Nanoarchitectonics beyond Self-Assembly: Challenges to Create Bio-Like Hierarchic Organization

Incorporation of non-equilibrium actions in the sequence of self-assembly processes would be an effective means to establish bio-like high functionality hierarchical assemblies. As a novel methodology beyond self-assembly, nanoarchitectonics, which has as its aim the fabrication of functional materials systems from nanoscopic units through the methodological fusion of nanotechnology with other scientific disciplines including organic synthesis, supramolecular chemistry, microfabrication, and bio-process, has been applied to this strategy. The application of non-equilibrium factors to conventional self-assembly processes is discussed on the basis of examples of directed assembly, Langmuir-Blodgett assembly, and layer-by-layer assembly. In particular, examples of the fabrication of hierarchical functional structures using bio-active components such as proteins or by the combination of bio-components and two-dimensional nanomaterials, are described. Methodologies described in this review article highlight possible approaches using the nanoarchitectonics concept beyond self-assembly for creation of bio-like higher functionalities and hierarchical structural organization.

Preparation of Long-Term Antibacterial SiO2-Cinnamaldehyde Microcapsule via Sol-Gel Approach as a Functional Additive for PBAT Film

The mesoporous silica wall materials can achieve controlled load and sustained-release of active agents. An antimicrobial nanoscale silica microcapsule containing cinnamaldehyde (CA) was prepared by the sol-gel method and applied in poly (butyleneadipate-co-terephthalate) (PBAT) film. The surface morphology, physical and chemical properties, and antibacterial properties of microcapsules and films were studied. The effects of different temperatures and humidities on the release behavior of microcapsules were also evaluated. Results showed that CA was successfully encapsulated in silica microcapsule which had a diameter of 450–700 nm. The antibacterial CA agent had a long-lasting release time under lower temperature and relative humidity (RH) environment. At low temperature (4 °C), the microcapsules released CA 32.35% in the first 18 h, and then slowly released to 56.08% in 216 h; however, the microcapsules released more than 70% in 18 h at 40 °C. At low humidity (50%RH), the release rates of microcapsules at the 18th h and 9th d were 43.04% and 78.01%, respectively, while it reached to equilibrium state at 72 h under 90% RH. The sustained release process of CA in SiO2-CA microcapsules follows a first-order kinetic model. Physicochemical properties of PBAT films loaded with different amounts of microcapsules were also characterized. Results showed that the tensile strength and water vapor transmission rate (WVTR) of the composite film containing 2.5% microcapsules were increased by 26.98% and 14.61%, respectively, compared to the raw film, while the light transmittance was slightly reduced. The crystallinity of the film was improved and can be kept stable up to 384.1 °C. Furthermore, microcapsules and composite film both exhibited distinctive antibacterial effect on Escherichia coli and Listeria monocytogenes. Therefore, SiO2-CA microcapsules and composite films could be a promising material for the active packaging.

Don't Forget Langmuir-Blodgett Films 2020: Interfacial Nanoarchitectonics with Molecules, Materials, and Living Objects

Designing interfacial structures with nanoscale (or molecular) components is one of the important tasks in the nanoarchitectonics concept. In particular, the Langmuir-Blodgett (LB) method can become a promising and powerful strategy in interfacial nanoarchitectonics. From this viewpoint, the status of LB films in 2020 will be discussed in this feature article. After one section on the basics of interfacial nanoarchitectonics with the LB technique, various recent research examples of LB films are introduced according to classifications of (i) growing research, (ii) emerging research, and (iii) future research. In recent LB research, various materials other than traditional lipids and typical amphiphiles can be used as film components of the LB techniques. Two-dimensional materials, supramolecular structures such as metal organic frameworks, and biomaterials such as DNA origami pieces are capable of working as functional components in the LB assemblies. Possible working areas of the LB methods would cover emerging demands, including energy, environmental, and biomedical applications with a wide range of functional materials. In addition, forefront research such as molecular manipulation and cell fate control is conducted in LB-related interfacial science. The LB technique is a traditional and well-develop methodology for molecular films with a ca. 100 year history. However, there is plenty of room at the interfaces, as shown in LB research examples described in this feature article. It is hoped that the continuous development of the science and technology of the LB method make this technique an unforgettable methodology.

Layer-by-Layer Assembly: Recent Progress from Layered Assemblies to Layered Nanoarchitectonics

As an emerging concept for the development of new materials with nanoscale features, nanoarchitectonics has received significant recent attention. Among the various approaches that have been developed in this area, the fixed-direction construction of functional materials, such as layered fabrication, offers a helpful starting point to demonstrate the huge potential of nanoarchitectonics. In particular, the combination of nanoarchitectonics with layer-by-layer (LbL) assembly and a large degree of freedom in component availability and technical applicability would offer significant benefits to the fabrication of functional materials. In this Minireview, recent progress in LbL assembly is briefly summarized. After introducing the basics of LbL assembly, recent advances in LbL research are discussed, categorized according to physical, chemical, and biological innovations, along with the fabrication of hierarchical structures. Examples of LbL assemblies with graphene oxide are also described to demonstrate the broad applicability of LbL assembly, even with a fixed material.

Developing regulatory property of gelatin-tannic acid multilayer films for coating-based nitric oxide gas delivery system

To utilize potentials of nitric oxide (NO) gas in anti-bacterial, anticancer, wound healing applications, numerous studies have been conducted to develop a NO delivery system in the past few decades. Even though a coating method and film types are essential to apply in biomedical device coating from previous NO delivery systems, release control from the coating system is still challenging. In this study, we introduced a multilayered polymeric coating system to overcome the uncontrollable NO release kinetics of film systems. We used biocompatible gelatin and tannic acid to construct a rough, porous structured film based on the layer-by-layer self-assembly method. The multilayered polymeric structure facilitated the controlled amount of NO release from (Gel/TA)n film and showed burst release in early period owing to their large surface area from the rough, porous structure. We synthesized the proton-responsive NO donor, N-diazeniumdiolate (NONOates), into the (Gel/TA)n film through a chemical reaction under high pressure NO gas. NO release profile was analyzed by a real-time NO analysis machine (NOA 280i). Then, the NO-releasing (Gel/TA)n film was tested its toxicity against human dermal fibroblast cells and bactericidal effects against Staphylococcus aureus.

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.

Review of advanced sensor devices employing nanoarchitectonics concepts

Many recent advances in sensor technology have been possible due to nanotechnological advancements together with contributions from other research fields. Such interdisciplinary collaborations fit well with the emerging concept of nanoarchitectonics, which is a novel conceptual methodology to engineer functional materials and systems from nanoscale units through the fusion of nanotechnology with other research fields, including organic chemistry, supramolecular chemistry, materials science and biology. In this review article, we discuss recent advancements in sensor devices and sensor materials that take advantage of advanced nanoarchitectonics concepts for improved performance. In the first part, recent progress on sensor systems are roughly classified according to the sensor targets, such as chemical substances, physical conditions, and biological phenomena. In the following sections, advancements in various nanoarchitectonic motifs, including nanoporous structures, ultrathin films, and interfacial effects for improved sensor function are discussed to realize the importance of nanoarchitectonic structures. Many of these examples show that advancements in sensor technology are no longer limited by progress in microfabrication and nanofabrication of device structures - opening a new avenue for highly engineered, high performing sensor systems through the application of nanoarchitectonics concepts.

Nanoarchitectonic-Based Material Platforms for Environmental and Bioprocessing Applications

The challenges of pollution, environmental science, and energy consumption have become global issues of broad societal importance. In order to address these challenges, novel functional systems and advanced materials are needed to achieve high efficiency, low emission, and environmentally friendly performance. A promising approach involves nanostructure-level controls of functional material design through a novel concept, nanoarchitectonics. In this account article, we summarize nanoarchitectonic approaches to create nanoscale platform structures that are potentially useful for environmentally green and bioprocessing applications. The introduced platforms are roughly classified into (i) membrane platforms and (ii) nanostructured platforms. The examples are discussed together with the relevant chemical processes, environmental sensing, bio-related interaction analyses, materials for environmental remediation, non-precious metal catalysts, and facile separation for biomedical uses.

Materials Nanoarchitectonics for Mechanical Tools in Chemical and Biological Sensing

In this Focus Review, nanoarchitectonic approaches for mechanical-action-based chemical and biological sensors are briefly discussed. In particular, recent examples of piezoelectric devices, such as quartz crystal microbalances (QCM and QCM-D) and a membrane-type surface stress sensor (MSS), are introduced. Sensors need well-designed nanostructured sensing materials for the sensitive and selective detection of specific targets. Nanoarchitectonic approaches for sensing materials, such as mesoporous materials, 2D materials, fullerene assemblies, supported lipid bilayers, and layer-by-layer assemblies, are highlighted. Based on these sensing approaches, examples of bioanalytical applications are presented for toxic gas detection, cell membrane interactions, label-free biomolecular assays, anticancer drug evaluation, complement activation-related multiprotein membrane attack complexes, and daily biodiagnosis, which are partially supported by data analysis, such as machine learning and principal component analysis.

Calcinable Polymer Membrane with Revivability for Efficient Oily-Water Remediation

Fouling of polymeric membranes remains a major challenge for long-term operation of oily-water remediation. The common reclamation methods to recycle fouled membranes have the issues of either incomplete degradation of organic pollutants or damage to filter membranes. Here, a calcinable polymer membrane with effective reclamation after fouling is reported, which shows full recovery of the original oil/water separation efficiency. The membrane is made of polysulfonamide/polyacrylonitrile fibers by emulsion electrospinning, followed by hydrothermal decoration of TiO₂ nanoparticles. The bonding structured fibrous membrane displays outstanding thermal stability in air (400 °C), strong acid/alkali resistance (at the pH range from 1 to 13), and robust tensile strength. As a result, the chemically fouled polymeric membrane can be easily reclaimed without decreasing in separation performance and mechanical properties by annealing treatment. As a proof-of-concept, the as-prepared membrane is integrated into a wastewater separation tank, which achieves a high water flux over 3000 L m^-2 h^-1 and oil rejection efficiency of 99.6% for various oil-in-water emulsions. The presented strategy on membrane fabrication is believed to be an effective remedy for membrane fouling, and should apply in a wider field of filtration industry.