Highly Dispersible Buckled Nanospring Carbon Nanotubes for Polymer Nano Composites.

We propose the unique structure of highly dispersible single-walled carbon nanotubes (SWCNTs) in various solvents and polymers using the ZnO nano particle template. Buckled nanospring-shaped carbon nanotubes (NS-CNTs) were synthesized by a chemical reaction of ZnO nanoparticles with acid-treated SWCNTs and then dissolving ZnO through chemical etching. The unique structure of distorted hexagonal NS-CNTs encircled around ZnO nanoparticles was formed by the bending of SWCNTs caused by the agglomeration of chemically adsorbed Zn(OH)2, which is further crystallized as the polycrystalline ZnO inner core. The highly dispersible NS-CNTs could be incorporated in the poly[(vinylidenefluoride-co-trifluoroethylene] [P(VDF-TrFE)] copolymer, one of widely studied ferro- and piezo-electric polymer, up to the value of 15 wt% as nanofillers. The relative dielectric constant (K) of polymer nanocomposite, at 1 kHz, was greatly enhanced from 12.7 to the value of 62.5 at 11 wt% of NS-CNTs, corresponding to a 492% increase compared to that of pristine P(VDF-TrFE) with only a small dielectric loss tangent (D) of 0.1.

Droplet-based magnetically activated cell separation.

In this study, we developed a method that target cells in suspension can be separated by combining magnetic force and gravitation force. Since the newly developed method involves a separating process of a droplet containing nontarget cells in suspension by applying magnetic force to separate target cells, we called it droplet-based magnetic activated cell sorting (dMACS). To demonstrate the efficiency of the dMACS system, Ter119 (+) cells from mouse bone marrow cells were separated by both conventional MACS and our dMACS systems. Effects of three parameters on separation efficiency were examined in the dMACS system. As a result, both volume of droplet of cell suspension, and magnetic force did not affect the efficiency of cell separation markedly. However, the time for cell settlement in the droplet showed a critical role in the efficiency of cell separation according to increasing time. Therefore, we tried to verify that the saturation time affected increase of its efficiency and that flow rate injected to get rid of the negative cell resulted in the decrease of its efficiency. Using this dMACS system, we were able to pinpoint that the flow rate of cell suspension injected into a magnetic platform results in disturbance in the droplet, leading to turbulence in the cell suspension.