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The anisotropic properties of one-dimensional (1D) supramolecules have generally been the sole way to input molecular information along a structure of high density. Although the chain reaction of a...

A series of porphyrin-curdlan conjugates 1-5 of varying degree of substitution (DS) were synthesized to examine their morphological features, chiroptical properties, and oligosaccharide sensing in aqueous media, particularly for tetrasaccharide acarbose, which is a drug to treat type-2 diabetes. The random coil state of compounds 1-5 in DMSO becomes the globule curdlan-saccharide coaggregate upon interaction of acarbose in aqueous DMSO solution to induce various circular dichroism (CD) responses. The high cooperativity and positive homotropic allosterism were observed in the acarbose recognition, enabling the allosteric signal-amplification sensing, for which the DS, stacking character, and microenvironmental polarity changes of the tethered porphyrin reporters are likely to be responsible.

Very rapid, uniform and vector diffusion of solvent molecules can be coupled with up-hill self-assembly from less active molecules and/or under low concentration conditions. We have demonstrated in this paper that perylene bisimide derivatives undergo effective supramolecular polymerization in microflow channels coupling with solvent diffusion. The resultant nanofibers were highly aligned along the stream line of laminar flow.

In a microflow environment, the sizes of guest-binding pockets constructed by chlorophyll units can be regulated precisely through linking to the spring-like dynamic motion of a polymer backbone. Very rapid host/guest interactions at the polymer surface enabled isolation of metastable conformers having different helical pitches.

Control over the self-assembly pathways of small functional molecules is a current trend in supramolecular chemistry, as a variety of metastable self-assemblies with nanostructures distinct from those of thermodynamically stable assemblies can be formed as kinetic products. If such kinetically formed assemblies can be trapped under non-equilibrium conditions, diverse self-organized structures beyond the immediate molecular design may be accessible. The self-assembly of specifically designed amphiphilic π-conjugated molecules in water represents a promising strategy to realize such conditions, wherein strong hydrophobic molecular interactions play an important role. Based on the alkyl-tethered covalent perylene bisimide (PBI) dyad scaffold that can potentially aggregate into one-dimensional supramolecular polymers, herein we demonstrate that an amphiphilic molecular design can open up new self-assembly pathways, which can potentially afford distinct nanostructures in aqueous media. We synthesized amphiphilic PBI dyads that contain one PBI unit functionalized with hydrophobic branched alkyl chains, and one PBI unit functionalized with hydrophilic branched alkyl chains. By changing the composition ratio of the THF/water mixtures, we obtained one-dimensional fibrous and vesicular aggregates as a result of increasing hydrophobic effects. Increasing the temperature of the THF/water mixtures in which fibrous aggregates are preferentially formed subdued the aggregation to entropy control and resulted in the formation of coil- and ring-shaped kinetic nanoaggregates.

Fine hydrogen-bonded networks over the micrometer scale were spontaneously constructed in microflow through the synchronized protonation of porphyrin having four carboxylic acid groups. The obtaine...

Constructing new and versatile self-assembling systems in supramolecular chemistry is much like the development of new reactions or new catalysts in synthetic organic chemistry. As one such new technology, conventional supramolecular assembly systems have been combined with microflow techniques to control intermolecular or interpolymer interactions through precise regulation of a flowing self-assembly field. The potential of the microflow system has been explored by using various simple model compounds. Uniform solvent diffusion in the microflow leads to rapid activation of molecules in a nonequilibrium state and, thereby, enhanced interactions. All of these self-assembly processes begin from a temporally activated state and proceed in a uniform chemical environment, forming a synchronized cluster and resulting in effective conversion to supramolecules, with precise tuning of molecular (or polymer) interactions. This approach allows the synthesis of a variety of discrete microstructures (e.g., fibers, sheets) and unique supramolecules (e.g., hierarchical assemblies, capped fibers, polymer networks, supramolecules with time-delayed action) that have previously been inaccessible.

This chapter focuses on dynamic polymer–polymer interactions triggered by the boronic acid–diol interaction. General polymer–polymer interactions, except for those occurring in biological systems, take place in a random fashion. In view of the creation of polymer based materials, any comprehensive strategy for overcoming this limitation would be attractive and applicable. By introducing boronic acid groups into a polymer, it acquires precise molecular recognition ability based on dynamic boronic acid–diol interactions, thus affording stimulus-responsive supramolecular architectures in combination with various molecules or polymers. This strategy is powerful and introduces new opportunities for the sciences of polymer-based materials.

We recently revealed that β-1,3-glucans act as unique natural nanotubes, which can accept functional polymers and molecular assemblies in an induced-fit manner. A variety of individual conjugated polymers or molecular assemblies can be incorporated into the one-dimensional hollow constructed by the helical superstructure of β-1,3-glucans to create water-soluble one-dimensional nanocomposites. The advantageous point of the present hosting system is that the selective modification of β-1,3-glucans leads to the creation of various functional one-dimensional nanocomposites in a supramolecular manner. Furthermore, the composites with functional surfaces can act as one-dimensional building blocks toward further hierarchical self-assembles, leading to the creation of two- or three-dimensional nanoarchitectures, which are applicable for fundamental nanomaterials.

It is known that an achiral water-soluble polythiophene (PT-1) is chirally twisted by complexation with a natural helix-forming polysaccharide, shizophyllan (SPG). We found that the chirality can b...

Much attention has been focused on exploiting novel strategies for the creation of hierarchical polymer assemblies by the control of the assembling number or the relative location among neighboring polymers. We here propose a novel strategy toward the creation of "hierarchical" single-walled carbon nanotube (SWNT) architectures by utilizing SWNT composites with cationic or anionic complementary semi-artificial beta-1,3-glucans as "building blocks". These beta-1,3-glucans are known to wrap SWNTs helically, to create one-dimensional superstructural composites. If the cationic composite is neutralized by an anionic composite, a well ordered SWNT-based sheet structure was created. Transmission electron microscopy (TEM) observation revealed that this sheet structure is composed of highly-ordered fibrous assemblies of SWNTs. This suggests that the cationic and anionic composites are tightly packed through electrostatic interactions. Moreover, both of the final assembly structures are readily tunable by adjusting the cation/anion ratio. The self-assembling modulation of functional polymers is associated with the progress in ultimate nanotechnologies, thus enabling us to create numerous functional nanomaterials. We believe, therefore, that the present system will extend the frontier of SWNT research to assembly chemistry including "hierarchical" superstructures.

It has been demonstrated that a chiral, insulated poly(p-phenylene ethynylene) (PPE) nano-wire can be created by a polymer wrapping method utilizing natural β-1,3-glucan polysaccharide schizophyllan (SPG). Spectroscopic and microscopic measurements have revealed that PPE adopts a rigid conformation and exists as one piece in the helical hollow constructed by two SPG chains. Moreover, the inherent helical structure of SPG can induce the chiral twisting of the insulated PPE backbone. It is believed that the present system is really applicable for designing novel chiral sensors based on PPE.

Constructing new and versatile self-assembling systems in supramolecular chemistry is much like the development of new reactions or new catalysts in synthetic organic chemistry. As one such new technology, conventional supramolecular assembly systems have been combined with microflow techniques to control intermolecular or interpolymer interactions through precise regulation of a flowing self-assembly field. The potential of the microflow system has been explored by using various simple model compounds. Uniform solvent diffusion in the microflow leads to rapid activation of molecules in a nonequilibrium state and, thereby, enhanced interactions. All of these self-assembly processes begin from a temporally activated state and proceed in a uniform chemical environment, forming a synchronized cluster and resulting in effective conversion to supramolecules, with precise tuning of molecular (or polymer) interactions. This approach allows the synthesis of a variety of discrete microstructures (e.g., fibers, sheets) and unique supramolecules (e.g., hierarchical assemblies, capped fibers, polymer networks, supramolecules with time-delayed action) that have previously been inaccessible.

We have demonstrated that one-dimensional supramolecular dye assemblies with a uniform diameter can be created by utilizing schizophyllan (SPG) as a one-dimensional host. In the supramolecular nanofibers, the dye molecules are assembled into the different aggregation modes depending on the preparation procedures. The findings establish that SPG is useful for creating the supramolecular nanofibers, where temporal superstructures can be stabilized by the SPG-specific helical higher-order structure. [structure: see text].

(1→3)-β- d -Glucans having various functional appendages (lactoside, ferrocene, pyrene, and porphyrin) can be prepared in an convenient, quantitative, and regioselective manner through regioselective bromination–azidation of curdlan to afford 6-azido-6-deoxycurdlan followed by chemoselective [3+2]-cycloadditions with various functional modules bearing a terminal alkyne group. The ability to monitor reaction conversions is an additional advantage of this synthetic approach over the conventional direct modifications on polysaccharides; the reaction can be readily monitored based on the intensity of azido peaks in the in situ attenuated total reflection infrared spectra.

It was found that DNAs can act as attractive templates for oxidative polymerization of pyrrole and result in novel higher-order superstructures composed of the DNA padding and the conjugate polymer outer layer. Furthermore, the resultant DNA/poly(pyrrole) composite can be deposited on an ITO electrode. The TEM and SEM observations have shown that oxidative polymerization creates a variety of superstructural poly(pyrrole) assemblies such as nanosized rodlike, circular, or supercoiled structures, reflecting the higher-order conformations of DNAs acting as the templates. The findings establish that the morphology of the conjugate polymer assemblies are controllable by a change in the DNA morphology used as their templates. The deposition of DNAs onto the ITO electrode was characterized by (1) ATR IR absorption bands assignable to DNA, (2) XPS binding energy of the phosphate group assignable to DNAs, and (3) binding of ethidium bromide (EB) to DNAs as detected by UV−vis spectroscopy and confocal laser scannin...

Schizophyllan (SPG) is a natural β-(1→3)-D-glucan existing as a triple helix in water and as a single chain in dimethylsulfoxide (DMSO), respectively. As we already reported, when a homo-phosphodiester polynucleotide [for example, poly(dA) or poly(C)] is added to the SPG/DMSO solution and subsequently DMSO is exchanged for water, SPG forms a complex with the polynucleotide. One of the potential applications of this novel complex is an antisense-oligonucleotide (AS ODN) carrier. The present paper describes a modification technique which enables us to introduce transferrin to the reducing end of SPG (Tf-SPG). We made a complex from Tf-SPG and AS ODN and carried out an in vitro antisense assay. We found that Tf-SPG dramatically enhances the antisense effect. Their superiority can be ascribed to enhancement of endocytosis due to the attached transferrin. One of the peculiar features of our system is that the complex (i.e., carrier + AS ODN) is charged negatively in total, because SPG itself is a neutral polysaccharide. This feature is different from the conventional systems such as cationic liposomes and polycations. The present work has thus clarified that SPG can act as a new potential candidate for AS ODN carriers. [DOI: 10.1380/ejssnt.2005.195]

Two kinds of polymeric nanoarchitectures, i.e., one-dimensional polymer composites and two-dimensional sheet-like structures, can be created using a semiartificial helical polysaccharide with one-d...

The water solubility of curdlan was enhanced by partial sulfation at O-6. Circular dichroism measurements suggest that the sulfated curdlan with the degree of substitution (DS) from 0 to 8.7 mol % forms macromolecular complexes with polycytidylic acid (poly(C)). Although the thermal stability of the complexes decreased with increase in DS, this could be overlapped by addition of NaCl in the concentration above that of serum. The results clearly indicate that the drawback arising from the electrostatic repulsion between the anionic charges can be partially compensated by the presence of salt. Furthermore, the polynucleotide chain complexed with the sulfated curdlan was protected from the enzymatic hydrolysis, corroborating the assumption that the sulfated curdlan has an ability to bind poly(C).

By mixing boronic acid-modified poly(acrylic acid) (pAA-BA) and β-1,3-glucan Schizophyllan (SPG) in water at pH 9.9, hydrogel was readily formed with the aid of the sugar and boronic acid interacti...

Developing new strategies for controlling polymer conformations through precise molecular recognition can potentially generate a machine-like motion that is dependent on molecular information-an important process for the preparation of new intelligent nanomaterials (e.g., polymer-based nanomachines) in the field bordering between polymer chemistry and conventional supramolecular sciences. Herein, we propose a strategy to endow a helical polymer chain with dynamic spring-like (contraction/expansion) motion through the one-dimensional self-assembly (aggregation/disaggregation) of peripheral amphiphilic molecules. In this developing system, we employed a semi-artificial helical polysaccharide presenting peripheral amphiphilic chlorophyll units as a power device that undergoes contractive motion in aqueous media, driven by strong π-π interactions of its chlorophyll units or by cooperative molecular recognition of bipyridyl-type ligands through pairs of chlorophyll units, thereby converting molecular information into the regulated motion of a spring. In addition, this system also undergoes expansive motion through coordination of pyridine. We anticipate that this strategy will be applicable (when combined with the established wrapping chemistry of the helical polysaccharide) to the development of, for example, drug carriers (e.g., nano-syringes), actuators (stimuli-responsive films), and directional transporters (nano-railways), thereby extending the frontiers of supramolecular science.

One of the fundamental problems in supramolecular chemistry, as well as in material sciences, is how to control the self-assembly of polymers on the nanometer scale and how to spontaneously organize them towards the macroscopic scale. To overcome this problem, inspired by the self-assembly systems in nature, which feature the dynamically controlled self-assembly of biopolymers, we have previously proposed a self-assembly system that uses a dynamic liquid/liquid interface with dimensions in the micrometer regime, thereby allowing polymers to self-assemble under precisely controlled nonequilibrium conditions. Herein, we further extend this system to the creation of hierarchical self-assembled architectures of polysaccharides. A natural polysaccharide, β-1,3-glucan (SPG), and water were injected into opposite "legs" of microfluidic devices that had a Y-shape junction, so that two solvents would gradually mix in the down stem, thereby causing SPG to spontaneously self-assemble along the flow in a head-to-tail fashion, mainly through hydrophobic interactions. In the initial stage, several SPG nanofibers would self-assemble at the Y-junction owing to the shearing force, thereby creating oligomers with a three-way junction point. This unique structure, which could not be created through conventional mixing procedures, has a divergent self-assembly capability. The dynamic flow allows the oligomers to interact continuously with SPG nanofibers that are fed into the Y-junction, thus amplifying the nanostructure along the flow to form SPG networks. Consequently, we were able to create stable, centimeter-length macroscopic polysaccharide strands under the selected flow conditions, which implies that SPG nanofibers were assembled hierarchically in a supramolecular fashion in the dynamic flow. Microscopic observations, including SEM and AFM analysis, revealed the existence of clear hierarchical structures inside the obtained strand. The network structures self-assembled to form sub-micrometer-sized fibers. The long fibers further entangled with each other to give stable micrometer-sized fibers, which finally assembled to form the macroscopic strands, in which the final stabilities in the macroscopic regime were governed by that of the network structures in the nanometer regime. Thus, we have exploited this new supramolecular system to create hierarchical polymeric architectures under precisely controlled flow conditions, by combining the conventional supramolecular strategy with microfluidic science.

Creation of higher-ordered polymeric architectures composed of alternative assemblies of single-walled carbon nanotubes (SWNTs) and fibrous porphyrin J-aggregates can be easily achieved utilizing the cationic semi-artificial polysaccharide which can act not only as a tubular host for SWNTs but also as a one-dimensional template for porphyrin molecules. This new class of hierarchical polymer assembly is formed, for the first time, by the mutual template effect of two components, i.e., the cationic SWNT complexes and the anionic porphyrin supramolecular nanofibers. In the present system, the self-assembling behaviors of the SWNT complexes as well as the final properties of the SWNT nanoarchitectures are strongly affected by the packing mode of porphyrin molecules on the cationic semi-artificial polysaccharide. Furthermore, we have confirmed that the light energy captured by the porphyrin J-aggregates is effectively transferred to SWNTs.

We have demonstrated that giant polymer micelles with a uniform diameter (ca. 200 nm) can be fabricated by "supramolecular wrapping" of poly(styrene) (PS) with the beta-1,3-glucan polysaccharide, with the beta-1,3-glucan fastening the PS chains together in a noncovalent fashion to facilitate the formation of a supramolecular polymer network on the O/W emulsion surface. Various spectroscopic and microscopic investigations have revealed that the inner cores of the micelles are comprised of a hydrophobic PS network, whereas the surfaces consist of a hydrophilic beta-1,3-glucan layer. Accordingly, functional guest molecules can easily be encapsulated inside the cavity through hydrophobic interactions. The encapsulated molecules can simply be released from the micelle cores by peeling off the beta-1,3-glucan shell in a supramolecular manner. As functional groups can be introduced into the glucose side-chain unit in a straightforward manner by chemical modification, the micellar surface can acquire further functions useful for molecular recognition. These results show that the micelles obtained could have applications as novel soft nanoparticles, which would be indispensable not only for nanotechnologies, but also for biotechnologies aimed at gene or drug delivery systems.

β-1,3-Glucans act as unique natural nanotubes, the featuresof which are greatly different from other natural or synthetic helical polymers. The origin mostly stemsfrom their strong helix-forming nature and reversible interconversion between single-strand random coiland triple-strand helix. During this interconversion process, they can accept functional polymers, molecularassemblies and nanoparticles in an induced-fit manner to create water-soluble one-dimensional nanocomposites,where individual conjugated polymers or molecular assemblies can be incorporated into the one-dimensionalhollow constructed by the helical superstructure of β-1,3-glucans.The advantageous point of the β-1,3-glucan hosting system is thatthe selective modification of β-1,3-glucans leads to the creationof various functional one-dimensional nanocomposites in a supramolecular manner, being applicable towardfundamental nanomaterials such as sensors or circuits. Furthermore, the composites with functional surfacescan act as one-dimensional building blocks toward further hierarchical self-assemblies, leading to the creationof two- or three-dimensional nanoarchitectures.

We synthesized a semiartificial beta-1,3-glucan, curdlan with dialkylaniline groups (CUR-DA), that bears chromophoric aromatic groups at its peripheral positions. Spectroscopic studies as well as microscopic observations indicate that CUR-DA adopts a triple-stranded helical structure in water- or methanol-rich solutions of dimethyl sulfoxide (DMSO). This triple-stranded helical structure exhibits high thermal stability and resistance to base, attributes that are similar to those of the triple-stranded helical structure of native beta-1,3-glucans such as schizophyllan. Moreover, we found that the stability of the triple-stranded helical structure can be easily modulated by solvent composition and metal-ion (Zn2+) binding. As beta-1,3-glucan polysaccharides are known to serve as "polymeric" hosts, including certain DNA molecules, carbon nanotubes, and conjugated polymers, and complexation occurs only with the single-stranded structure, this information is very useful for the creation of these attractive polymeric composites, the controlled release of DNA, and so on.

Schizophyllan interacts with various 1,4-diphenylbutadiyne derivatives to induce their chirally-twisted packing. A series of referential experiments using other polysaccharides (amylose, pullulan, dextran, etc.) and a carbohydrate-appended detergent (dodecyl-beta-d-glucopyranoside) indicates that these 1,4-diphenylbutadiyne derivatives are accommodated within a tubular cavity constructed by a helical superstructure of schizophyllan. In these 1,4-diphenylbutadiyne derivatives, 1,4-bis(p-propionamidophenyl)butadiyne can be easily polymerized through UV-irradiation, in which schizophyllan acts as a one-dimensional mold to produce the corresponding poly(diacetylene)s with fibrous morphologies. Detailed investigations on this unique approach to prepare the nanofibers revealed that it includes two individual processes, that is, 1) UV-mediated polymerization of encapsulated 1,4-bis(p-propionamidophenyl)butadiyne to produce immature nanofibers and 2) their reorganization through hydrophobic interfiber interactions into ordered nanofibers. The other 1,4-diphenylbutadiyne derivatives could not be polymerized through UV-irradiation, indicating that the p-propionamido-functionalities play substantial roles for a suitable packing of the monomer for the polymerization. The other 1,4-diphenylbutadiyne derivatives, however, can be also polymerized through gamma-ray irradiation in the presence of schizophyllan to give the corresponding poly(diacetylene)-nanofibers, emphasizing the wide applicability of the schizophyllan-based strategy for polymerization of various 1,4-diphenylbutadiyne derivatives.

We have demonstrated that the creation of novel silica nanofibers with a uniform diameter is possible by utilizing beta-1,3-glucan polysaccharide as a one-dimensional host for monoalkoxysilane; the finding establishes that beta-1,3-glucan can act not only as a novel one-dimensional host for metal alkoxide polycondensation but also as an interface between inorganic nanofibers and functional organic molecules.

Beta-1,3-glucan polysaccharides have triple-stranded helical structures whose sense and pitch are comparable to those of polynucleotides. We recently revealed that the beta-1,3-glucans could interact with certain polynucleotides to form triple-stranded and helical macromolecular complexes consisting of two polysaccharide-strands and one polynucleotide-strand. This unique property of the beta-1,3-glucans has made it possible to utilize these polysaccharides as potential carriers for various functional polynucleotides. In particular, cell-uptake efficiency of the resultant polysaccharide/polynucleotide complexes was remarkably enhanced when functional groups recognized in a biological system were introduced as pendent groups. The beta-1,3-glucans can also interact with various one-dimensional architectures, such as single-walled carbon nanotubes, to produce unique nanocomposites, in which the single-walled carbon nanotubes are entrapped within the helical superstructure of beta-1,3-glucans. Various conductive polymers and gold nanoparticles are also entrapped within the helical superstructure in a similar manner. In addition, diacetylene monomers entrapped within the helical superstructure can be photo-polymerized to afford the corresponding poly(diacetylene)-nanofibers with a uniform diameter. These findings indicate that the beta-1,3-glucans are very attractive and useful materials not only in biotechnology but also in nanotechnology. These unique properties of the beta-1,3-glucans undoubtedly originate from their inherent, very strong helix-forming character which has never been observed for other polysaccharides.

We have found that single-chain schizophyllan and curdlan (s-SPG and s-curdlan, respectively) can dissolve as-grown and cut single-walled carbon nanotubes (ag-SWNTs and c-SWNTs, respectively) in aqueous solution. The vis-NIR spectra of the composites suggest that c-SWNTs are dissolved as a bundle, whereas ag-SWNTs exist as one or only a few pieces in the tubular hollow constructed by the helical structure inherent to these beta-1,3-glucans. EDX and CLSM measurements and TEM observation established that the distribution map of these polysaccharides overlaps well with the image of SWNTs, indicating that these two components form a composite. Very interestingly, when c-SWNTs were dissolved with the aid of s-SPG or s-curdlan in water, a clear periodical structure with inclined stripes, as detected by AFM, appeared on the fibrous composite surface. Because this periodical structure has never been recognized for the composites with other water-soluble polymers, one can regard that s-SPG or s-curdlan wraps c-SWNTs constructing a helically twined structure. High-resolution TEM observation of an ag-SWNTs/s-SPG composite gave a clearer image in that two s-SPG chains twine one ag-SWNT and the helical motif is right-handed. When this sample was subjected to the AFM measurement, the composite showed the 2-3 nm height. This height implies that one piece of ag-SWNT is included in the s-SPGs helical structure. As a summary, it has been established that beta-1,3-glucans such as s-SPG and s-curdlan not only dissolve SWNTs but also create a novel superstructure on the surface.

We here demonstrate the creation of novel poly(aniline) (PANI) nanofiber structures by a polymer wrapping method using schizophyllan (SPG). Mannose-modified SPG can also wrap PANIs to give nanofibers having a lectin affinity. This interaction is applicable to designing novel PANI/protein composites. The results establish that SPG can act as a novel "host" to assemble PANIs into one-dimensional superstructures. [reaction: see text]

Schizophyllans carrying beta-lactoside and alpha-mannoside appendages were prepared from native schizophyllan through NaIO4 oxidation followed by reductive amination using aminoethyl-beta-lactoside and alpha-mannoside, respectively. The resulting schizophyllans form stable macromolecular complexes with polynucleotides, such as poly(C) and poly(dA). Specific affinity between these macromolecular complexes and saccharide-binding proteins was demonstrated by surface plasmon resonance and agarose gel staining assays. beta-lactoside-appended schizophyllan enhanced an antisense activity in hepatocytes which express lactoside-binding proteins on their cell surfaces.

Schizophyllan (SPG), a beta-1,3-glucan polysaccharide which is known to form macromolecular complexes with certain polynucleotides, was modified by a reductive amination method with alpha-amino acids (Arg, Lys, and Ser). The thermal stability of the complexes as estimated by T(m) was enhanced in SPG-Arg and SPG-Lys conjugates which have pI values higher than the pH of the medium (8.0). The T(m) shift increased with the increase in the percentage of alpha-amino acid introduced and the highest T(m) values attained were 64 degrees C for SPG-Arg conjugate and 62 degrees C for SPG-Lys conjugate, which are higher by 13 and 11 degrees C, respectively, than those of the unmodified SPG+poly(C) complex. In the SPG-Ser conjugate with a pI lower than the medium pH (8.0), the T(m) values decreased with an increase in the percentage of Ser. Formation of the macromolecular complex was no longer detected above 13.2% Ser. The findings indicate that the T(m) values are easily controllable by the type and percentage of the introduced alpha-amino acids. We believe, therefore, that the present conjugates, consisting of naturally originated SPG and alpha-amino acids, provide an important lead for developing nontoxic artificial vectors and to control the affinity with polynucleotides in response to medium pH and temperature.

We have revealed unique template effects of a semiartificial polysaccharide on the self-assembly of anionic cyanine dyes. The inner space of the polysaccharide acts not only as a nanotemplate for t...

We have developed a novel approach to the preparation of a circularly polarized luminescence material from a natural polysaccharide host and an achrial polythiophene guest.

A conformation-sensitive optical method for monitoring the random coil–helix transition of polysaccharides has been developed by using a water-soluble polythiophene.

We have exploited novel supramolecular wrapping techniques by helix-forming polysaccharides, β-1,3-glucans, which have strong tendency to form regular helical structures on versatile nanomaterials in an induced-fit manner. This approach is totally different from that using the conventional interpolymer interactions seen in both natural and synthetic polymeric architectures, and therefore has potential to create novel polymeric architectures with diverse and unexpected functionalities. The wrapping by β-1,3-glucans enforces the entrapped guest polymer to adopt helical or twisted conformations through the convergent interpolymer interactions. On the contrary, the wrapping by chemically modified semi-artificial β-1,3-glucans can bestow the divergent self-assembling abilities on the entrapped guest polymer to create hierarchical polymeric architectures, where the polymer/β-1,3-glucan composite acts as a huge one-dimensional building block. Based on the established wrapping strategy, we have further extended the wrapping techniques toward the creation of three-dimensional polymeric architectures, in which the polymer/β-1,3-glucan composite behaves as a sort of amphiphilic block copolymers. The present wrapping system would open several paths to accelerate the development of the polymeric supramolecular assembly systems, giving the strong stimuli to the frontier of polysaccharide-based functional chemistry.

We have developed a novel approach to construct one-dimensional chiral assemblies from an achiral, dipolar dye molecule in the hydrophobic core of schizophyllan, a natural polysaccharide: they resulted in unusually red-shifted absorption maxima, in some cases appearing at the NIR region.

Aggregates obtained from saccharide-containing dendrons were immobilized by in situ cross-link with 1,3-phenylene diisocyanate. Characterizations of the resultant oligomers by dynamic light scattering and MALDI-TOF Mass have established that the higher generation dendrons which tend to aggregate into a spherical structure result in a dendritic polymer whereas the lower generation dendrons which tend to aggregate into a disordered large particle cannot result in such a dendrimer-shaped oligomer.

We previously found that polysaccharide "schizophyllan (SPG)" can entrap as-grown and cut single-walled carbon nanotubes (as-SWNTs and c-SWNTs, respectively): we here reported that the c-SWNT-s-SPG (single stranded SPG) composites thus obtained can be aligned regularly using the covalent bond formation between boric acid or boronic acid derivatives and the 4,6-dihydroxyl group of the glucose side-chain unit.

Beta-1,3-glucans having carbohydrate-appendages (alpha-D-mannoside, N-acetyl-beta-D-glucosaminide and beta-lactoside) at the C6-position of every repeating unit can be readily prepared from curdlan (a linear beta-1,3-glucan) through regioselective bromination/azidation to afford 6-azido-6-deoxycurdlan followed by chemo-selective Cu(i)-catalyzed [3 + 2]-cycloaddition with various carbohydrate modules having a terminal alkyne. The resultant carbohydrate-appended curdlans can interact with polycytosine to form stable macromolecular complexes consistent with two polysaccharide strands and one polycytosine strand. Furthermore, these macromolecular complexes show strong and specific affinity toward carbohydrate-binding proteins (lectins). Therefore, one can utilize these carbohydrate-appended curdlans as a new family of glycoclusters.