Ryuji Yokokawa

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Artificial nanotransport systems inspired by intracellular transport processes have been investigated for over a decade using the motor protein kinesin and microtubules. However, only unidirectional cargo transport has been achieved for the purpose of nanotransport in a microfluidic system. Here, we demonstrate bidirectional nanotransport by integrating(More)
Intracellular cargo is transported by multiple motor proteins. Because of the force balance of motors with mixed polarities, cargo moves bidirectionally to achieve biological functions. Here, we propose a microtubule gliding assay for a tug-of-war study of kinesin and dynein. A boundary of the two motor groups is created by photolithographically patterning(More)
We present experiments and theory of a constant flow-driven microfluidic oscillator with widely tunable oscillation periods. This oscillator converts two constant input-flows from a syringe pump into an alternating, periodic output-flow with oscillation periods that can be adjusted to between 0.3 s to 4.1 h by tuning an external membrane capacitor. This(More)
Self-switching microfluidic circuits that are able to perform biochemical experiments in a parallel and autonomous manner, similar to instruction-embedded electronics, are rarely implemented. Here, we present design principles and demonstrations for gravity-driven, integrated, microfluidic pulsatile flow circuits. With a common gravity head as the only(More)
Despite the benefits of miniaturized devices, handling of tiny amount of molecules became a great challenge. Direct transport, similar to the one in intracellular transport, is a way to cope with the problem of transporting tiny amount of materials. Using motor proteins, i.e. kinesin, and the corresponding rail structures, i.e. microtubules, provides(More)
The motor protein dynein was introduced into a nanotransport system. We oriented microtubules by their polarity, and immobilized them based on a dynein-microtubule gliding assay system. This system achieved unidirectional transport of kinesin-coated microbeads. In contrast to conventional kinesin-based orientation systems, the dynein-based system allowed(More)
The Escherichia coli RuvB hexameric ring motor proteins, together with RuvAs, promote branch migration of Holliday junction DNA. Zero mode waveguides (ZMWs) constitute of nanosized holes and enable the visualization of a single fluorescent molecule under micromolar order of the molecules, which is applicable to characterize the formation of(More)
Microtubules driven by kinesin motors have been utilised as "molecular shuttles" in microfluidic environments with potential applications in autonomous nanoscale manipulations such as capturing, separating, and/or concentrating biomolecules. However, the conventional flow cell-based assay has difficulty in separating bound target molecules from free ones(More)
A novel microfabrication method of lead-free piezoelectric sodium potassium niobate [(K,Na)NbO 3 , KNN] thin films was proposed, and the piezoelectric characteristics of the KNN microactuators were evaluated. The KNN thin films were directly deposited on microfabricated Si microcantilevers. The transverse piezoelectric coefficient d 31 of the KNN films was(More)