manipulating-living-cells-to-construct-stable-3d-cellular-assembly

Manipulating Living Cells to Construct Stable 3D Cellular Assembly Without Artificial Scaffold

Regenerative medicine and tissue engineering offer several advantages for the treatment of intractable diseases, and several studies have demonstrated the ...

Doshisha University

Two (ONO pincer)ruthenium-complex-bound norvalines, Boc-[Ru(pydc)(terpy)]Nva-OMe (1; Boc=tert-butyloxycarbonyl, terpy=terpyridyl, Nva=norvaline) and Boc-[Ru(pydc)(tBu-terpy)]Nva-OMe (5), were successfully synthesized and their molecular structures and absolute configurations were unequivocally determined by single-crystal X-ray diffraction. The robustness of the pincer Ru complexes and norvaline scaffolds against acidic/basic, oxidizing, and high-temperature conditions enabled us to perform selective transformations of the N-Boc and C-OMe termini into various functional groups, such as alkyl amide, alkyl urea, and polyether groups, without the loss of the Ru center or enantiomeric purity. The resulting dialkylated Ru-bound norvaline, n-C11 H23 CO-l-[Ru(pydc)(terpy)]Nva-NH-n-C11 H23 (l-4) was found to have excellent self-assembly properties in organic solvents, thereby affording the corresponding supramolecular gels. Ru-bound norvaline l-1 exhibited a higher catalytic activity for the oxidation of alcohols by H2 O2 than parent complex [Ru(pydc)(terpy)] (11 a). 

Synthesis and Applications of (ONO Pincer)Ruthenium-Complex-Bound Norvalines.

We observed single DNA molecules at different ethanol concentrations by using fluorescence microscopy. Large single DNA molecules undergo reentrant conformational transitions from elongated coil into folded globule and then into elongated coil state, accompanied by the increase of the concentration of ethanol in a low-salt aqueous environment. The second transition from globule into the coil state occurs at around 70 % (v/v) ethanol. From circular dichroism (CD) measurements, it is confirmed that the reentrant transition of the higher order structure proceeds together with the transitions of the secondary structure from B to C and, then, from C to A in a cooperative manner. The determined mechanism of the reentrant transition is discussed in relation to the unique characteristics of solutions with higher ethanol content, for which clathrate-like nanostructures of alcohol molecules are generated in the surrounding water. 

Highly Concentrated Ethanol Solutions: Good Solvents for DNA as Revealed by Single-Molecule Observation.

Shape-oscillations and synchronization are intriguing phenomena in many biological and physical systems. Here, we report the rhythmic mechanical oscillations and synchronization of aniline oil droplets on a water phase, which is induced by Marangoni convection during transfer of the solute. The repetitive increase and decrease in the surface concentration in the vicinity of the contact line leads to the oscillations of droplets through an imbalance in surface tensions. The nature of the oscillations depends on the diameter of the droplet, the depth of the bulk aqueous phase, and the concentration of the aqueous phase. A numerical simulation reproduces the essential behaviors of active oscillations of a droplet. Droplets sense each other through a surface tension gradient and advection, and hydrodynamic coupling in the bulk solution induces the synchronization of droplet oscillations.

Spontaneous Oscillations and Synchronization of Active Droplets on a Water Surface via Marangoni Convection.

We report the successful generation of directional liquid-flow under stationary laser irradiation at a fixed position in a chamber. We adopt a homogeneous solution consisting of a mixture of water and triethylamine (TEA), with a composition near the critical point for phase segregation. When geometrical asymmetry is introduced around the laser focus in the chamber, continuous directional flow is generated, accompanied by the emergence of water-rich microdroplets at the laser focus. The emerging microdroplets tend to escape toward the surrounding bulk solution and then merge/annihilate into the homogeneous solution. The essential features of the directional flow are reproduced through a simple numerical simulation using fluid dynamic equations.

Article	Year
Synthesis and Applications of (ONO Pincer)Ruthenium-Complex-Bound Norvalines. Chemistry, an Asian journal\| PubMed ID: 26879368	2016
Highly Concentrated Ethanol Solutions: Good Solvents for DNA as Revealed by Single-Molecule Observation. Chemphyschem : a European journal of chemical physics and physical chemistry\| PubMed ID: 26891092	2016
Spontaneous Oscillations and Synchronization of Active Droplets on a Water Surface via Marangoni Convection. Langmuir : the ACS journal of surfaces and colloids\| PubMed ID: 28991482	2017
Optical Fluid Pump: Generation of Directional Flow via Microphase Segregation/Homogenization. The journal of physical chemistry letters\| PubMed ID: 30222363	2018

Koichiro Sadakane

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