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

Surface Ammonium Ions Assisted Decoration of Monodisperse Cobalt Nanoparticles on Molybdenum Oxide Films as Efficient Electrocatalysts for Hydrogen Evolution Reaction

The high expense associated with electrocatalysts poses a challenge to the advancement of a hydrogen-based energy economy. The utilization of nonprecious metal-based electrocatalysts that are easily prepared and cost-effective is imperative for the future sustainability of a hydrogen society. The semiconductive MoO3-x has been identified as a promising nonprecious electrocatalyst for the hydrogen evolution reaction (HER). Nevertheless, enhancing its relatively low electrocatalytic activity toward HER remains a top priority. This study illustrates the manipulation of surface ammonium ions (NH4+) to produce uniform and distinct cobalt nanoparticles (Co NPs) on active MoO3-x supports, resulting in a more effective heterostructured composite electrocatalyst for HER. The presence of NH4+ ions in the MoO3-x film was extensively examined using infrared spectroscopy, X-ray photoelectron spectroscopy, and UV-visible colorimetric techniques. Additionally, the firmly attached NH4+ ions were employed as binding sites to precipitate Co-containing complex ions. Due to the monolayer-like adsorption of NH4+ ions, only a small quantity of Co precipitate was formed, which was subsequently electrochemically transformed into Co atoms that diffused and created well-separated uniform metallic Co nanoparticles (with an average size of less than 10 nm) on the MoO3-x film. The resulting heterostructure displays a 4.5-fold increase in current density for HER compared to the MoO3-x electrocatalyst through electrochemical assessments. The enhanced catalytic activity was ascribed to the optimized adsorption/desorption of the species involved in water reduction at the heterointerfaces and improved charge transfer rates. These nanoheterostructures hold great promise for a variety of applications in heterogeneous electrocatalysis, while the novel approach could potentially direct the creation of more heterostructures.

Temperature-Induced Nanoarchitectonics of Monolayer Self-Assembly of Heterocoronene-Based Discotic Liquid Crystals

Enhancing molecular self-assembly at the monolayer level offers significant potential for various applications. For monolayers made of π-conjugated discotic liquid crystal (DLC) molecule nanowires, achieving precise separation and alignment of these nanowires has been a long-standing challenge. This research explores an approach using the manipulation of subphase temperature and surface pressure within a Langmuir trough to control molecular nanowire separation. We observe notable temperature-dependent behavior: as the temperature increases from 5 to 30 °C, the monolayer collapse pressure rises steadily. In contrast, temperatures from 35 to 50 °C exhibit an initial small plateau with a nonzero slope that becomes more distinct with rising temperature. Our study of Langmuir-Blodgett (LB) films provides crucial insights into the monolayer's structure. At lower temperatures, the LB films show coalesced molecular nanowires, whereas at higher temperatures, the DLC nanowires separate and form an interconnected network. Remarkably, upon compression, this network transforms into a compact, highly uniform monolayer. To explain these temperature-dependent behaviors, we examine the area relaxation curves, which indicate a two-step molecular loss mechanism involving desorption and monolayer collapse due to the nucleation and growth of critical nuclei. This extensive study offers valuable insights into the dynamic interaction of the temperature, surface pressure, and molecular assembly, enhancing our understanding of the fundamental processes in monolayer self-assembly.

Bio-gel nanoarchitectonics in tissue engineering

Given the creation of materials based on nanoscale science, nanotechnology must be combined with other disciplines. This role is played by the new concept of nanoarchitectonics, the process of constructing functional materials from nanocomponents. Nanoarchitectonics may be highly compatible with applications in biological systems. Conversely, it would be meaningful to consider nanoarchitectonics research oriented toward biological applications with a focus on materials systems. Perhaps, hydrogels are promising as a model medium to realize nanoarchitectonics in biofunctional materials science. In this review, we will provide an overview of some of the defined targets, especially for tissue engineering. Specifically, we will discuss (i) hydrogel bio-inks for 3D bioprinting, (ii) dynamic hydrogels as an artificial extracellular matrix (ECM), and (iii) topographical hydrogels for tissue organization. Based on these backgrounds and conceptual evolution, the construction strategies and functions of bio-gel nanoarchitectonics in medical applications and tissue engineering will be discussed.

Interface-Interactive Nanoarchitectonics: Solid and/or Liquid

The methodology of nanoarchitectonics is to construct functional materials using nanounits such as atoms, molecules, and nanoobjects, just like architecting buildings. Nanoarchitectonics pursues the ultimate concept of materials science through the integration of related fields. In this review paper, under the title of interface-interactive nanoarchitectonics, several examples of structure fabrication and function development at interfaces will be discussed, highlighting the importance of architecting materials with nanoscale considerations. Two sections provide some examples at the solid and liquid surfaces. In solid interfacial environments, molecular structures can be precisely observed and analyzed with theoretical calculations. Solid surfaces are a prime site for nanoarchitectonics at the molecular level. Nanoarchitectonics of solid surfaces has the potential to pave the way for cutting-edge functionality and science based on advanced observation and analysis. Liquid surfaces are more kinetic and dynamic than solid interfaces, and their high fluidity offers many possibilities for structure fabrications by nanoarchitectonics. The latter feature has advantages in terms of freedom of interaction and diversity of components, therefore, liquid surfaces may be more suitable environments for the development of functionalities. The final section then discusses what is needed for the future of material creation in nanoarchitectonics.

Liquid-Liquid and Liquid-Solid Interfacial Nanoarchitectonics

Nanoscale science is becoming increasingly important and prominent, and further development will necessitate integration with other material chemistries. In other words, it involves the construction of a methodology to build up materials based on nanoscale knowledge. This is also the beginning of the concept of post-nanotechnology. This role belongs to nanoarchitectonics, which has been rapidly developing in recent years. However, the scope of application of nanoarchitectonics is wide, and it is somewhat difficult to compile everything. Therefore, this review article will introduce the concepts of liquid and interface, which are the keywords for the organization of functional material systems in biological systems. The target interfaces are liquid-liquid interface, liquid-solid interface, and so on. Recent examples are summarized under the categories of molecular assembly, metal-organic framework and covalent organic framework, and living cell. In addition, the latest research on the liquid interfacial nanoarchitectonics of organic semiconductor film is also discussed. The final conclusive section summarizes these features and discusses the necessary components for the development of liquid interfacial nanoarchitectonics.

The effect of structural changes on the self-assembly of novel green pyridinium-carboxylate gemini surfactants in Langmuir and Langmuir-Blodgett films

Engineered molecules with tailored molecular structures have the potential to advance various disciplines by enhancing the properties of biological membranes. In this study, we investigated the fundamental interfacial behavior of newly synthesized, water insoluble, cationic pyridinium-carboxylate based gemini surfactants (GSs) using picolinic acid (PA), nicotinic acid (NA), and isonicotinic acid (INA) and their interactions with dipalmitoylphosphatidylcholine (DPPC) in Langmuir and Langmuir-Blodgett (LB) films. Two synthetic methodologies were employed: (a) connecting two alkyl pyridinecarboxylates through the nitrogen atoms with a xylenyl spacer, namely, PAGS, NAGS1, and INAGS; and (b) dimerizing two nicotinic acid molecules through ester linkages with 1,4-benzenedimethanol, and then quaternizing the pyridine nitrogens with hexadecyl chains to yield NAGS2. A combination of Brewster angle microscopy (BAM) and atomic force microscopy (AFM) imaging techniques yielded valuable insights into the morphology of the GS films and their mixtures with DPPC. Density functional theory (DFT) calculations were used to gain further information on the GSs structures and understand their assembly. The results indicate that the film of INAGS is the most hydrophobic film, and its monolayer is the least compressible. When the nitrogen atom and a carboxylate group of the headgroup are positioned closer to each other, the GS molecules tend to form aggregates instead of a continuous film which is observed for the INAGS surfactant. This observation is consistent with the DFT energy values of pair interactions, indicating that both PAGS and NAGS1 have closely packed conformations with high stabilization energy.

Molecular machines working at interfaces: physics, chemistry, evolution and nanoarchitectonics

As a post-nanotechnology concept, nanoarchitectonics combines nanotechnology with advanced materials science. Molecular machines made by assembling molecular units and their organizational bodies are also products of nanoarchitectonics. They can be regarded as the smallest functional materials. Originally, studies on molecular machines analyzed the average properties of objects dispersed in solution by spectroscopic methods. Researchers' playgrounds partially shifted to solid interfaces, because high-resolution observation of molecular machines is usually done on solid interfaces under high vacuum and cryogenic conditions. Additionally, to ensure the practical applicability of molecular machines, operation under ambient conditions is necessary. The latter conditions are met in dynamic interfacial environments such as the surface of water at room temperature. According to these backgrounds, this review summarizes the trends of molecular machines that continue to evolve under the concept of nanoarchitectonics in interfacial environments. Some recent examples of molecular machines in solution are briefly introduced first, which is followed by an overview of studies of molecular machines and similar supramolecular structures in various interfacial environments. The interfacial environments are classified into (i) solid interfaces, (ii) liquid interfaces, and (iii) various material and biological interfaces. Molecular machines are expanding their activities from the static environment of a solid interface to the more dynamic environment of a liquid interface. Molecular machines change their field of activity while maintaining their basic functions and induce the accumulation of individual molecular machines into macroscopic physical properties molecular machines through macroscopic mechanical motions can be employed to control molecular machines. Moreover, research on molecular machines is not limited to solid and liquid interfaces; interfaces with living organisms are also crucial.

Layer-by-layer designer nanoarchitectonics for physical and chemical communications in functional materials

Nanoarchitectonics, as a post-nanotechnology concept, constructs functional materials and structures using nanounits of atoms, molecules, and nanomaterials as materials. With the concept of nanoarchitectonics, asymmetric structures, and hierarchical organization, rather than mere assembly and organization of structures, can be produced, where rational physical and chemical communications will lead to the development of more advanced functional materials. Layer-by-layer assembly can be a powerful tool for this purpose, as exemplified in this feature paper. This feature article explores the possibility of constructing advanced functional systems based on recent examples of layer-by-layer assembly. We will illustrate both the development of more basic methods and more advanced nanoarchitectonics systems aiming towards practical applications. Specifically, the following sections will provide examples of (i) advancement in basics and methods, (ii) physico-chemical aspects and applications, (iii) bio-chemical aspects and applications, and (iv) bio-medical applications. It can be concluded that materials nanoarchitectonics based on layer-by-layer assembly is a useful method for assembling asymmetric structures and hierarchical organization, and is a powerful technique for developing functions through physical and chemical communication.

Confined Space Nanoarchitectonics for Dynamic Functions and Molecular Machines

Nanotechnology has advanced the techniques for elucidating phenomena at the atomic, molecular, and nano-level. As a post nanotechnology concept, nanoarchitectonics has emerged to create functional materials from unit structures. Consider the material function when nanoarchitectonics enables the design of materials whose internal structure is controlled at the nanometer level. Material function is determined by two elements. These are the functional unit that forms the core of the function and the environment (matrix) that surrounds it. This review paper discusses the nanoarchitectonics of confined space, which is a field for controlling functional materials and molecular machines. The first few sections introduce some of the various dynamic functions in confined spaces, considering molecular space, materials space, and biospace. In the latter two sections, examples of research on the behavior of molecular machines, such as molecular motors, in confined spaces are discussed. In particular, surface space and internal nanospace are taken up as typical examples of confined space. What these examples show is that not only the central functional unit, but also the surrounding spatial configuration is necessary for higher functional expression. Nanoarchitectonics will play important roles in the architecture of such a total system.

2D Materials Nanoarchitectonics for 3D Structures/Functions

It has become clear that superior material functions are derived from precisely controlled nanostructures. This has been greatly accelerated by the development of nanotechnology. The next step is to assemble materials with knowledge of their nano-level structures. This task is assigned to the post-nanotechnology concept of nanoarchitectonics. However, nanoarchitectonics, which creates intricate three-dimensional functional structures, is not always easy. Two-dimensional nanoarchitectonics based on reactions and arrangements at the surface may be an easier target to tackle. A better methodology would be to define a two-dimensional structure and then develop it into a three-dimensional structure and function. According to these backgrounds, this review paper is organized as follows. The introduction is followed by a summary of the three issues; (i) 2D to 3D dynamic structure control: liquid crystal commanded by the surface, (ii) 2D to 3D rational construction: a metal-organic framework (MOF) and a covalent organic framework (COF); (iii) 2D to 3D functional amplification: cells regulated by the surface. In addition, this review summarizes the important aspects of the ultimate three-dimensional nanoarchitectonics as a perspective. The goal of this paper is to establish an integrated concept of functional material creation by reconsidering various reported cases from the viewpoint of nanoarchitectonics, where nanoarchitectonics can be regarded as a method for everything in materials science.

Beyond traditional biosensors: Recent advances in gold nanoparticles modified electrodes for biosensing applications

Gold nanoparticles (AuNPs) have emerged as powerful tools in the construction of highly sensitive electrochemical biosensors. Their unique properties, such as the ability to serve as an effective platform for biomolecule immobilization and to facilitate electron transfer between the electrode surface and the immobilized molecules, make them a promising choice for biosensor applications. Utilizing AuNPs modified electrodes can lead to improved sensitivity and lower limits of detection compared to unmodified electrodes. This review provides a comprehensive overview of the recent advancements and applications of AuNPs-based electrochemical biosensors in the biomedical field. The synthesis methods of AuNPs, their key properties, and various strategies employed for electrode modification are discussed. Furthermore, this review highlights the remarkable applications of these nanostructure-integrated electrodes, including immunosensors, enzyme biosensors, and DNA biosensors.

Materials Nanoarchitectonics at Dynamic Interfaces: Structure Formation and Functional Manipulation

The next step in nanotechnology is to establish a methodology to assemble new functional materials based on the knowledge of nanotechnology. This task is undertaken by nanoarchitectonics. In nanoarchitectonics, we architect functional material systems from nanounits such as atoms, molecules, and nanomaterials. In terms of the hierarchy of the structure and the harmonization of the function, the material created by nanoarchitectonics has similar characteristics to the organization of the functional structure in biosystems. Looking at actual biofunctional systems, dynamic properties and interfacial environments are key. In other words, nanoarchitectonics at dynamic interfaces is important for the production of bio-like highly functional materials systems. In this review paper, nanoarchitectonics at dynamic interfaces will be discussed, looking at recent typical examples. In particular, the basic topics of "molecular manipulation, arrangement, and assembly" and "material production" will be discussed in the first two sections. Then, in the following section, "fullerene assembly: from zero-dimensional unit to advanced materials", we will discuss how various functional structures can be created from the very basic nanounit, the fullerene. The above examples demonstrate the versatile possibilities of architectonics at dynamic interfaces. In the last section, these tendencies will be summarized, and future directions will be discussed.

Graphene-Based Nanomaterials and Their Interactions with Lipid Membranes

Graphene-based nanomaterials (GNMs) have captured increasing attention in the recent advancement of materials science and nanotechnology owing to their excellent physicochemical properties. Despite having unquestionable advances, the application of GNMs in biological and medical sciences is still limited due to the lack of knowledge and precise control over their interaction with the biological milieu. The cellular membrane is the first barrier with which GNMs interact before entering a cell. Therefore, understanding how they interact with cell membranes is important from the perspective of safe use in biological and biomedical fields. In this review, we systematically summarize the recent efforts in predicting the interactions between GNMs and model cellular membranes. This review provides insights into how GNMs interact with lipid membranes and self-assemble in and around them. Both the computational simulations and experimental observations are summarized. The interactions are classified depending on the physicochemical properties (structure, chemistry, and orientation) of GNMs and various model membranes. The thermodynamic parameters, structural details, and supramolecular forces are listed to understand the interactions which would help circumvent potential risks and provide guidance for safe use in the future. At the end of this review, future prospective and emerging challenges in this research field are discussed.

Air/liquid interfacial formation process of conductive metal-organic framework nanosheets

The air/liquid interface is a superior platform to create nanosheets of materials by promoting spontaneous two-dimensional growth of components. Metal-organic frameworks (MOFs)-intrinsically porous crystals-with π-conjugated triphenylene-based ligands show high electrical conductivities. Forming nanosheets of such conductive MOFs should enable their use in electronic devices. Although highly conductive MOF nanosheets have been created at the air/liquid interface, direct control of their continuity, morphology, thickness, crystallinity, and orientation directly influencing device performance remains as an issue to be addressed. Here, we present detailed insights into the formation process of electrically conductive MOF nanosheets composed of 2,3,6,7,10,11-hexaiminotriphenylene (HITP) and Ni2+ ions (HITP-Ni-NS) at the air/liquid interface. The morphological and structural features of HITP-Ni-NS strongly depend on the standing time-the time without any external actions involved, but leaving the interface undisturbed after setting the ligand solution onto the metal-ion solution. We find that the fundamental features of HITP-Ni-NS are determined by the standing time with conductivity sensitively influenced by such pre-determined HITP-Ni-NS characteristics. These findings will lead towards the establishment of a rational strategy for creating MOF nanosheets at the air/liquid interface with desired properties, thereby accelerating their use in diverse potential applications.

Interface-mediated protein aggregation

The aggregation of proteins at interfaces has significant roles and can also lead to dysfunction of different physiological processes. The interfacial effects on the assembly and aggregation of biopolymers are not only crucial for a comprehensive understanding of protein biological functions, but also hold great potential for advancing the state-of-the-art applications of biopolymer materials. Recently, there has been remarkable progress in a collaborative context, as we strive to gain control over complex interfacial assembly structures of biopolymers. These biopolymer structures range from the nanoscale to mesoscale and even macroscale, and are attained through the rational design of interactions between biological building blocks and surfaces/interfaces. This review spotlights the recent advancements in interface-mediated assembly and properties of biopolymer materials. Initially, we introduce the solid-liquid interface (SIL)-mediated biopolymer assembly that includes the inorganic crystalline template effect and protein self-adoptive deposition through phase transition. Next, we display the advancement of biopolymer assembly instigated by the air-water interface (AWI) that acts as an energy conversion station. Lastly, we discuss succinctly the assembly of biopolymers at the liquid-liquid interface (LLI) along with their applications. It is our hope that this overview will stimulate the integration and progression of the science of interfacial assembled biopolymer materials and surfaces/interfaces.

Ionic Liquid-Induced Assembly of DNA at Air-Water Interface

DNA nanotechnology is the future of many products in the pharmaceutical and cosmetic industries. Self-assembly of this negatively charged biopolymer at surfaces and interfaces is an essential step to elaborate its field of applications. In this study, the ionic liquid (IL) monolayer-assisted self-assembly of DNA macromolecules at the air-water interface has been closely monitored by employing various quantitative techniques, namely, surface pressure-area (π-A) isotherms, surface potential, interfacial rheology, and X-ray reflectivity (XRR). The π-A isotherms reveal that the IL 1,3-didecyl 3-methyl imidazolium chloride induces DNA self-assembly at the interface, leading to a thick viscoelastic film. The interfacial rheology exhibits a notable rise in the viscoelastic modulus as the surface pressure increases. The values of storage and loss moduli measured as a function of strain frequency suggest a relaxation frequency that depends on the length of the macromolecule. The XRR measurements indicate a considerable increase in DNA layer thickness at the elevated surface pressures depending on the number of base pairs of the DNA. The results are considered in terms of the electrostatic and hydrophobic interactions, allowing a quantitative conclusion about the arrangement of DNA strands underneath the monolayer of the ILs at the air-water interface.

Surface Functionalization of Poly(lactic acid) via Deposition of Hydroxyapatite Monolayers for Biomedical Applications

The surface modification of poly(lactic acid) (PLA) using hydroxyapatite (HAP) particles via Langmuir-Blodgett (LB) and Langmuir-Schaefer (LS) approaches has been reported. The HAP monolayer was characterized at the air/water interface and deposited on three-dimensional (3D) printed poly(lactic acid). The deposition of HAP particles using the LS approach led to a larger surface coverage in comparison to the LB method, which produces a less uniform coating because of the aggregation of the particles. After the transfer of HAP on the PLA surface, the wettability values remained within the desired range. The presence of HAP on the surface of the polymer altered the topography and roughness in the nanoscale, as evidenced by the atomic force microscopy (AFM) images. This effect can be beneficial for the osteointegration of polymeric implants at an early stage, as well as for the reduction of the adherence of the microbial biofilm. Overall, the results suggest that the LS technique could be a promising approach for surface modification of PLA by hydroxyapatite with respective advantages in the biomedical field.

Bioinspired nanoarchitectonics at the air-water interface to understand the interaction of lipids with a Europium-coordinated quinoline derivative

5SO3H-8-hydroxyquinoline coordinated to Europium (Eu-5SO3-HQ) was incorporated in biomembrane models using Langmuir monolayers. Dipalmitoyl phosphatidylcholine (DPPC) and dipalmitoyl phosphatidylserine (DPPS) were employed, representing mammalian cells and dioctadecyldimethylammonium bromide (DODAB) as a positively charged lipid to study the contrast with negatively charged lipids. Tensiometric, rheological and spectroscopic techniques were employed to characterize Eu-5SO3-HQ- lipid monolayer interactions. The complex condenses all the monolayer indicating interactions with the lipids' polar heads, but with distinctive effects on the mechanical and rheological properties. While the complex decreases the compression and elastic moduli of DPPC and DPPS monolayers, it increases for DODAB, also decreasing its lateral viscosity. Infrared spectroscopy shows that the interaction of Eu-5-SO3-HQ alters the ordering of the lipids' alkyl chains, impacting the monolayer's molecular packing. These results show that the interaction of Eu-5SO3-HQ with lipid monolayers at the air-water is modulated by the composition of the polar head, which can be supportive in the preparation of nanodevices for molecular probing.

Liquid-Liquid Interfacial Nanoarchitectonics

Science in the small world has become a crucial key that has the potential to revolutionize materials technology. This trend is embodied in the postnanotechnology concept of nanoarchitectonics. The goal of nanoarchitectonics is to create bio-like functional structures, in which self-organized and hierarchical structures are working efficiently. Liquid-liquid interface like environments such as cell membrane surface are indispensable for the expression of biological functions through the accumulation and organization of functional materials. From this viewpoint, it is necessary to reconsider the liquid-liquid interface as a medium where nanoarchitectonics can play an active role. In this review, liquid-liquid interfacial nanoarchitectonics is classified by component materials such as organic, inorganic, carbon, and bio, and recent research examples are discussed. Examples discussed in this paper include molecular aggregates, supramolecular polymers, conductive polymers film, crystal-like capsules, block copolymer assemblies, covalent organic framework (COF) films, complex crystals, inorganic nanosheets, colloidosomes, fullerene assemblies, all-carbon π-conjugated graphite nanosheets, carbon nanoskins and fullerphene thin films at liquid-liquid interfaces. Furthermore, at the liquid-liquid interface using perfluorocarbons and aqueous phases, cell differentiation controls are discussed with the self-assembled structure of biomaterials. The significance of liquid-liquid interfacial nanoarchitectonics in the future development of materials will then be discussed.

Stimuli-Responsive Langmuir Films Composed of Nanoparticles Decorated with Poly(N-isopropyl acrylamide) (PNIPAM) at the Air/Water Interface

The nanotechnology shift from static toward stimuli-responsive systems is gaining momentum. We study adaptive and responsive Langmuir films at the air/water interface to facilitate the creation of two-dimensional (2D) complex systems. We verify the possibility of controlling the assembly of relatively large entities, i.e., nanoparticles with diameter around 90 nm, by inducing conformational changes within an about 5 nm poly(N-isopropyl acrylamide) (PNIPAM) capping layer. The system performs reversible switching between uniform and nonuniform states. The densely packed and uniform state is observed at a higher temperature, i.e., opposite to most phase transitions, where more ordered phases appear at lower temperatures. The induced nanoparticles' conformational changes result in different properties of the interfacial monolayer, including various types of aggregation. The analysis of surface pressure at different temperatures and upon temperature changes, surface potential measurements, surface rheology experiments, Brewster angle microscopy (BAM), and scanning electron microscopy (SEM) observations are accompanied by calculations to discuss the principles of the nanoparticles' self-assembly. Those findings provide guidelines for designing other adaptive 2D systems, such as programable membranes or optical interfacial devices.

Assembling Triphenylene-Based Metal-Organic Framework Nanosheets at the Air/Liquid Interface: Modification by Tuning the Spread Solution Concentration

Metal-organic frameworks (MOFs)─crystalline coordination polymers─with unique characteristics such as structural designability accompanied by tunable electronic properties and intrinsic uniform nanopores have become the platform for applications in diverse scientific areas ranging from nanotechnology to energy/environmental sciences. To utilize the superior features of MOF in potential applications, the fabrication and integration of thin films are of importance and have been actively sought. Especially, downsized MOFs into nanosheets can act as ultimately thin functional components in nanodevices and potentially display unique chemical/physical properties rarely seen in bulk MOFs. Assembling nanosheets by aligning amphiphilic molecules at the air/liquid interface has been known as the Langmuir technique. By utilizing the air/liquid interface as a reaction field between metal ions and organic ligands, MOFs are readily formed into the nanosheet state. The expected features in MOF nanosheets including electrical conduction largely depend on the nanosheet characteristics such as lateral size, thickness, morphology, crystallinity, and orientation. However, their control has not been achieved as yet. Here, we demonstrate how changing the concentration of a ligand spread solution can modify the assembly of MOF nanosheets, composed of 2,3,6,7,10,11-hexaiminotriphenylene (HITP) and Ni²⁺ ions (HITP-Ni-NS), at the air/liquid interface. A systematic increase in the concentration of the ligand spread solution leads to the enlargement of both the lateral size and the thickness of the nanosheets while retaining their perfect alignment and preferred orientation. On the other hand, at much higher concentrations, we find that unreacted ligand molecules are included in HITP-Ni-NS, introducing disorder in HITP-Ni-NS. These findings can develop further sophisticated control of MOF nanosheet features, accelerating fundamental and applied studies on MOFs.

Molecular nanoarchitectonics: unification of nanotechnology and molecular/materials science

The development of nanotechnology has provided an opportunity to integrate a wide range of phenomena and disciplines from the atomic scale, the molecular scale, and the nanoscale into materials. Nanoarchitectonics as a post-nanotechnology concept is a methodology for developing functional material systems using units such as atoms, molecules, and nanomaterials. Especially, molecular nanoarchitectonics has been strongly promoted recently by incorporating nanotechnological methods into organic synthesis. Examples of research that have attracted attention include the direct observation of organic synthesis processes at the molecular level with high resolution, and the control of organic syntheses with probe microscope tips. These can also be considered as starting points for nanoarchitectonics. In this review, these examples of molecular nanoarchitectonics are introduced, and future prospects of nanoarchitectonics are discussed. The fusion of basic science and the application of practical functional materials will complete materials chemistry for everything.

The Combined Effects of an External Field and Novel Functional Groups on the Structural and Electronic Properties of TMDs/Ti3C2 Heterostructures: A First-Principles Study

The stacking of Ti₃C₂ with transition metal dihalide (TMDs) materials is an effective strategy to improve the physical properties of a single material, and the tuning of the related properties of these TMDs/Ti₃C₂ heterostructures is also an important scientific problem. In this work, we systematically investigated the effects of an external field and novel functional groups (S, Se, Cl, Br) on the structural and electronic properties of TMDs/Ti₃C₂X₂ heterostructures. The results revealed that the lattice parameters and interlayer distance of TMDs/Ti₃C₂ increased with the addition of functional groups. Both tensile and compressive strain obviously increased the interlayer distance of MoS₂/Ti₃C₂X₂ (X = S, Se, Cl, Br) and MoSe₂/Ti₃C₂X₂ (X = Se, Br). In contrast, the interlayer distance of MoSe₂/Ti₃C₂X₂ (X = S, Cl) decreased with increasing compressive strain. Furthermore, the conductivity of TMDs/Ti₃C₂ increased due to the addition of functional groups (Cl, Br). Strain caused the bandgap of TMDs to narrow, and effectively adjusted the electronic properties of TMDs/Ti₃C₂X₂. At 9% compressive strain, the conductivity of MoSe₂/Ti₃C₂Cl₂ increased significantly. Meanwhile, for TMDs/Ti₃C₂X₂, the conduction band edge (CBE) and valence band edge (VBE) at the M and K points changed linearly under an electric field. This study provides valuable insight into the combined effects of an external field and novel functional groups on the related properties of TMDs/Ti₃C₂X₂.

Dual-Responsive and Reusable Optical Sensors Based on 2,3-Diaminoquinoxalines for Acidity Measurements in Low-pH Aqueous Solutions

This work is focused on the age-old challenge of developing optical sensors for acidity measurements in low-pH aqueous solutions (pH < 5). We prepared halochromic (3-aminopropyl)amino-substituted quinoxalines QC1 and QC8 possessing different hydrophilic-lipophilic balance (HLB) and investigated them as molecular components of pH sensors. Embedding the hydrophilic quinoxaline QC1 into the agarose matrix by sol-gel process allows for fabrication of pH responsive polymers and paper test strips. The emissive films thus obtained can be used for a semi-quantitative dual-color visualization of pH in aqueous solution. Being exposed to acidic solutions with pH in the range of 1-5, they rapidly give different color changes when the analysis is performed in daylight or under irradiation at 365 nm. Compared with classical non-emissive pH indicators, these dual-responsive pH sensors allow for an increase in the accuracy of pH measurements, particularly in complex environmental samples. pH indicators for quantitative analysis can be prepared by the immobilization of amphiphilic quinoxaline QC8 using Langmuir-Blodgett (LB) and Langmuir-Schäfer (LS) techniques. Compound QC8 possessing two long alkyl chains (n-C₈H₁₇) forms stable Langmuir monolayers at the air-water interface, and these monolayers can be successfully transferred onto hydrophilic quartz and hydrophobic polyvinylchlorid (PVC) substrates using LB and LS techniques, respectively. The 30-layer films thus obtained are emissive, reveal excellent stability, and can be used as dual-responsive pH indicators for quantitative measurements in real-world samples with pH in the range of 1-3. The films can be regenerated by immersing them in basic aqueous solution (pH = 11) and can be reused at least five times.

Supramolecular Control of Photonic Response and Sensing of Nitricoxide using Iron(III) Corrole Monolayers and Their Stacks

In this work, we assemble amphiphilic iron(III) corroles at air-water interfaces into well-defined quasi-two-dimensional molecular monolayers and theirs stacks for sensing of nitric oxide (NO). For this purpose, we use the Langmuir-Blodgett (LB) technique, which allows varying the packing density of iron(III) corroles anchored to the aqueous subphase via one molecular side. The stacks of ten down to three molecular monolayers on the front and back sides of the substrates are sufficiently optically dense to detect NO binding to the layers photometrically. This sensing with few layers demonstrates the potential for electronic detection, where very thin surface functionalizations enable efficient electronic communication between the layer and the (semi)conductor. Despite increasing optical densities, the spectral responses to NO exposure become smaller with increasing packing density until the collapse point of the monolayers is reached. This demonstrates that the highest molecular efficiency for binding and detection of NO is achieved at the smallest packing densities. This finding is relevant to all molecular sensor films with axial binding of analytes to the sensor molecules and demonstrates the advantage of sensor molecule assembly into monolayers on water-air interfaces using the LB technique.

Deciphering pressure-induced nanoarchitectonics in a monolayer of heterocoronene-based discotics at air-water and air-solid interfaces

Understanding and control of molecular alignment at the nanoscale in self-assembled supramolecular structures is a prerequisite for the subsequent exploitation of molecules in functional devices. Here, we have clarified the surface-pressure induced molecular nanoarchitectures in a monolayer of a heterocoronene-based discotic liquid crystal (DLC) at air-water and air-solid interfaces using surface manometry, real-time Brewster angle microscopy, and real-space atomic force microscopy (AFM). Chloroform-spread DLCs at a concentration of ∼108 μM exhibit floating domains at the air-water interface comprising small aggregates of edge-on stacked molecules interacting via peripheral alkyl chains. Detailed analysis of surface manometry and relaxation measurements reveal that, upon compression, these domains coalesce to form a coherent monolayer which then undergoes irreversible structural transformations via mechanisms such as monolayer loss due to desorption and localized nucleation of defects. AFM images of the films transferred on a hydrophilic substrate reveal that with increasing surface-pressure, the nanoscale structure of the monolayer transforms from randomly oriented nanowires to tightly-packed nanowire domains, and finally to fragmented wire segments which diffuse locally above the film. These results provide a facile method for the preparation of compact, two-dimensional films of ambipolar DLC molecules with a tunable nanoarchitecture which will be crucial for their applications in nanoscale electronic devices.

Langmuir and Langmuir-Blodgett Films of Gold and Silver Nanoparticles

Recently the focus of the Langmuir-Blodgett technique as a method of choice to transfer monolayers from the air/water interface onto solid substrates in a controllable fashion has been shifting toward purely hydrophobic gold and silver nanoparticles. The fundamental interactions between particles that become relevant in the absence of polar groups range from dispersive attractions from the metal cores and repulsions between ligand shells to weaker entropic factors. The layer evolution is explored, starting with interfacial self-assembly upon solution spreading and domain and circular island formation, which subsequently merge into a complete monolayer and finally form multilayers or macroscopic wrinkles. Moreover, structural properties such as the core:ligand size ratio are investigated in the context of dispersive forces, whereby the nanoparticles with small cores and long ligands tend not to aggregate sufficiently to produce continuous films, those with large cores and short ligands were found to aggregate irreversibly, and those in between the two extremes were concluded to be able to form highly organized crystalline films. Similarly, the characteristics of the spreading solution such as the concentration and the solvent type crucially influence the film crystallinity, with the deciding factor being the degree of affinity between the capping ligand and the solvent used for spreading. Finally, the most common strategies employed to enhance the mechanical stability of the metal nanoparticle films along with the recent attempts to functionalize the particles in attempts to improve their applicability in the industry are summarized and evaluated in relation to their future prospects. One of the objectives of this feature article is to elucidate the differences between hydrophobic metal nanoparticles and typical amphiphilic molecules that the majority of the literature in the field describes and to familiarize the reader with the knowledge required to design Langmuir-Blodgett nanoparticle systems as well as the strategies to improve existing ones.

Perspectives on weak interactions in complex materials at different length scales

Nanocomposite materials consist of nanometer-sized quantum objects such as atoms, molecules, voids or nanoparticles embedded in a host material. These quantum objects can be exploited as a super-structure, which can be designed to create material properties targeted for specific applications. For electromagnetism, such targeted properties include field enhancements around the bandgap of a semiconductor used for solar cells, directional decay in topological insulators, high kinetic inductance in superconducting circuits, and many more. Despite very different application areas, all of these properties are united by the common aim of exploiting collective interaction effects between quantum objects. The literature on the topic spreads over very many different disciplines and scientific communities. In this review, we present a cross-disciplinary overview of different approaches for the creation, analysis and theoretical description of nanocomposites with applications related to electromagnetic properties.

Bifacial Dye Membranes: Ultrathin and Free-Standing although not Being Covalently Bound

Layers of aligned dyes are key to photo-driven charge separation in dye sensitized solar cells, but cannot be exploited as rectifying membranes in photocatalysis to separate half-cells because they are not sufficiently stable. While impressive work on the fabrication of stable noncovalent membranes has been recently demonstrated, these membranes are inherently suffering from non-uniform orientation of the constituting dyes. To stabilize layers made from uniformly assembled and aligned dyes, they can be covalently cross-linked via functional groups or via chromophores at the expense of their optical properties. Here stable membranes from established dyes are reported that do not need to be elaborately functionalized nor do their chromophores need to be destroyed. These membranes are free-standing, although being only non-covalently linked. To enable uniform dye-alignment, Langmuir layers made from linear, water-insoluble dyes are used. That water-soluble charge transfer dyes adsorb onto and intercalate into the Langmuir layer from the aqueous subphase, thus yielding free-standing, molecularly thin membranes are demonstrated. The developed bifacial layers consist almost entirely of π-conjugated units and thus can conduct charges and can be further engineered for optoelectronic and photocatalytic applications.

Biomass Nanoarchitectonics for Supercapacitor Applications

Nanoarchitectonics integrates nanotechnology with numerous scientific disciplines to create innovative and novel functional materials from nano-units (atoms, molecules, and nanomaterials). The objective of nanoarchitectonics concept is to develop functional materials and systems with rationally architected functional units. This paper explores the progress and potential of this field using biomass nanoarchitectonics for supercapacitor applications as examples of energetic materials and devices. Strategic design of nanoporous carbons that exhibit ultra-high surface area and hierarchically pore architectures comprising micro- and mesopore structure and controlled pore size distributions are of great significance in energy-related applications, including in high-performance supercapacitors, lithium-ion batteries, and fuel cells. Agricultural wastes or natural biomass are lignocellulosic materials and are excellent carbon sources for the preparation of hierarchically porous carbons with an ultra-high surface area that are attractive materials in high-performance supercapacitor applications due to high electrical and ion conduction, extreme porosity, and exceptional chemical and thermal stability. In this review, we will focus on the latest advancements in the fabrication of hierarchical porous carbon materials from different biomass by chemical activation method. Particularly, the importance of biomass-derived ultra-high surface area porous carbons, hierarchical architectures with interconnected pores in high-energy storage, and high-performance supercapacitors applications will be discussed. Finally, the current challenges and outlook for the further improvement of carbon materials derived from biomass or agricultural wastes in the advancements of supercapacitor devices will be discussed.

Molecular Machines and Microrobots: Nanoarchitectonics Developments and On-Water Performances

This review will focus on micromachines and microrobots, which are objects at the micro-level with similar machine functions, as well as nano-level objects such as molecular machines and nanomachines. The paper will initially review recent examples of molecular machines and microrobots that are not limited to interfaces, noting the diversity of their functions. Next, examples of molecular machines and micromachines/micro-robots functioning at the air-water interface will be discussed. The behaviors of molecular machines are influenced significantly by the specific characteristics of the air-water interface. By placing molecular machines at the air-water interface, the scientific horizon and depth of molecular machine research will increase dramatically. On the other hand, for microrobotics, more practical and advanced systems have been reported, such as the development of microrobots and microswimmers for environmental remediations and biomedical applications. The research currently being conducted on the surface of water may provide significant basic knowledge for future practical uses of molecular machines and microrobots.

Lanthanide-Based Langmuir–Blodgett Multilayers: Multi-Emissive, Temperature-Dependent Thin Films

Multi-emissive compounds have attracted significant attention from the research community owing to the wide array of potential application areas. However, to move towards application, such systems should be readily immobilized by solution-based methods to form soft materials such as gels and films. Herein we report the use of Langmuir–Blodgett (LB) deposition to easily immobilize luminescent lanthanide-based amphiphilic solids into multi-emissive ultrathin LB films, by multilayering different luminescent amphiphiles. Utilizing this technique, we have reliably fabricated dual- and triple-emissive films where the overall emission from the film is tuned. Furthermore, we have demonstrated that these multi-emissive films are temperature-dependent, with emission profiles significantly altering from 294 to 340 K, resulting in colour changes and potential application as ultrathin, contactless ratiometric thermometer coatings.

Aggregation behavior and spectroscopic properties of red-emitting distyryl-BODIPY in aqueous solution, Langmuir-Schaefer films and Pluoronic® F127 micelles

Red-emitting distyryl substituted BODIPY dyes are among the most promising luminophors for bioimaging and optics applications. However, the practical application of BODIPYs is limited due to their high hydrophobicity and tendency to aggregate in aqueous organic solutions and solid phase. In this article, we propose an elegant solution to this problem. To this end, we carried out the detailed experimental and quantum-chemical study of the structural and spectral features of BF₂-ms-phenyl-5,5'-bis(4-dimethylaminostyryl)-3,3'-dimethyl-2,2'-dipyrromethene (distyryl-BDP). The particular attention was paid to analysis of high sensitivity of the distyryl-BDP spectral characteristics to the solvent properties, and also the aggregation behavior features both in water-organic media and in mono- and multilayer Langmuir-Schaefer films. We selected the best conditions to obtain the hydrophilic micellar structures of distyryl-BDP with Pluronic® F127 having a high efficiency of dye solubilization. This method increasing the solubility improves the distyryl-BDP transport efficiency in physiological aqueous media. The aqueous solutions of distyryl-BDP-Pl micelles show the intense fluorescence in the phototherapy window region (λ_fl = 739 nm).

On the Preparation of Thin Films of Stearyl Methacrylate Directly Photo-polymerized at the Air-Water Interface

Characterization of bidimensional polymeric films at the air-water interface in the Langmuir trough, despite being a recurrent topic, usually refers to films of already formed polymeric materials, with very scarce reports on direct polymerization at the air-water interface. In the present work, we studied the photo-polymerization of stearyl methacrylate directly at the air-water interface under a nitrogen atmosphere, with the radical initiator solubilized in the aqueous phase. Two-dimensional (2D) polymerization was monitored by measuring the pressure-area isotherm at different irradiation times. The polymerization leads to a film with an isotherm different from that observed for the monomer, where the surface pressure is directly related to the irradiation time. The shape of this isotherm confirms the presence of a compressed liquid phase, where a higher order can be attained as a consequence of stronger packing forces involving polymer chains. The presence of inter-chain interactions allows rearrangements on the surface of the subphase, and even before the collapse a dense 2D ordering (with a solid phase-like behavior) can be observed. We present a new one-step, solvent-free procedure to obtain a photo-polymeric film directly at the air-water interface, which can be transferred to a solid surface by the Langmuir-Blodgett method, allowing film preparation of controlled thickness. Films were characterized by measuring properties such as thickness, roughness, and hydrophobicity and comparing them with films obtained from a conventional polymer. We report the differences between the interfacial behavior of amphiphilic molecules and nanomaterials such as films obtained by photo-polymerization, PSMA, directly on the air-water interface.

Comprehensive Approach to the Interpretation of the Electrical Properties of Film-Forming Molecules

This paper presents a general protocol for the interpretation of the electric surface potential of Langmuir monolayers based on a three-layer capacitor model. The measured values were correlated with the results from DFT molecular dynamics simulations, and, as a result, the local dielectric permittivities and dipole-moment components of molecules organized in the monolayer were obtained. The main advantage of the developed approach is applicability to amphiphiles of any type; irrespective of the structure of the polar head as well as the molecular organization and inclination in the surface film. The developed methodology was successively applied to an atypical surface-active compound, perfluorodecyldecane, and its derivatives containing the hydroxyl, thiol, and carboxyl moiety. The following contributions to the apparent dipole moments connected with the reorientation of water molecules and local dielectric permittivities in the vicinity of polar and apolar molecule parts, respectively, were determined: μ^w/ε_w = −0.85 D, ε_p = 5.00, and ε_a = 1.80. Moreover, the investigated perfluorodecyldecane derivatives were comprehensively characterized in terms of their surface activity, film rheology, and effective surface dissociation equilibria. The proposed methodology may be crucial for the process of the design and the preliminary characterization of molecules for sensor and material science applications.

On the Interfacial Behavior of Catenated Poly(l-lactide) at the Air-Water Interface

Interfacial properties of polymeric materials are significantly influenced by their architectural structures and spatial features, while such a study of topologically interesting macromolecules is rarely reported. In this work, we reported, for the first time, the interfacial behavior of catenated poly(l-lactide) (C-PLA) at the air-water interface and compared it with its linear analogue (L-PLA). The isotherms of surface pressure-area per repeating unit showed significant interfacial behavioral differences between the two polymers with different topologies. Isobaric creep experiments and compression-expansion cycles also showed that C-PLA demonstrated higher stability at the air-water interface. Interestingly, when the films at different surface pressures were transferred via the Langmuir-Blodgett method, successive atomic force microscopy imaging displayed distinct nanomorphologies, in which the surface of C-PLA exhibited nanofibrous structures, while that of the L-PLA revealed a smoother topology with less fiber-like structures.

Molecule-to-Material-to-Bio Nanoarchitectonics with Biomedical Fullerene Nanoparticles

Nanoarchitectonics integrates nanotechnology with various other fields, with the goal of creating functional material systems from nanoscale units such as atoms, molecules, and nanomaterials. The concept bears strong similarities to the processes and functions seen in biological systems. Therefore, it is natural for materials designed through nanoarchitectonics to truly shine in bio-related applications. In this review, we present an overview of recent work exemplifying how nanoarchitectonics relates to biology and how it is being applied in biomedical research. First, we present nanoscale interactions being studied in basic biology and how they parallel nanoarchitectonics concepts. Then, we overview the state-of-the-art in biomedical applications pursuant to the nanoarchitectonics framework. On this basis, we take a deep dive into a particular building-block material frequently seen in nanoarchitectonics approaches: fullerene. We take a closer look at recent research on fullerene nanoparticles, paying special attention to biomedical applications in biosensing, gene delivery, and radical scavenging. With these subjects, we aim to illustrate the power of nanomaterials and biomimetic nanoarchitectonics when applied to bio-related applications, and we offer some considerations for future perspectives.

Materials nanoarchitectonics in a two-dimensional world within a nanoscale distance from the liquid phase

Promoted understanding of nanotechnology has enabled the construction of functional materials with nanoscale-regulated structures. Accordingly, materials science requires one-step further innovation by coupling nanotechnology with the other materials sciences. As a post-nanotechnology concept, nanoarchitectonics has recently been proposed. It is a methodology to architect functional material systems using atomic, molecular, and nanomaterial unit-components. One of the attractive methodologies would be to develop nanoarchitectonics in a defined dimensional environment with certain dynamism, such as liquid interfaces. However, nanoarchitectonics at liquid interfaces has not been fully explored because of difficulties in direct observations and evaluations with high-resolutions. This unsatisfied situation in the nanoscale understanding of liquid interfaces may keep liquid interfaces as unexplored and attractive frontiers in nanotechnology and nanoarchitectonics. Research efforts related to materials nanoarchitectonics on liquid interfaces have been continuously made. As exemplified in this review paper, a wide range of materials can be organized and functionalized on liquid interfaces, including organic molecules, inorganic nanomaterials, hybrids, organic semiconductor thin films, proteins, and stem cells. Two-dimensional nanocarbon sheets have been fabricated by molecular reactions at dynamically moving interfaces, and metal-organic frameworks and covalent organic frameworks have been fabricated by specific interactions and reactions at liquid interfaces. Therefore, functions such as sensors, devices, energy-related applications, and cell control are being explored. In fact, the potential for the nanoarchitectonics of functional materials in two-dimensional nanospaces at liquid surfaces is sufficiently high. On the basis of these backgrounds, this short review article describes recent approaches to materials nanoarchitectonics in a liquid-based two-dimensional world, i.e., interfacial regions within a nanoscale distance from the liquid phase.

Strong and Elastic Membranes via Hydrogen Bonding Directed Self-Assembly of Atomically Precise Nanoclusters

2D nanomaterials have provided an extraordinary palette of mechanical, electrical, optical, and catalytic properties. Ultrathin 2D nanomaterials are classically produced via exfoliation, delamination, deposition, or advanced synthesis methods using a handful of starting materials. Thus, there is a need to explore more generic avenues to expand the feasibility to the next generation 2D materials beyond atomic and molecular-level covalent networks. In this context, self-assembly of atomically precise noble nanoclusters can, in principle, suggest modular approaches for new generation 2D materials, provided that the ligand engineering allows symmetry breaking and directional internanoparticle interactions. Here the self-assembly of silver nanoclusters (NCs) capped with p-mercaptobenzoic acid ligands (Na₄ Ag₄₄ -pMBA₃₀ ) into large-area freestanding membranes by trapping the NCs in a transient solvent layer at air-solvent interfaces is demonstrated. The patchy distribution of ligand bundles facilitates symmetry breaking and preferential intralayer hydrogen bondings resulting in strong and elastic membranes. The membranes with Young's modulus of 14.5 ± 0.2 GPa can readily be transferred to different substrates. The assemblies allow detection of Raman active antibiotic molecules with high reproducibility without any need for substrate pretreatment.

Langmuir-Blodgett Deposition of Cellulose Nanocrystal Surfactants into Ordered Monolayers

The cellulose nanocrystals (CNCs) are shown to interact with amine-functionalized polyhedral oligomeric silsesquioxane (POSS-NH₂) strongly at the water/oil interface, forming the CNC-POSS assemblies, that is, CNC surfactants that decrease the interfacial tension of the water/chloroform greatly. When bringing the CNC aqueous solution and POSS chloroform solution into a Langmuir trough, they form a monolayer of the CNC surfactants. Upon applying a continuous compression, a distinct transition appears in the surface pressure-area curves, and during this transition, the packing of the CNC surfactants in the produced monolayers transits from network-like patterns to ordered alignment.

Dominant hydrophobic interactions with β-glucan in nanoarchitectonics with mixed Langmuir monolayers of cholesterol/dipalmitoyl phosphatidyl choline

The polysaccharide β-glucan, found in the cell wall of cereals such as wheat, oats, and barley, is believed to lower the concentration of bad cholesterol in humans, but the molecular-level mechanisms responsible for such an action are unknown. In this study, we use Langmuir monolayers of cholesterol and dipalmitoyl phosphatidyl choline (DPPC) as cell membrane models that are made to interact with β-glucan. Neat cholesterol and mixed cholesterol/DPPC monolayers were expanded upon incorporating β-glucan from the aqueous subphase. This incorporation was found to induce ordering in mixed monolayers and dehydration of the carbonyl group at higher cholesterol concentrations. These effects are attributed to hydrophobic interactions as identified with polarization-modulated infrared reflection-absorption spectroscopy. They correlate well with the hypothesis that cholesterol levels can be lowered by the formation of soluble fibers with β-glucan through hydrophobic interactions, blocking cholesterol absorption by the organism.

Mechanical Tuning of Aggregated States for Conformation Control of Cyclized Binaphthyl at the Air-Water Interface

An air-water interface enables molecular assemblies and conformations to be controlled according to their intrinsic interactions and anisotropic stimuli. The chirality and conformation of binaphthyl derivatives have been controlled by tuning molecular aggregated states in solution. In this study, we have tuned molecular aggregated states of monobinaphthyldurene (MBD) by applying different mechanical stimuli to control the conformation at the air-water interface. Density functional theory calculations indicate that MBD exists essentially in two conformations, namely, 1-MBD (most stable) and 2-MBD (less stable). MBD was mechanically dissolved in appropriate lipid matrices using the Langmuir-Blodgett (LB) method, while pure MBD was self-assembled at the dynamic air-water interface in the absence of or by applying vortex motions (vortex LB method). In MBD mixed monolayer, surface pressure-molecular area measurements and atomic force microscopy observations suggest that separate lipids and MBD phases transform to mixed phases induced by the dissolution of MBD into the lipid matrices during mechanical compression at the air-water interface. Circular dichroism measurements indicate that molecular conformation changes from 1-MBD to 2-MBD in passing from a separated phase to a mixed MBD/lipid phase. In addition, the molecular aggregated states and conformations of MBD depend on the spreading volume and vortex flow rate when applying the vortex LB method. Molecular conformations and aggregated states of MBD could be controlled continuously by applying a mechanical stimulus at the air-water interface.

Hyper 100 °C Langmuir-Blodgett (Langmuir-Schaefer) Technique for Organized Ultrathin Film of Polymeric Semiconductors

In this study, we advanced the conventional Langmuir-Blodgett (LB) method to a high-temperature range (above 100 °C) using a newly manufactured LB machine, which is adaptable to a high-boiling-point subphase, as a universally usable apparatus. A sophisticated trough design, with homogeneous heating capability up to approximately 200 °C, together with automatic film compression and Langmuir-Schaefer type film transfer, enabled the fabrication of highly aligned thin films of polymeric semiconductors with uniaxial alignment of polymer backbones, which is desirable for efficient charge transport. Herein, ultrathin films of semicrystalline thiophene-based semiconductors were prepared on ethylene glycol and heated to 80 °C. The analyses of the transferred films with pressure-area isotherms, atomic force microscopy (AFM), polarized optical microscopy (POM), and grazing-incidence wide-angle X-ray scattering (GIWAXS) indicated that the proposed high-temperature LB method allows ideal deposition of high-quality ultrathin films with molecular layer precision at the selected high-temperature conditions. Furthermore, preparing thin-film donor-acceptor-type copolymers in ionic liquids at high temperatures (up to 140 °C) was a challenging task that was successfully demonstrated in this study. Highly ordered thin films of donor-acceptor polymers with a uniaxial backbone orientation were obtained only at 140 °C. The obtained semicrystalline thin films with uniaxially aligned polymer backbones significantly contribute to the two-dimensional overlap of molecular orbitals, which is likely to promote charge transport. The use of the manufactured automatic LB machines is advantageous for better quality films prepared at higher temperatures (even above 100 °C) from various technical viewpoints, including homogeneous heating, constant compression, and automatic film transfer. The novel methodology proposed herein expands the possibilities of the Hyper 100 °C Langmuir-Blodgett technique, which has not been accessible by the conventional LB method with the aqueous subphase.

Mechano-Nanoarchitectonics: Design and Function

Mechanical stimuli have rather ambiguous and less-specific features among various physical stimuli, but most materials exhibit a certain level of responses upon mechanical inputs. Unexplored sciences remain in mechanical responding systems as one of the frontiers of materials science. Nanoarchitectonics approaches for mechanically responding materials are discussed as mechano-nanoarchitectonics in this review article. Recent approaches on molecular and materials systems with mechanical response capabilities are first exemplified with two viewpoints: i) mechanical control of supramolecular assemblies and materials and ii) mechanical control and evaluation of atom/molecular level structures. In the following sections, special attentions on interfacial environments for mechano-nanoarchitectonics are emphasized. The section entitled iii) Mechanical Control of Molecular System at Dynamic Interface describes coupling of macroscopic mechanical forces and molecular-level phenomena. Delicate mechanical forces can be applied to functional molecules embedded at the air-water interface where operation of molecular machines and tuning of molecular receptors upon macroscopic mechanical actions are discussed. Finally, the important role of the interfacial media are further extended to the control of living cells as described in the section entitled iv) Mechanical Control of Biosystems. Pioneering approaches on cell fate regulations at liquid-liquid interfaces are discussed in addition to well-known mechanobiology.