On-Demand Ligand-Base DNA Sensor with Electrochemical Impedance Spectroscopy.

We have developed a DNA sensor that can be finalized to detect a specific target on demand. The electrode surface was modified with 2,7-diamino-1,8-naphthyridine (DANP), a small molecule with nanomolar affinity for the cytosine bulge structure. The electrode was immersed in a solution of synthetic probe-DNA that had a cytosine bulge structure at one end and a complementary sequence to the target DNA at the other end.

Electrochemical Impedimetric Real-Time Polymerase Chain Reactions Using Anomalous Charge Transfer Enhancement.

We developed a new electrochemical impedimetric method for the real-time detection of polymerase chain reactions (PCR) based on our recent discovery that the DNA intercalator, [Ru(bpy)DPPZ], anomalously enhances charge transfer between redox mediators, K[Fe(CN)]/K[Fe(CN)], and a carbon electrode. Three mM [Fe(CN)] and 5 μM [Ru(bpy)DPPZ] were added to the PCR solution, and electrochemical impedance spectroscopy (EIS) measurements were performed at each elongation heat cycle. The charge transfer resistance (Rct) was initially low due to the presence of [Ru(bpy)DPPZ] in the solution.

Anomalous Enhancement of Electrochemical Charge Transfer by a Ru Complex Ion Intercalator.

We have found that the DNA intercalator [Ru(bpy)DPPZ] (bpy = 2,2'-bipyridine; DPPZ = dipyrido[3,2-:2',3'-]phenazine) causes an anomalous increase in charge transfer in electrochemical impedance spectroscopy (EIS). With a carbonaceous electrode and a 1 mM hexacyanoferrate (1 mM [Fe(CN)] and 1 mM [Fe(CN)]) mediator, we found that adding only 1 μM [Ru(bpy)DPPZ] greatly enhanced the charge transfer between the electrode and hexacyanoferrate mediator, independently of other electrolytes or buffer components. The effect started with a one millionth amount of hexacyanoferrate.

Dispersed Gold Nanoparticle Array Produced by Apoferritins Utilizing Biomineralization and Chemical Conversion.

A new method for producing a dispersed gold nanoparticle (Au NP) array to anchor probe DNAs onto a DNA-sensing electrode has been developed. A homogenous gold sulfide (AuS) core (precursor of Au NP) was biomineralized in the cavity of a mutant apoferritin (K98E) with enhanced negative outer-surface charges. We employed a slow chemical reaction system utilizing a stable cationic gold complex.

Water Solubilization of Fullerene Derivatives by β-(1,3-1,6)-d-Glucan and Their Photodynamic Activities toward Macrophages.

Anionic and neutral fullerene derivatives were dissolved in water by using β-(1,3-1,6)-d-glucan (β-1,3-glucan) as a solubilizing agent. In the water-solubilized complexes, the concentrations of fullerene derivatives were ≈0.30 mm and the average particle sizes were ≈90 nm.

Synthesis and Properties of [7]Helicene-like Compounds Fused with a Fluorene Unit.

[7]Helicene-like compounds with a fluorene unit were successfully synthesized using a platinum-catalyzed double cyclization reaction. Crystal structures and photophysical properties of these compounds were also studied. In particular, they were found to exhibit a high fluorescence quantum yield and a relatively large g value (dissymmetric factor) of circularly polarized luminescence (CPL) for small molecules.

[70]Fullerenes assist the formation of phospholipid bicelles at low lipid concentrations.

The incorporation of neutral [70]fullerenes (C70) led to bicelle formation in a relatively low lipid concentration range from neutral lipid mixtures (DMPC/DHPC). Furthermore, C70 addition resulted in the formation of large bicelles with a radius of ca. 100 nm, in contrast to C70-free bicelles that were formed from anionic lipid mixtures (DMPC/DHPC/DMPG).

Pyridyl-cyclodextrin for ultra-hydrosolubilization of [60]fullerene.

An efficient hydrosolubilizing reagent for [60]fullerene (C60) was newly developed with a γ-cyclodextrin (γ-CD) derivative having triazole-methoxypyridyl moieties at its 6-hydroxyl positions (PCD). Through solid-state mechanochemical complexation, PCD forms a hydrosoluble inclusion complex of C60 with a concentration of more than 70 mM. This is approximately 90 times greater than that with non-substituted γ-CD prepared by the same method.

NMR spectroscopic study of the complexation behaviors of deuterated cyclodextrins and [60]fullerene.

Cyclodextrins (CDxs) have been selectively deuterated using a Ru/C-catalyzed H-D exchange reaction in D2O. The structures of the deuterated CDxs barely changed and their (1)H NMR spectra became very simple, which made it possible for the deuterated CDxs to be applied to the analysis of CDx complexes. Furthermore, the deuterated CDxs allowed for the existence of the equilibrium between free and complexed CDx to be confirmed, even at rt.

Facile synthetic route to highly luminescent sila[7]helicene.

A facile synthetic route to dimethylsila[7]helicene by using a Lewis acid catalyzed double-cyclization reaction for construction of the twisted two phenanthrene moieties is described. Sila[7]helicene exhibited a high fluorescence quantum yield and a realatively large g value (dissymmetric factor) of circularly polarized luminencence (CPL) for small molecules.

Time-resolved observation of chiral-index-selective wrapping on single-walled carbon nanotube with non-aromatic polysilane.

In the present paper, we ascertain two novel findings on chiral-index-selective binding/separating of single-walled carbon nanotubes (SWNTs) with a nonaromatic polymer, poly(dialkylsilane) (PSi). PSi is a typical σ-conjugated polymer, composed of alkyl side chains attached to the silicon (Si)-catenated main chain. First, PSi's with linear alkyl side chains showed significant diameter-selective wrapping for SWNTs with ca.

Advantages and potential of lipid-membrane-incorporating fullerenes prepared by the fullerene-exchange method.

Lipid-membrane-incorporating C(60) and C(70) (LMIC(60) and LMIC(70)) were prepared by the fullerene-exchange reaction from the γ-cyclodextrin cavity to vesicles (we call this method the "exchange method"). An advantage of this method is that the ratios of [C(60)]/[lipids] and [C(70)]/[lipids] can be arbitrarily controlled by adjusting the ratios of the fullerenes and liposome. The maximum ratio (30 mol%) obtained was approximately 14 and 100 times higher than those achieved for LMIC(60) and LMIC(70) , respectively, that were prepared by the classical method, which we call the "premixing method" (dissolving lipids and C(60) or C(70) in chloroform, followed by concentration and extraction with water).

Location of [60]fullerene incorporation in lipid membranes.

We confirmed that most C(60) fullerene units are located in the hydrophobic core of the lipid bilayer membrane in water-soluble lipid membrane incorporated C(60) (LMIC(60)) complexes using differential scanning calorimetry (DSC) and (13)C NMR spectra in the presence of radical labels.

Chemical-stimuli-controllable circularly polarized luminescence from anion-responsive π-conjugated molecules.

Introduction of a BINOL-boron moiety to dipyrrolyldiketones as precursors of anion-responsive π-conjugated molecules results in the formation of a chiral environment in the form of anion-free receptors and anion-binding complexes. Conformation changes by inversion (flipping) of two pyrrole rings as a result of anion binding can control the chiroptical properties of the anion receptors. In particular, appropriate pyrrole β-substituents induce distorted receptor π-planes and, as a result, give larger circularly polarized luminescence (CPL), which can be tuned by chemical stimuli (anions).

Stiffness- and conformation-dependent polymer wrapping onto single-walled carbon nanotubes.

This work reports the effect of stiffness and conformation of chain-like polymers on wrapping behaviors around single-walled carbon nanotubes (SWNT). As a model of chain-like polymers, three kinds of poly(dialkylsilane) (PSi)s with random-coiled, flexible, and semiflexible main chains were employed. Complexes of PSi and SWNT were prepared using mechanochemical high-speed vibration milling (HSVM).

Angle-controlled arrangement of single-walled carbon nanotubes solubilised by 8-quinolinol metal chelate derivatives on mica.

We solubilised SWNTs of short length using a mechanochemical high-speed vibration milling (HSVM) through formation of complexes between the SWNTs and chelate complexes; the mixture formed a network structure on mica.

Solubilization of single-walled carbon nanotubes by supramolecular complexes of barbituric acid and triaminopyrimidines.

In this letter, we report that single-walled carbon nanotubes (SWNTs) can be dissolved in organic solvents through the formation of admixtures with barbituric acid.triaminopyrimidine (BA.TP) complexes using mechanochemical high-speed vibration milling (HSVM) and sonication methods.

Single-walled carbon nanotubes template the one-dimensional ordering of a polythiophene derivative.

We have used a mechanochemical high-speed vibration milling (HSVM) technique to solubilize single-walled carbon nanotubes (SWNTs) in organic solvents through the formation of complexes between the SWNTs and a polythiophene (PT) derivative. This HSVM approach is superior to the conventional sonication method used to solubilize SWNTs in organic solvents. Moreover, we found that in these supramolecular complexes the PT chains were ordered one-dimensionally on the SWNT surfaces in organic solvents.