KEGG(Kyoto Encyclopedia of Genes and Genomes)〔和文〕 (特集 ゲノム医学の現在と未来--基礎と臨床) -- (データベース)

Supramolecular nanotube architectures based on amphiphilic molecules.

Solid supported lipid bilayers: From biophysical studies to sensor design.

Biofabrication with chitosan.

Kepa Ruiz-Mirazo,†,∥ Carlos Briones,‡,∥ and Andreś de la Escosura* †Biophysics Unit (CSIC-UPV/EHU), Leioa, and Department of Logic and Philosophy of Science, University of the Basque Country, Avenida de Tolosa 70, 20080 Donostia−San Sebastiań, Spain ‡Department of Molecular Evolution, Centro de Astrobiología (CSIC−INTA, associated to the NASA Astrobiology Institute), Carretera de Ajalvir, Km 4, 28850 Torrejoń de Ardoz, Madrid, Spain Organic Chemistry Department, Universidad Autońoma de Madrid, Cantoblanco, 28049 Madrid, Spain

Prebiotic systems chemistry: new perspectives for the origins of life.

Methods based on self-assembly, self-organization, and forced shape transformations to form synthetic or semisynthetic enclosed lipid bilayer structures with several properties similar to biological nanocompartments are reviewed. The procedures offer unconventional micro- and nanofabrication routes to yield complex soft-matter devices for a variety of applications for example, in physical chemistry and nanotechnology. In particular, we describe novel micromanipulation methods for producing fluid-state lipid bilayer networks of nanotubes and surface-immobilized vesicles with controlled geometry, topology, membrane composition, and interior contents. Mass transport in nanotubes and materials exchange, for example, between conjugated containers, can be controlled by creating a surface tension gradient that gives rise to a moving boundary or by induced shape transformations. The network devices can operate with extremely small volume elements and low mass, to the limit of single molecules and particles at a length scale where a continuum mechanics approximation may break down. Thus, we also describe some concepts of anomalous fluctuation-dominated kinetics and anomalous diffusive behaviours, including hindered transport, as they might become important in studying chemistry and transport phenomena in these confined systems. The networks are suitable for initiating and controlling chemical reactions in confined biomimetic compartments for rationalizing, for example, enzyme behaviors, as well as for applications in nanofluidics, bioanalytical devices, and to construct computational and complex sensor systems with operations building on chemical kinetics, coupled reactions and controlled mass transport.

Biomimetic nanoscale reactors and networks.

Cell-cell communication is critical to the development, maintenance, and function of multicellular organisms. Classical mechanisms for intercellular communication include secretion of molecules into the extracellular space and transport of small molecules through gap junctions. Recent reports suggest that cells also can communicate over long distances via a network of transient intercellular nanotubes. Such nanotubes have been shown to mediate intercellular transfer of organelles as well as membrane components and cytoplasmic molecules. Moreover, intercellular nanotubes have been observed in vivo and have been shown to enhance the transmission of pathogens such as human immunodeficiency virus (HIV)-1 and prions in vitro. These studies indicate that intercellular nanotubes may play a role both in normal physiology and in disease.

Intercellular nanotubes: insights from imaging studies and beyond

New markers are constantly emerging that identify smaller and smaller subpopulations of immune cells. However, there is a growing awareness that even within very small populations, there is a marked functional heterogeneity and that measurements at the population level only gives an average estimate of the behaviour of that pool of cells. New techniques to analyze single immune cells over time are needed to overcome this limitation. For that purpose, we have designed and evaluated microwell array systems made from two materials, polydimethylsiloxane (PDMS) and silicon, for high-resolution imaging of individual natural killer (NK) cell responses. Both materials were suitable for short-term studies (<4 hours) but only silicon wells allowed long-term studies (several days). Time-lapse imaging of NK cell cytotoxicity in these microwell arrays revealed that roughly 30% of the target cells died much more rapidly than the rest upon NK cell encounter. This unexpected heterogeneity may reflect either separate mechanisms of killing or different killing efficiency by individual NK cells. Furthermore, we show that high-resolution imaging of inhibitory synapse formation, defined by clustering of MHC class I at the interface between NK and target cells, is possible in these microwells. We conclude that live cell imaging of NK-target cell interactions in multi-well microstructures are possible. The technique enables novel types of assays and allow data collection at a level of resolution not previously obtained. Furthermore, due to the large number of wells that can be simultaneously imaged, new statistical information is obtained that will lead to a better understanding of the function and regulation of the immune system at the single cell level.

Imaging Immune Surveillance of Individual Natural Killer Cells Confined in Microwell Arrays

We present a micropipet-assisted writing technique for formation of two-dimensional networks of phospholipid vesicles and nanotubes on functionalized and patterned substrates. The substrates are patterned with vesicle-adhesive circular spots (5-7.5 µm in diameter) consisting of a basal layer of biotin on gold and an apical coating of NeutrAvidin in a sandwich manner. The area surrounding the adhesive spots is coated with a phosphatidylcholine bilayer membrane, preventing protein and liposome adhesion. Networks were formed by aspirating a biotin-functionalized giant unilamellar or multilamellar liposome (5-50 µm in diameter) into a ~3 µm inner diameter borosilicate glass micropipet. By using a pressurized-air microejection system, a portion of the liposome is then ejected back into the solution while forming a first vesicle ~3 µm in diameter. This vesicle is placed on an adhesive spot. When the micropipet is moved, a nanotube connection is formed from the first vesicle and is pulled to the next adhesive spot where a second vesicle is ejected. This procedure can then be repeated until the lipid material is consumed in the pipet. The method allows for formation of networks with a large number of nodes and vertexes with well-defined geometry and surface adhesion, and represents a first step toward very large scale integration of nanotube-vesicle networks in, for example, nanofluidic applications.

Micropipet Writing Technique for Production of Two-Dimensional Lipid Bilayer Nanotube−Vesicle Networks on Functionalized and Patterned Surfaces

The microinjection of bacteria (the MG1655 strain of E. coli) into unilamellar lipid vesicles contained in surface-immobilized nanotube–vesicle networks is demonstrated. The density of bacteria can be controlled from a single bacterium up to several thousands of bacteria per injected vesicle. The bacteria retain flagellar motion and propulsion. The bacteria (approximately 2 × 0.8 μm) cannot escape from one vesicle to another as the size of the nanotubes is too small (∼200 nm in diameter) to allow for entry. Bacteria can, however, be moved from one vesicle to another in a nanotube–vesicle network by using Marangoni flows. Thus, single or several species can be transferred to a neighboring vesicle at will. The technique offers new possibilities for live matter functionalization into synthetic host networks, and may provide means for studying the effect of compartmentalization and perfusion of chemical species on a single bacterium. Furthermore, it may serve as an experimental model to study how vesicle-encapsulated bacteria evade destruction in macrophages or how bacteria surf along thin membrane nanotubes toward connected macrophage cell bodies.

Johan Hurtig

Papers

Biomimetic nanoscale reactors and networks.

Intercellular nanotubes: insights from imaging studies and beyond

Imaging Immune Surveillance of Individual Natural Killer Cells Confined in Microwell Arrays

Micropipet Writing Technique for Production of Two-Dimensional Lipid Bilayer Nanotube−Vesicle Networks on Functionalized and Patterned Surfaces

Injection and transport of bacteria in nanotube–vesicle networks