Development of Amylose- and β-Cyclodextrin-Based Chiral Fluorescent Sensors Bearing Terthienyl Pendants

Phenylcarbamate derivatives of amylose and β-cyclodextrin show excellent chiral recognition when used as chiral stationary phases (CSPs) for high-performance liquid chromatography. To open up new possibilities of carbohydrate-based materials, we developed chiral fluorescent sensors based on amylose and β-cyclodextrin (Am-1b and CyD-1b, respectively) by attaching fluorescent π-conjugated units on their side chains. Their recognition abilities toward chiral analytes containing a nitrophenyl unit were evaluated by measuring the enantioselective fluorescence quenching behavior. Both sensors showed the same degree of enantioselective fluorescence response for various aromatic nitro compounds. However, in some cases, their enantioselectivities were different depending on the analytes. The difference in the chiral recognition abilities between Am-1b and CyD-1b seems to be based on the structural difference of their inherent backbones, that is, the one-handed helical structure and cyclic structure, respectively. The study on the resolution ability of the Am-1b-based CSP revealed that the terthienyl-based pendant of Am-1b provides not only a fluorescent functionality but also a different chiral recognition site from that of amylose tris(phenylcarbamate)

Chemically Driven, Water-Soluble Composites of Carbon Nanotubes and Silver Nanoparticles as Stretchable Conductors

In the past decade, hybrid materials for highly stretchable, conductive electrodes have received tremendous attention in the fields of emerging wearable electronic, optoelectronic, and sensing devices. Here, we present a previously unrecognized aqueous route to producing stretchable conductors composed of silver nanoparticles (AgNPs) and single-walled carbon nanotubes (SWNTs) embedded in a polyurethane (PU) matrix, in contrast to ones dispersed in toxic organic solvents reported to date. The intact chemical interaction between one-dimensional SWNTs, for endowing the capability of establishing conductive pathways even in stretching conditions, and AgNPs, for enabling high conductivity of the composites, is achieved in an aqueous medium with an anionic polyelectrolyte, poly­(acrylic acid), that undergoes pH-dependent conformational evolution. With this aqueous approach, we demonstrate that AgNP–SWNT–PU composites supported on PDMS substrates have the conductivities of 620 and 120 S cm^–1 in unstrained and 90% elongated conditions, respectively, and display repeatable reversibility at a strain of 60%

Long dsRNA-Mediated RNA Interference and Immunostimulation: A Targeted Delivery Approach Using Polyethyleneimine Based Nano-Carriers

RNA oligonucleotides capable of inducing controlled immunostimulation combined with specific oncogene silencing via an RNA interference (RNAi) mechanism provide synergistic inhibition of cancer cell growth. With this concept, we previously designed a potent immunostimulatory long double stranded RNA, referred to as liRNA, capable of executing RNAi mediated specific target gene silencing. In this study, we developed a highly effective liRNA based targeted delivery system to apply in the treatment of glioblastoma multiforme. A stable nanocomplex was fabricated by complexing multimerized liRNA structures with cross-linked branched poly­(ethylene imine) (bPEI) via electrostatic interactions. We show clear evidence that the cross-linked bPEI was quite effective in enhancing the cellular uptake of liRNA on U87MG cells. Moreover, the liRNA-PEI nanocomplex provided strong RNAi mediated target gene silencing compared to that of the conventional siRNA-PEI complex. Further, the bPEI modification strategy with specific ligand attachment assisted the uptake of the liRNA-PEI complex on the mouse brain endothelial cell line (b.End3). Such delivery systems combining the beneficial elements of targeted delivery, controlled immunostimulation, and RNAi mediated target silencing have immense potential in anticancer therapy

Selective dispersion of single-walled carbon nanotubes by binaphthyl-based conjugated polymers: Integrated experimental and simulation approach

Hybrids of ??-conjugated polymers and single-walled carbon nanotubes (SWNTs) are an intriguing class of materials owing to their interesting electric and optoelectronic properties. Herein, we synthesized three types of 1,1???-binaphthyl-incorporated conjugated polymers with thiophene bridges. It was found that the molecular structure of the ??-conjugated polymers affected the selective dispersion of individual SWNT species: the hexyl-substituted PBHT preferred (8,7) SWNT while polymers with no alkyl groups on the thiophenes (PBT and PB2T) preferred (8,6) species. Molecular dynamics (MD) simulations also revealed that the polymers were able to wrap around SWNTs and showed selective interactions with the SWNT species.clos