve the force sensitivity. We demonstrate that by bringing a tip of a cantilever onto the edge of a micropillar structure a significant reduction of the damping and an enhancement of force sensitivity are achieved.

guidrng track metif 1ias to be Larefully designed and piepared HowevLr the design ot the guiding tracks is depending on enginee"ng mtuinons aMd experimental trial and errorTo enable rational design ot the M mobile guidrng tracks "e are aiming at developmg a computer gimulation tLehniqut whiLh rcrproduLes iVf mobtte cell movements on the geuding tracks To this end, we prevlously reported statisucal alldlyses of M mobile cell movements on surfices without rmcrofabmcated tracks HerL, to modLl M mohite cell moverncnts on m]Lrofabm"dted trdLks wL preparLd substrdtes wnii mierofabnLated posts "hose rad" wLrL

No abstract

No abstract