Nanoarchitectonics in combat against bacterial infection using molecular,interfacial, and material tools

Nanoarchitectonics, as a post-nanotechnology concept, is the methodology for constructing functional materials from nano-units, which bridges the gap between nanotechnology and materials science. The research accomplishes advocating nanoarchitectonics has increased dramatically as overviewed in the initial part of this review. Then, as socially impactful subjects, we exemplify nanoarchitectonics research for bacterial infections according to classifications featured with molecular tools, interfaces, and hierarchically structured materials. In particular, this review article discusses namely three kinds of antibacterial strategies: (i) new antimicrobial agents and therapeutic modalities based on nanoarchitectonics present high bactericidal efficacy against methicillin-resistant Staphylococcus aureus; (ii) antimicrobial nanoarchitectonics structures are integrated into the surface of medical devices to detach or kill approaching bacteria; (iii) the nanoarchitectonics hydrogels act as antimicrobial reservoirs to produce sustained-release antimicrobial agents for long-lasting bacterial killing.     

2D Nanoarchitectonics: Soft Interfacial Media as Playgrounds for Microobjects,Molecular Machines,and Living Cells

Soft and flexible two-dimensional (2D) systems, such as liquid interfaces, would have much more potentials in dynamic regulation on nano–macro connected functions. In this Minireview article, we focus especially on dynamic motional functions at liquid dynamic interfaces as 2D material systems. Several recent examples are selected to be explained for overviewing features and importance of dynamic soft interfaces in a wide range of action systems. The exemplified research systems are mainly classified into three categories: (i) control of microobjects with motional regulations; (ii) control of molecular machines with functions of target discrimination and optical outputs; (iii) control of living cells including molecular machine functions at cell membranes and cell/biomolecular behaviors at liquid interface. Sciences on soft 2D media with motional freedom and their nanoarchitectonics constructions will have increased importance in future technology in addition to popular rigid solid 2D materials.     

Nanoarchitectonics from Atom to Life

Functional materials with rational organization cannot be directly created only by nanotechnology‐related top‐down approaches. For this purpose, a novel research paradigm next to nanotechnology has to be established to create functional materials on the basis of deep nanotechnology knowledge. This task can be assigned to an emerging concept, nanoarchitectonics. In the nanoarchitectonics approaches, functional materials are architected through combination of atom/molecular manipulation, organic chemical synthesis, self‐assembly and related spontaneous processes, field‐applied assembly, micro/nano fabrications, and bio‐related processes. In this short review article, nanoarchitectonics‐related approaches on materials fabrications and functions are exemplified from atom‐scale to living creature level. Based on their features, unsolved problems for future developments of the nanoarchitectonics concept are finally discussed.     

Progress in Molecular Nanoarchitectonics and Materials Nanoarchitectonics

Although various synthetic methodologies including organic synthesis, polymer chemistry, and materials science are the main contributors to the production of functional materials, the importance of regulation of nanoscale structures for better performance has become clear with recent science and technology developments. Therefore, a new research paradigm to produce functional material systems from nanoscale units has to be created as an advancement of nanoscale science. This task is assigned to an emerging concept, nanoarchitectonics, which aims to produce functional materials and functional structures from nanoscale unit components. This can be done through combining nanotechnology with the other research fields such as organic chemistry, supramolecular chemistry, materials science, and bio-related science. In this review article, the basic-level of nanoarchitectonics is first presented with atom/molecular-level structure formations and conversions from molecular units to functional materials. Then, two typical application-oriented nanoarchitectonics efforts in energy-oriented applications and bio-related applications are discussed. Finally, future directions of the molecular and materials nanoarchitectonics concepts for advancement of functional nanomaterials are briefly discussed.     

Interfacial nanoarchitectonics for molecular manipulation and molecular machine operation

The nanoarchitectonics concept enables us to produce functional systems and materials from nanoscale units through nanotechnological approaches together with the processes including chemical syntheses, atom/molecule manipulations, self-assemblies, self-organizations, field-induced material regulations, and bio-related processes. Especially, manipulations of molecules (molecular machines) and sophisticated organization would be attractive targets in interfacial nanoarchitectonics. In this short review, we introduce several typical examples on manipulations of functional molecules and molecular machines at interfacial media. The examples are classified roughly according to driving forces of manipulations; (i) manipulations through chemical reactions and interactions; (ii) light-driven manipulations; (iii) electrically controlled manipulations; (iv) mechanical manipulations. Future possibilities of molecular manipulations at interfaces such as usages in biological systems are discussed in perspective section.     

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.     

Dynamic behaviors of molecular assemblies at liquid/liquid interfaces studied by time-resolved quasi-elastic laser scattering spectroscopy.

The dynamic behaviors of molecular assemblies at two immiscible liquid interfaces are intriguing topics in many fields of science and technology. However, it is generally difficult to investigate the dynamic behaviors of such molecular assemblies because of the buried nature of liquid/liquid interfaces. In the present paper, our recent investigations on dynamic behaviors of various molecular self-assemblies at liquid/liquid interfaces are reviewed. We monitored dynamic behaviors of the molecular assemblies by time-resolved quasi-elastic laser scattering (TR-QELS) and fluorescent spectroscopy. The former method allows us to monitor the change in interfacial tension with millisecond time-resolution. As molecular assemblies, bis(2-ethylhexyl)sulfosuccinate (AOT) microemulsion, phospholipid biomembrane models, and liposome-DNA complexes have all been studied, since they are relevant in material sciences and biological technologies. At liquid/liquid interfaces, these molecular assemblies showed characteristic behaviors. We review the finding of rebound response of the interfacial tension at the liquid/liquid interface induced by the adsorption of the AOT microemulsion. We monitored the hydrolysis reaction of phospholipid biomembrane models formed at oil/water interfaces, observing the different types of behavior of liposome-DNA complexes at biomembrane models with different kinds of phospholipids.     

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.     

隐藏高分子界面及生物界面分子结构的和频振动光谱研究

界面的分子结构决定界面的性质.为了以优化界面的结构来改进材料的性质,原位实时地研究界面的分子结构是很重要的.近年来和频振动光谱已发展成为一个很有效及独特的手段来研究隐藏界面的分子结构,例如液/液界面、固/液界面及固/固界面等.这篇综述讨论了和频振动光谱在研究高分子界面及生物界面等复杂界面的分子结构上的应用.具体说来,本文论述了高分子表面在水里的分子结构变化,高分子及模型粘合促进剂硅烷在界面相互作用的分子机理和隐藏的高分子/高分子及高分子/金属界面的结构.另外,此文还将介绍不同二级结构的多肽及几个有代表性的蛋白分子在界面的结构.界面在诸如化学、生物、物理、材料科学及工程和纳米技术等许多领域都很重要.发展一个独特的能原位研究隐藏界面的分子结构的技术会有力地促进这些领域的研究及跨学科研究的发展.     

Active colloidal particles at fluid-fluid interfaces

This review explores the intersection between two important fields of colloid and interface science – that of active colloidal particles and of (passive) particles at fluid-fluid interfaces. The former uses energy input at the particle level to propel particle motions and direct dynamic assemblies. The latter relies on the spontaneous adsorption of particles at fluid interfaces to modify the interfacial energy, rheology, and permeability of biphasic materials. Here, we address two key questions that connect these otherwise distinct fields of study. How do liquid interfaces influence the dynamics of active or driven colloidal particles? How can particle activity influence the dynamics of liquid interfaces? These questions motivate the pursuit of active particle surfactants that move and organize at fluid interfaces to perform useful functions such as enhancing mass transport or modulating interfacial properties. Drawing examples from the literature, we discuss how fluid interfaces can provide a unique environment for the study of active colloids, how surface tension can be harnessed to propel particle motions, and how capillary interactions can be activated to achieve dynamically tunable emulsions and foams. We highlight opportunities for the future study and application of active particles at liquid interfaces.     

Nanobiotechnology and its role in the development of new analytical devices

Physical methods of molecule observation and manipulation will prove useful, not only as research tools for investigating biomolecular structure and behavior, but also for the creation of nanostructures. Supramolecular and self-assembling structures are able to generate nanostructures, with many such systems being of biological origin. They form the interface between nanotechnology and biotechnology. Whereas biotechnological processes usually involve populations of cells or molecules, nanotechnological methods operate at the level of individual molecule manipulation. This article considers what advances have been made through cross-fertilisation between nanotechnology and biotechnology to develop for the next millennium new analytical tools at the microscale, using nanostructures as the sensitive part and with the ability to detect individual molecules.     

New approaches to liquid interfaces through changes in the refractive index and nonlinear susceptibility utilizing ultrashort laser pulses.

Molecules in inhomogeneous liquid environments, such as air/liquid, liquid/liquid, solid/liquid interfaces interact with each other specifically, and sometimes form characteristic structures and emerge unique properties. Here, we introduce two newly developed spectroscopic techniques, the total-internal-reflection ultrafast transient lens method (TIR-UTL) and second harmonic generation-coherent vibrational spectroscopy (SHG-CVS), to investigate the characteristic behaviors of molecules in such inhomogeneous environments. TIR-UTL probes the refractive-index change with sub-picosecond resolution and provides information on ultrafast changes in the population, density, and thermal properties, such as temperature increase and energy transfer from the solute molecules to the surrounding solvent molecules. On the other hand, SHG-CVS probes nonlinear susceptibility changes at the interfacial areas, and is expected to provide spectroscopic information on the low-frequency vibrational modes that reflect the corrective motion of the molecules in such an inhomogeneous environment. These new approaches are based on pump-probe techniques utilizing (ultra) short laser pulses. They are expected to provide further information on inhomogeneous environments from the viewpoints of solute-solvent interactions, changes in the molecular orientation, and the corrective motion of molecules at liquid interfaces.     

Light scattering near and from interfaces using evanescent wave and ellipsometric light scattering

The broad range of interface light scattering investigations in recent years shows the power and the versatility of these techniques to address new and open questions in colloid and interface science and the soft condensed matter field. Structural information for polymers, liquid crystals, or colloids close to planar or spherical colloidal interfaces are either captured with long range light scattering resolution, or in a complementary approach by high resolution ellipsometric techniques. Of special interest is the dynamic behavior close to or in interfaces, since it determines material properties and responses to external fields. Due to the broad dynamical range and the high scattering contrast for visible light, interface light scattering is a key to elucidate soft matter interfacial dynamics. This contribution reviews experimental and related theoretical approaches for interface light scattering and further gives an overview of achievements based on such techniques.     

Modifying the liquid/liquid interface: pores, particles and deposition

The modification of the liquid/liquid interface with solid phases is discussed in this article. Modified interfaces can be formed with molecular assemblies, but here attention is focussed on solid materials such as mesoscopic particles, or microporous and mesoporous membranes. Charge transfer across the modified liquid/liquid interface is considered in particular. The most obvious consequence of the introduction of such modifying components is their effect on the transport to, and the transfer of material across, the liquid/liquid interface, as measured voltammetrically for example. One particularly interesting reaction is interfacial metal deposition, which can also be studied under electrochemical control: the initial formation of metal nuclei at the interface transforms it from the bare, pristine state to a modified state with very different reactivity. Deposition at interfaces between liquids is compared and contrasted with the cases of metal deposition in bulk solution and conventional heterogeneous deposition on conducting solid surfaces. Comparison is also made with work on the assembly of pre-formed micron and nanometre scale solids at the liquid/liquid interface.     

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.     

蛋白质相互作用: 界面分析, 结合自由能计算与相互作用设计

蛋白质相互作用在生命活动中起着重要作用. 研究蛋白质间相互作用的本质有助于了解生命活动中这些基本单元的作用. 本文主要综述了近期蛋白质相互作用研究的进展, 包括蛋白质相互作用界面的基本性质, 蛋白质结合自由能的计算方法, 不同相互作用在蛋白质结合/解离中的角色和差异, 以及上述知识在蛋白质相互作用设计中的应用. 蛋白质相互作用界面的特性, 例如界面大小、保守性以及结构的动态性质, 使得具有生物功能的蛋白质相互作用界面区别于非特异性的晶体堆积界面. 生物功能界面的一个重要结构特征是界面上存在着关键残基以及相对独立的相互作用模块. 利用多种方法, 如MM-PBSA、统计平均势以及不同的相互作用自由能模型, 可以在不同的精度上计算蛋白质相互作用自由能. 利用蛋白质相互作用界面的特点, 从不同的角度进行蛋白质相互作用对的设计与改造, 近年来已经有了不少成功的例子, 但还存在着很大的挑战. 我们认为在今后的蛋白质相互作用设计中, 考虑各种因素对蛋白质结合与解离的动力学过程的影响将有助于提高人类控制蛋白质相互作用的能力.     

Electrochemistry at micro- and nanoscopic liquid/liquid interfaces

In this tutorial review, we will briefly introduce the history and basic concepts of micro- and nanoscopic liquid/liquid interfaces (size from nm to μm) in electrochemical studies of charge (electron and ion) transfer reactions at soft molecular interfaces. Their advantages and problems are usually compared with those of conventional liquid/liquid interfaces (size from mm to cm); and with solid/electrolyte interfaces. Three methods of fabrication of micro-liquid/liquid interfaces and one approach to support a nano-liquid/liquid interface are surveyed. The experimental and theoretical aspects are discussed along with possible approaches to characterize these micro- and nanoscopic liquid/liquid interfaces, and the methods to modify them with new functionality. Unique examples of applications of electrochemistry at micro- and nanoscopic liquid/liquid interfaces are provided. Some novel and potential research interests in the future in this field are discussed.