Self-assembly as a key player for materials nanoarchitectonics

The development of science and technology of advanced materials using nanoscale units can be conducted by a novel concept involving combination of nanotechnology methodology with various research disciplines, especially supramolecular chemistry. The novel concept is called 'nanoarchitectonics' where self-assembly processes are crucial in many cases involving a wide range of component materials. This review of self-assembly processes re-examines recent progress in materials nanoarchitectonics. It is composed of three main sections: (1) the first short section describes typical examples of self-assembly research to outline the matters discussed in this review; (2) the second section summarizes self-assemblies at interfaces from general viewpoints; and (3) the final section is focused on self-assembly processes at interfaces. The examples presented demonstrate the strikingly wide range of possibilities and future potential of self-assembly processes and their important contribution to materials nanoarchitectonics. The research examples described in this review cover variously structured objects including molecular machines, molecular receptors, molecular pliers, molecular rotors, nanoparticles, nanosheets, nanotubes, nanowires, nanoflakes, nanocubes, nanodisks, nanoring, block copolymers, hyperbranched polymers, supramolecular polymers, supramolecular gels, liquid crystals, Langmuir monolayers, Langmuir-Blodgett films, self-assembled monolayers, thin films, layer-by-layer structures, breath figure motif structures, two-dimensional molecular patterns, fullerene crystals, metal-organic frameworks, coordination polymers, coordination capsules, porous carbon spheres, mesoporous materials, polynuclear catalysts, DNA origamis, transmembrane channels, peptide conjugates, and vesicles, as well as functional materials for sensing, surface-enhanced Raman spectroscopy, photovoltaics, charge transport, excitation energy transfer, light-harvesting, photocatalysts, field effect transistors, logic gates, organic semiconductors, thin-film-based devices, drug delivery, cell culture, supramolecular differentiation, molecular recognition, molecular tuning, and hand-operating (hand-operated) nanotechnology.

Self-assembly patterning of ultrafine zirconia nanocrystal films fabricated on chemically patterned templates

Ultra-thin zirconia (ZrO₂) nanocrystal films were fabricated by using a controlled dip-coating process. ZrO₂ nanocrystals possess a cubic crystalline phase and large surface-to-volume area. The film composite with only several layers of nanocrystals were obtained by controlling the withdrawal speed and mass concentration of the colloidal solution. The optical properties of ZrO₂ nanocrystal films were accessed by UV-vis spectroscopy, which indicated the dense and uniform structure of the nanocrystal films. The high reflection index suggested that the films could be used in the reflection coating industry. Furthermore, a micro-pattern of self-assembled monolayers of silane molecular was used as a chemical mold for selective deposition of ZrO₂ nanocrystals. As a result, a self-assembly patterning of ZrO₂ nanocrystals with a neat edge was fabricated on silicon substrate. The low-cost fabricating method is compatible with conventional very-large-scale integration processes and can be extended to other kinds of nanocrystals.

Unique supramolecular assembly through Langmuir - Blodgett (LB) technique

The Langmuir-Blodgett (LB) technique is a way of making supra-molecular assembly in ultrathin films with a controlled layered structure and crystal parameter, which have many envisioned technological applications for optical and molecular electronic devices as well as signal processing and transformation. Probably LB technique is the best method to manipulate materials at molecular level and provides a scope to realize the molecular electronics in reality. In this review article, we have discussed about the general introduction of LB technique and recent development on LB and related system including (i) LB methodology, (ii) characterizations of LB films, (iii) LB films and molecular electronics, (iv) historical review of LB films, (v) research and applications including fundamental research and application towards devices.

Nanoarchitectonics from Molecular Units to Living-Creature-Like Motifs

Important points for the fabrication of functional materials are the creation of nanoscale/molecular-scale units and architecting them into functional materials and systems. Recently, a new conceptual paradigm, nanoarchitectonics, has been proposed to combine nanotechnology and other methodologies including supramolecular chemistry, self-assembly and self-organization to satisfy major features of nanoscience and promote the creation of functional materials and systems. In this account article, our recent research results in materials development based on the nanoarchitectonics concept are summarized in two stories, (i) nanoarchitectonics from fullerenes as the simplest nano-units and (ii) dimension-dependent nanoarchitectonics from various structural units. The former demonstrates creativity of the nanoarchitectonics concept only with simple construction stuffs on materials fabrications, and a wide range of material applicability for the nanoarchitectonics strategy is realized in the latter ones.

Surface Modification of PDMS and Plastics with Zwitterionic Polymers

Surface modification of PDMS, polycarbonate, and acrylic resin was examined using various methacryl polymers bearing sulfobetaine, phosphoryl choline, and oligoethylene glycol units. We have found that zwitterionic polymers are adsorbed on the PDMS surface treated with plasma. The surface of PDMS is stable to keep high hydrophilicity after a month of the modification. On the other hand, one of sulfobetaine polymers showed distinguished adsorption behavior in the case of polycarbonate surface treated with plasma. Suppression effect for nonspecific adsorption of BSA was evaluated using polycarbonate and acrylic resin modified with the polymers. The modified surfaces showed suppression effect for nonspecific adsorption of BSA compared with the surface only treated with plasma.

Solid surface vs. liquid surface: nanoarchitectonics, molecular machines, and DNA origami

Comparisons of science and technology between these solid and liquid surfaces would be a good navigation for current-to-future developments.