Until now, accomplishment of amoebic nanotubes has been actual difficult technically, because a ample bulk of baptize bread-and-butter has been bare for the amalgam of self-assembled amoebic nanotubes from amphiphilic molecules.
We accept developed a acceptable mass-synthesis adjustment for nanotubes which uses beneath than one thousandth of the bread-and-butter acclimated in accepted methods, and the time appropriate for the dehydration action is alone a few hours.
Since the nanotubes we accept developed accredit the encapsulation of anatomic substances (proteins, metal nanoparticles, etc.) beyond than 10 nm, which accept been absurd to abbreviate until now, applications to the apathetic absolution of medicines and bloom foods are expected.
Synopsis
The High Axial-Ratio Nanostructure Fabrication Team of the Nanoarchitectonics Analysis Centermost (Toshimi Shimizu, Director) of the National Institute of Avant-garde Automated Science and Technology (AIST; Hiroyuki Yoshikawa, President) accept anew advised and actinic amphiphilic molecules with hydrophilic and berserk moieties, and accept developed a address for the amalgam of assorted amoebic nanotubes of 40-200 nm in close diameter, 70-500 nm in alien diameter, and several µm in breadth by self-assembling them in amoebic solvents. This adjustment needs beneath than one thousandth of the bread-and-butter acclimated by accepted methods, enabling accomplishment of amoebic nanotubes (Figure 1). Unlike carbon nanotubes, amoebic nanotubes accept accomplished dispersibility in water, and can absorb bedfellow substances of over 10 nm in size, such as proteins and nucleic acids. The amoebic nanotubes can abbreviate alike anatomic substances that are so ample that cyclodex trins, produced on a bartering base as encapsulation substances at present, cannot do. Appropriately the amoebic nanotubes are able for appliance to assorted fields such as medical, health, and nanobio technologies.
This analysis assignment was displayed in Orgatechno 2006 captivated at Pacifico Yokohama from July 25-27.
Figure 1. (Left) White solid powders (weight = 100 g) consisting of amoebic nanotubes (mean alien bore = 80 nm, and beggarly close bore = 60 nm), and (right) a scanning electron micrograph of the nanotubes we accept developed.
Background and History of Analysis Work
Studies on carbon nanotubes, which abide of alone carbon atoms, accept been abundantly avant-garde from the appearance credibility of appliance research, activated use, and accumulation production. On the added hand, there accept been amoebic nanotubes whose alien diameters are agnate to multiple-layered carbon nanotubes of ten to several tens of nm in alien diameter. Agnate to soap molecules, the amoebic nanotubes are alveolate annular nanostructures formed by ad-lib accumulating of amphiphilic molecules with a water-soluble (hydrophilic) and oil-soluble (hydrophobic) moieties. This accumulating is alleged "self-assembly." It has been begin that alone a bound affectionate of amphiphilic molecules, such as phospholipids, glycolipids, and peptidelipids, can self-assemble into nanotube structures.
The sizes of amoebic nanotubes are usually 10-200 nm in close diameter, 40-1000 nm in alien diameter, and several to several hundreds µm in length, although depending on the amphiphilic molecules used. The molecules anatomy annular bilayer structures, in which the hydrophilic groups of the molecules are aggressive to both surfaces of anniversary bilayer to acquaintance with baptize (Figure 2). Over several millions molecules are alike abiding by absolutely intermolecular interactions after actinic bonding to anatomy abiding nanostructure structures.
Figure 2. An analogy of archetypal atomic packing of an amoebic nanotube.
The arch of anniversary tadpole-like amphiphilic atom indicates the hydrophilic accumulation and the appendage indicates the berserk group.
There accept been self-assembly methods in baptize for the amalgam of amoebic nanotubes, but the methods accept the disadvantage that a ample bulk of water, agnate to 1000-10000 times the weight of the amoebic nanotubes, is needed. Furthermore, the methods crave abounding achieve and a continued time to assuredly transform into nanotube structures (Figure 3). Thus, until now, it has been advised that the accomplishment of over 1 gram of nanotubes is difficult at the class level.
AIST has avant-garde the abstraction of the design, synthesis, and self-assembly of amphiphilic molecules for nanotube accumulation over the aftermost decade, and in this assignment we accept succeeded in the accomplishment of amoebic nanotubes. This assignment was agitated out as allotment of the Core Analysis for Evolutional Science and Technology (CREST) project, the collective analysis of the Japan Science and Technology Agency (JST) and AIST (in the FY of 2000-2005), and in the allotment of the Solution Aggressive Analysis for Science and Technology (SORST) project, the arrangement analysis of JST (in the FY of 2005-2007).
Figure 3. A morphological transformation apparatus of amphiphilic atomic assemblies, aboriginal basic all-around assemblies, again activity through circling assemblies, and assuredly consistent in nanotube-like structures in water.
Details of Analysis Work
In this work, application the hydrophilic and berserk genitalia of bargain and safe abstracts such as saccharides and peptides which can be acclimated as foods, we accept advised and actinic N-glycoside-type glycolipids and peptidelipids for the accumulation of nanotubes. Moreover, we accept succeeded in the amalgam of alveolate fiber-like amoebic nanotubes by self-assembly of the lipids in safe amoebic solvents, such as booze which is additionally acclimated for food, but not application a baptize solvent.
Figure 4. A accessible schematic diagram assuming a self-assembly apparatus of our amphiphilic molecules in an amoebic bread-and-butter (drawn by the Analysis Institute of Nanotechnology).
By acceptable processing, such as room-temperature canning and dehydration of solvents, and application amoebic solvents which are acceptable solvents of nanotube materials, we accept succeeded in mass-producing over 1 kg of solid-powdery amoebic nanotubes with the amounts of solvents lower than 1,000-10,000th of that bare for accepted methods.
Figure 4 illustrates that the actinic amphiphilic molecules can anatomy nanotube assemblies in alone one step, after ability assorted achieve like nanotubes in water, consistent in the assembly of a ample bulk of nanotubes in a actual abbreviate time. We accept accepted that the white solid powders abide of amoebic nanotubes of 40-200 nm in close diameter, 70-500 nm in alien diameter, and several µm in breadth application manual and scanning electron microscopes (Figure 5).
In this work, we accept produced over 1 kg of nanotubes application amoebic solvents of about 10 L (conventional methods charge 20,000 L of water). Furthermore, in alertness of nanotubes enabling encapsulation of anatomic substances, accepted methods charge a vacuum-drying action over several days, but our amoebic bread-and-butter adjustment makes the dehydration action accessible to achieve in several hours.
Figure 5. A scanning electron diminutive angel (transmission mode) of white amoebic nanotubes in the solid arenaceous state.
The characteristics, sizes, and functions of our amoebic nanotubes are altered from those of carbon nanotubes, and afterlife their applications, analysis and development, and analysis for activated use will be accelerated as a assignment basic from Japan. We accept appropriately alleged our nanotubes the "Organic Nanotube AIST," and we accept afresh activated for this to be registered as our trademark.
Cyclic molecules, alleged "cyclodextrin," which are constituted of 6-8 glucose molecules affiliated circularly, accept been broadly acclimated in a array of fields, such as food, medicine, and abode authority goods. Encapsulating assorted amoebic low-molecular-weight compounds in their berserk pockets, the molecules accept functions in authoritative ambiguous substances stable, in the apathetic absolution of medicines and balm chemicals, and in authoritative water-insoluble substances soluble.
On the added hand, amoebic nanotubes formed by self-assembly of glycolipids can be able-bodied broadcast in water. Furthermore, the nanotubes can abbreviate 10-50-nm calibration substances, e.g. proteins, nucleic acids, viruses, and metal nanoparticles, which cyclodextrin molecules cannot, to banish them in water. Actually, application amoebic nanotubes of 30-60 nm in close diameter, we accept succeeded in the encapsulation of metal nanoparticles of 1-20 nm in bore and all-around proteins of 12 nm in bore (ferritin) as apparent in Figure 6.
Recently articles utilizing encapsulation functions of cyclodextrin accept been researched and developed, and abounding of them accept already been produced on a bartering basis. However, our nanotubes, enabling accomplishment and encapsulation of ample molecules, are able for automated applications as new abstracts with encapsulation functions.
Figure 6. (Left and center) Manual electron micrographs of nanotubes with close diameters of 30-50 nm, encapsulating gold nanoparticles with altered sizes, respectively. (Right) a manual electron micrograph of a nanotube with an close bore of 60 nm, encapsulating ferritin with an alien bore of 12 nm.
Future Plans For Analysis Work
Hereafter, we plan to beforehand the development of amoebic nanotubes from the appearance point of new nanotube containers or new amoebic nanotube carriers with the adequacy of adsorption, encapsulation, and apathetic release, because applications to fields of (1) agronomics (the abatement of prions, slow-release manure, etc.), (2) foods (discharge of fat, anatomic fibers, etc.), (3) bloom (prevention of alopecia, allergen filters, etc), (4) medical affliction (drug commitment systems for ambition regions, hemocatharsis, capturing of viruses, administering of insulin, atomization, etc), (5) ambiance (removal of brownish particulates, etc), and (6) bloom aliment accretion abstracts for women and the elderly.
What does the chat "organic" adjure up for you in your mind? For me, ten years ago afore I began to analysis food, "organic" meant over-priced, blemished fruits and veggies. I absolutely didn't accept why anyone would pay added for what I anticipation charge be subpar produce. Of course, I had never apparent an amoebic angel at that time – I aloof believed they would be abounding of worms, back no pesticides were used. Later, afterwards I'd absolutely gone into a abundance that awash amoebic produce, and begin my aboriginal amoebic angel to not alone be birthmark free, but additionally to be the tastiest angel I had anytime had in my life, the chat "organic" took on a new acceptation for me . Now it meant tastier food, and it additionally took on the pastoral acceptation of the acceptable ancestors farm - the blazon of alloyed acreage we apprehend about in our first-grade readers.
As the advance for bistro bounded and amoebic becomes added prominent, those who abstraction and advise agronomics in academy apprenticeship accept been affected to accumulate up with society's amoebic aliment bang and behavior on non-genetically adapted (GMO) labeled products.
