Biomimetic Technology Research Articles

Sequence and Temperature Dependence of the End-to-End Collision Dynamics of Single-Stranded DNA

Intramolecular collision dynamics play an essential role in biomolecular folding and function and, increasingly, in the performance of biomimetic technologies. To date, however, the quantitative studies of dynamics of single-stranded nucleic acids have been limited. Thus motivated, here we investigate the sequence composition, chain-length, viscosity, and temperature dependencies of the end-to-end collision dynamics of single-stranded DNAs. We find that both the absolute collision rate and the temperature dependencies of these dynamics are base-composition dependent, suggesting that base stacking interactions are a significant contributor. For example, whereas the end-to-end collision dynamics of poly-thymine exhibit simple, linear Arrhenius behavior, the behavior of longer poly-adenine constructs is more complicated. Specifically, 20- and 25-adenine constructs exhibit biphasic temperature dependencies, with their temperature dependences becoming effectively indistinguishable from that of poly-thymine above 335 K for 20-adenines and 328 K for 25-adenines. The differing Arrhenius behaviors of poly-thymine and poly-adenine and the chain-length dependence of the temperature at which poly-adenine crosses over to behave like poly-thymine can be explained by a barrier friction mechanism in which, at low temperatures, the energy barrier for the local rearrangement of poly-adenine becomes the dominant contributor to its end-to-end collision dynamics.

ChemInform Abstract: Theoretical Studies and Industrial Applications of Oxidative Activation of Inert C—H Bond by Metalloporphyrin‐Based Biomimetic Catalysis

AbstractReview: 162 refs.

Letter to the Editor

Dear Editor,I would like to highlight a few key aspects of Ohno and colleagues1 excellent paper published in this issue of Journal of Oral Implantology (JOI) and thank the authors from Kanagawa Dental College for their collaboration and outstanding work. The article focuses on using OsteoGen crystals coated with a biomimetic nano-crystalline fluorapatite surface technology to promote osteoblast cell differentiation, migration, and proliferation, which are expected to accelerate bone growth; a finding supported by our own and a related researcher's histologic findings.2 The paper established increased physiologic bioactivity for bone mineralization due to the unique fluorapatite nano-crystalline surface coating. Increased levels of the osteogenic differentiation marker, alkaline phosphatase (ALP), demonstrated this physiologic bioactivity.Osteoblast cell recruitment is also true, but to a lesser degree, with the original nonfluoridated OsteoGen crystals and clusters.3–5 Ohno and colleagues'1 paper (Figure 2a, the control noncoated crystals) confirms that OsteoGen is chemotactic with ∼6 to 7 osteoblast cells in the field of microscopic view. This control is compared to the experiment (Ohno et al1, Figure 2b) having fluorapatite coated crystals showing ∼18 to 21 osteoblast cells, or an improvement of 300% to accelerate osteoblast cell recruitment and proliferation for the purpose of laying down new bone formation.I would like to thank JOI for the opportunity to clarify some misconceptions regarding the differences between nonresorbing dense filler granules classified as ceramics (eg, hydroxylapatite [HA], tri-calcium phosphate [TCP], bovine, coralline, glass, and plastics) and nonceramic synthetic bioactive resorbable HA crystals. Physicochemically ceramic grafts are distinctively different from OsteoGen grafts.OsteoGen nonceramic crystals are not sintered like ceramics. By avoiding high temperatures associated with ceramics, the material does not lose its natural state [Ca5(PO4)3(OH)] and retains physicochemical properties similar to human trabecular bone.3,4,6 Similarities exist between nonceramic OsteoGen crystals and human bone mineral as the two have the same formulation and crystallographic structure for HA, as defined by the International Center for Diffraction Data. Ceramic granules [CA10(PO4)6(OH)2], including bovine ceramics, dehydroxylate under high heat sintering and convert to oxyapatite [Ca10(PO4)6O2], losing their hydroxyl and calcium carbonate groups.7,8 Ceramic HA is not truly an HA and these ceramic granules are dissimilar to OsteoGen crystals or biological bone, as evidenced by infrared spectroscopy and X-ray diffraction.4 Nonresorbable dense and monolithic particulates are mostly removed by macrophages and giant cells through fragmentation. This could result in passage of these particles to the regional lymph nodes, lungs, and spleen for further processing, and therefore, interfering with the normal function of these organs and possibly compromise the immune system.9,10Artzi and colleagues' clinical study9 reports that “OsteoGen is physiochemically and crystallographically equivalent to human bone,” and the “three-dimensional configuration of OsteoGen (crystal clusters) provides more space between particles when compared to ceramics. These spaces facilitate cellular and tissue proliferation into the grafted material, thus enhancing osseointegration.” Reference is made to the Sinus Consensus Conference11 where Artzi et al5 clarifies that “what is important is the implant success rate over time (3 to 5 years).” Fifteen papers have reported on the safety, effectiveness, and over 5 year cumulative 98% success rate of OsteoGen.12In conclusion, as Ohno et al1 have demonstrated: nonceramic OsteoGen crystals coated with a biomimetic nano-crystalline fluorapatite surface technology promote osteoblast cell differentiation, migration, and proliferation, which is expected to accelerate bone formation. This reaffirms the work of previous investigators.2 Beyond these benefits, the microfine nano-crystalline fluorapatite coating, both loosely and firmly bound on the nonceramic OsteoGen crystal surface provides a time-release mechanism of having a bioactive barrier resulting in the creation of a bacteriostatic state. This bacteriostatic state may aid in the control and elimination of pathogens that proliferate and destroy bone. Elimination of these pathogens may in turn reduce the incidence of periodontitis and implantitis.2

Preparative scale production and functional reconstitution of a human aquaglyceroporin (AQP3) using a cell free expression system

Understanding the selectivity of aquaporin (AQP) membrane channels and exploiting their biotechnological potential will require structural and functional studies of wild type and modified proteins; however, expression systems have not previously yielded AQPs in the necessary milligrams quantities. Cell free (CF) systems have emerged in recent years as fast, efficient and versatile technologies for the production of high quality membrane proteins. Here, we establish a convenient method to synthesize large amounts of functional human aquaglyceroporin 3 protein (AQP3), an AQP of physiological relevance conducting glycerol and some small neutral solutes besides water. Milligram amounts of AQP3 were produced as a histidine-tagged protein (hAQP3-6His) in an Escherichia coli extract-based CF system in the presence of the non-ionic detergent Brij-98. The recombinant AQP3 was purified by affinity chromatography, incorporated into liposomes and evaluated functionally by stopped-flow light scattering. Correct protein folding was indicated by the high glycerol and water permeability exhibited by the hAQP3-6His proteoliposomes as compared to empty control liposomes. Functionality of hAQP3-6His was further confirmed by the strong inhibition of the glycerol and water permeability by phloretin and HgCl2, respectively, two blockers of AQP3. Fast and convenient CF production of functional AQP3 may serve as basis for further structural/functional assessment of aquaglyceroporins and help boosting the AQP-based biomimetic technologies.

Microfibril Orientation Dominates the Microelastic Properties of Human Bone Tissue at the Lamellar Length Scale

The elastic properties of bone tissue determine the biomechanical behavior of bone at the organ level. It is now widely accepted that the nanoscale structure of bone plays an important role to determine the elastic properties at the tissue level. Hence, in addition to the mineral density, the structure and organization of the mineral nanoparticles and of the collagen microfibrils appear as potential key factors governing the elasticity. Many studies exist on the role of the organization of collagen microfibril and mineral nanocrystals in strongly remodeled bone. However, there is no direct experimental proof to support the theoretical calculations. Here, we provide such evidence through a novel approach combining several high resolution imaging techniques: scanning acoustic microscopy, quantitative scanning small-Angle X-ray scattering imaging and synchrotron radiation computed microtomography. We find that the periodic modulations of elasticity across osteonal bone are essentially determined by the orientation of the mineral nanoparticles and to a lesser extent only by the particle size and density. Based on the strong correlation between the orientation of the mineral nanoparticles and the collagen molecules, we conclude that the microfibril orientation is the main determinant of the observed undulations of microelastic properties in regions of constant mineralization in osteonal lamellar bone. This multimodal approach could be applied to a much broader range of fibrous biological materials for the purpose of biomimetic technologies.

3E06 生体模倣技術による潮流発電用潤滑システム(GS14:バイオトライボロジー)

3E06 生体模倣技術による潮流発電用潤滑システム(GS14:バイオトライボロジー)

Scalable Biofabrication of Tissue Spheroids for Organ Printing

Organ printing technology or robotic additive biofabrication of 3D functional tissue and organ constructs is based on using tissue spheroids as building blocks. In order to bioprint human organs it is necessary to develop technology for scalable production of millions tissue spheroids. Ideally, these tissue spheroids must have standard size and shape suitable for bioprinting process. The scalable biofabrication of large volume of standard size tissue spheroids could be achieved only by maximal employment of robotics and automation technologies. The three main competing groups of emerging tissue spheroid biofabrication technologies include: i) modified handing drop method, 2) molded non-adhesive hydrogel technology and iii) digital microfluidic technologies. The comparative analysis of emerging scalable tissue spheroid biofabrication technologies has been performed. Our data indicates that all these technologies have potential for robotization and automation. The molded non-adhesive hydrogel technologies provide best outcome for standardization of tissue spheroid size. The microfluidics technology has strong advantage in accelerating of tissue spheroids biofabrication (theoretically, up to 10 000 droplets per second). New emerging approaches for biofabrication tissue spheroid using nanopatterned biomimetic surface and technologies for tissue spheroid encapsulation and functionalization will be also presented. The tissue spheroid biofabrication technologies are still evolving and represent hot area in biofabrication research. Moreover, these technologies are already subject of ongoing commercialization. Thus, it is safe to predict that scalable robotic tissue spheroid biofabricators must be integrated parts of organ biofabrication line.

Low Temperature Preparation and Microstructure of TiO<sub>2</sub> Nanostructured Thin Films Coated Short Glass Fibers by Biomimetic Synthesis Technology

By using organic amine as the soft template, TiO2 nanostructured thin films have been deposited on the surface of short glass fibers (SGFs) by biomimetic synthesis technology at low temperature (85°C). The properties of composite particles, including surface morphology, the phase composition of the coating layer and microstructure were characterized by SEM, XRD, XPS and Raman. The results show that the functional layers containing NH2 and OH groups can be formed through a kind of organic amine, which can induce the bio-mineralization of nano-TiO2 on the SGFs surfaces. The XRD shows that TiO2 thin films uniformly coated on SGFs surfaces were mainly anatase. The surface roughness of SGFs was remarkably increased after coating. Compared with uncoated SGFs as filler, the abrasive loss of composite coatings decreased to 47 percent of that coatings filled with uncoated SGFs, when the composite fiber powders were filled in wear-resistant coatings based on the silicone modified epoxy resins. Therefore, anti-wear property of coatings was notably enhanced.

J028025 河川流発電のための生体模倣シール(Bio-Star)のトライボロジー特性(第2報)([J028-02]人々のくらしとバイオ(2))

Renewable energy research has been promoted to slow down climate change and maintain economic growth. Streamflow is valued as a source of energy, and environmentally friendly and low-friction sealing system that employs biomimetic technologies is proposed for its utilization. A dynamo-electric generator and ancillary systems with waterproof construction are installed under water. Lip seals with a rotating shaft function to prevent the ingress of water from the outside and excellent frictional properties with various rotation speeds are required to improve the power generation efficiency with constantly changing water flow. The sealing system was successfully developed using a hydrated material (polyvinyl formal; PVF) that mimics articular cartilage in a natural synovial joint. Polyethylene glycol (PEG) dissolved in distilled water, which is a non-Newtonian fluid, was used as a lubricant. These materials have low toxicity and low environmental impact. The biomimetic sealing system exhibits excellent frictional properties with extremely low ingress of water.

114 生体関節潤滑模倣システムを搭載した河川流発電に関する研究(OS.3 環境とエネルギー2)

114 生体関節潤滑模倣システムを搭載した河川流発電に関する研究(OS.3 環境とエネルギー2)

Hierarchical Unilamellar Vesicles of Controlled Compositional Heterogeneity

Eukaryotic life contains hierarchical vesicular architectures (i.e. organelles) that are crucial for material production and trafficking, information storage and access, as well as energy production. In order to perform specific tasks, these compartments differ among each other in their membrane composition and their internal cargo and also differ from the cell membrane and the cytosol. Man-made structures that reproduce this nested architecture not only offer a deeper understanding of the functionalities and evolution of organelle-bearing eukaryotic life but also allow the engineering of novel biomimetic technologies. Here, we show the newly developed vesicle-in-water-in-oil emulsion transfer preparation technique to result in giant unilamellar vesicles internally compartmentalized by unilamellar vesicles of different membrane composition and internal cargo, i.e. hierarchical unilamellar vesicles of controlled compositional heterogeneity. The compartmentalized giant unilamellar vesicles were subsequently isolated by a separation step exploiting the heterogeneity of the membrane composition and the encapsulated cargo. Due to the controlled, efficient, and technically straightforward character of the new preparation technique, this study allows the hierarchical fabrication of compartmentalized giant unilamellar vesicles of controlled compositional heterogeneity and will ease the development of eukaryotic cell mimics that resemble their natural templates as well as the fabrication of novel multi-agent drug delivery systems for combination therapies and complex artificial microreactors.

Ancient properties of spider silks revealed by the complete gene sequence of the prey-wrapping silk protein (AcSp1).

Spider silk fibers have impressive mechanical properties and are primarily composed of highly repetitive structural proteins (termed spidroins) encoded by a single gene family. Most characterized spidroin genes are incompletely known because of their extreme size (typically >9 kb) and repetitiveness, limiting understanding of the evolutionary processes that gave rise to their unusual gene architectures. The only complete spidroin genes characterized thus far form the dragline in the Western black widow, Latrodectus hesperus. Here, we describe the first complete gene sequence encoding the aciniform spidroin AcSp1, the primary component of spider prey-wrapping fibers. L. hesperus AcSp1 contains a single enormous (∼19 kb) exon. The AcSp1 repeat sequence is exceptionally conserved between two widow species (∼94% identity) and between widows and distantly related orb-weavers (∼30% identity), consistent with a history of strong purifying selection on its amino acid sequence. Furthermore, the 16 repeats (each 371–375 amino acids long) found in black widow AcSp1 are, on average, >99% identical at the nucleotide level. A combination of stabilizing selection on amino acid sequence, selection on silent sites, and intragenic recombination likely explains the extreme homogenization of AcSp1 repeats. In addition, phylogenetic analyses of spidroin paralogs support a gene duplication event occurring concomitantly with specialization of the aciniform glands and the tubuliform glands, which synthesize egg-case silk. With repeats that are dramatically different in length and amino acid composition from dragline spidroins, our L. hesperus AcSp1 expands the knowledge base for developing silk-based biomimetic technologies.

Theoretical studies and industrial applications of oxidative activation of inert C-H bond by metalloporphyrin-based biomimetic catalysis

High costs and low catalytic efficiency of metalloporphyrins, which are an analogue of cytochrome P450 enzyme, are the bottlenecks in the industrialization of biomimetic hydrocarbon oxidation reactions. The basic principle and research technique of physical organic chemistry were applied to the process of biomimetic oxidation of hydrocarbon catalyzed by metalloporphyrins. This biomimetic technology could be adapted to bulk chemicals production by developing the new methods for efficient scale-up synthesis of metalloporphyrins, new pathways for molecular oxygen activation on an industrial scale and new approaches to elevate the catalytic efficiency of metalloporphyrins. This review mainly focuses on research carried out in our group.

Artificial Niches: Biomimetic Materials for Hematopoietic Stem Cell Culture

Hematopoietic stem cells (HSCs) are indispensable for the treatment of patients with hematological disorders such as leukemia. However, the amount of available transplantable HSCs is limited. Therefore, new approaches to multiply HSCs in the laboratory are needed. Promising biomimetic technologies for HSC expansion are currently developed. This feature article gives an insight into the significance of this approach and introduces the essential building blocks (cells, matrix, and scaffolds) of biomimetic materials. Some recent strategies are highlighted and the challenges and possible applications of such materials are discussed.

Abstract 2842: Development of a novel TrkA HTS assay using template directed self assembly (TDA)

Abstract Tropomyosin-related kinases (Trks A, B, and C) are a family of membrane-associated receptor tyrosine kinases (RTKs) activated by neurotrophins. RTKs are shown to be implicated in Alzheimer's disease, depression, pain sensation and various cancers including tumor cell growth and survival signaling. Inhibitors of Trk receptor kinases might provide targeted treatments for neurodegenerative diseases, pain and cancer. One strategy to indentify Trk isoform-specific inhibitors is to develop an assay where compound libraries can be screened in a more-native membrane associated lipid environment. Template-Directed Self Assembly (TDA) is a biomimetic technology designed to restore membrane-associated proteins to more relevant physiological conditions. This technology utilizes recombinant histidine-tagged proteins bound to the surface of nickel-chelated liposomes. Recombinant HIS-tagged proteins are engineered on the correct terminus of the protein to reflect the polarity of the enzyme with respect to the membrane. This allows the HIS-tagged proteins to bind to the liposome creating an environment much like a cellular membrane. The lipids in TDA are fully fluid within the surface of the liposome and associated proteins can rotate freely. Furthermore it promotes the formation of high-order structures such as homo- or hetro-dimers and shown to recruit accessory factors. Coupling of membrane associsted kinases to liposomes reconstitutes an environment that confers proper polarity, stereochemistry, topology and other critical properties, thereby creating a more relevant biochemical assay. To date, we have shown that several RTKs have enhanced biochemical specific activity and substrate specificity that resembles physiological conditions when coupled to TDA. The TDA approach restores TrkA activity to a more-native environment; therefore, we hypothesize that we will be able to identify compounds that are more specific and selective. To address the need of an enzyme assay near a lipid membrane environment, we successfully developed a robust TrkA assay shown to exhibit up to 20-fold increase in specific activity and a reduction in Km for ATP relative to TrkA in a conventional assay. Furthermore, TDA-associated TrkA exhibited a rapid and robust trans-activation, obviating the need for a pre-activation step. Thus, assays of TrkA coupled to TDA have the potential to identify more chemically diverse and specific inhibitors. We are currently (1) validating the TDA assay with known inhibitors (2) screening a focus library to identify novel hits (3) testing the primary hits against a small kinase selectivity panel and (4) designing and developing a TrkA specific reporter cell line to confirm the primary hits. The advantages of the TDA technology will be also discussed against other therapeutically relevant RTKs. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2842. doi:1538-7445.AM2012-2842

C225 バイオミメティックベアリングの潤滑モードと軸受温度の関係(OS-13: 生体熱工学)

An environmentally friendly and low-friction bearing for applications such as tidal power or streamflow generation is proposed using biomimetic technologies. A biomimetic bearing was successfully developed using an ultra-high molecular weight polyethylene (UHMWPE) or a hydrated material, polyvinyl formal (PVF), which mimics articular cartilage in a natural synovial joint. A non-Newtonian fluid, polyethylene glycol (PEG) dissolved in distilled water, was used as a lubricant, and the biomimetic bearing exhibited excellent frictional properties to reduce the mechanical loss.

Reconstituted Lipoprotein: A Versatile Class of Biologically-Inspired Nanostructures

One of biology's most pervasive nanostructures, the phospholipid membrane, represents an ideal scaffold for a host of nanotechnology applications. Whether engineering biomimetic technologies or designing therapies to interface with the cell, this adaptable membrane can provide the necessary molecular-level control of membrane-anchored proteins, glycopeptides, and glycolipids. If appropriately prepared, these components can replicate in vitro or influence in vivo essential living processes such as signal transduction, mass transport, and chemical or energy conversion. To satisfy these requirements, a lipid-based, synthetic nanoscale architecture with molecular-level tunability is needed. In this regard, discrete lipid particles, including reconstituted high density lipoprotein (HDL), have emerged as a versatile and elegant solution. Structurally diverse, native biological HDLs exist as discoidal lipid bilayers of 5-8 nm diameter and lipid monolayer-coated spheres 10-15 nm in diameter, all belted by a robust scaffolding protein. These supramolecular assemblies can be reconstituted using simple self-assembly methods to incorporate a broad range of amphipathic molecular constituents, natural or artificial, and provide a generic platform for stabilization and transport of amphipathic and hydrophobic elements capable of docking with targets at biological or inorganic surfaces. In conjunction with top-down or bottom-up engineering approaches, synthetic HDL can be designed, arrayed, and manipulated for a host of applications including biochemical analyses and fundamental studies of molecular structure. Also highly biocompatible, these assemblies are suitable for medical diagnostics and therapeutics. The collection of efforts reviewed here focuses on laboratory methods by which synthetic HDLs are produced, the advantages conferred by their nanoscopic dimension, and current and emerging applications.

Anti-wear properties on 20CrMnTi steel surfaces with biomimetic non-smooth units

In order to gain a sufficient wear resistance for applications, the biomimetic non-smooth units in concave were fabricated on the surfaces of 20CrMnTi steel using a biomimetic laser remelting technology. The diameter and distribution of the concaves were optimized using orthogonal experiment. The microstructures of the biomimetic non-smooth units were examined. The anti-wear behaviors were investigated by the rolling wear test with lubricant. The results of wear tests indicated that the biomimetic surfaces exhibit a higher anti-wear ability than the smooth surfaces. The biomimetic surface with concaves of 250 μm in diameter and transverse distance of 270 μm and longitudinal distance of 400 μm exhibits the best anti-wear property. The enhancement of wear resistance can be mainly attributed to the action of biomimetic non-smooth units and the super fined microstructure and hardness in the biomimetic unit zones.

Studies of hydrodynamics in fishlike swimming propulsion

In this paper, we will attempt to provide an overview on the hydrodynamics of fishlike swimming propulsion based on our recent work performed experimentally, numerically and theoretically. We mainly present some typical work, including measurement on kinematics of free-swimming fish and prediction of dynamics acting on an arbitrarily deformable body, numerical and experimental simulations of flow over flapping and traveling wavy bodies, and the relevant biomimetic technology.

Biomimetic staring infrared imaging omnidirectional detection technology

In order to realize omnidirectional real-time detection and awareness in thermal infrared (IR) region, a kind of biomimetic miniature IR imaging detection system (BMIRIDS) has been successfully developed. It is classified as a long wave IR(LWIR) system and a mid-wave IR(MWIR) one. The former consists of a LWIR fish-eye lens and a LWIR focal plane array (FPA)-biomimetic electronic module, the latter consists of a MWIR fish-eye lens and a MWIR FPA-biomimetic electronic module. Both can provide complete hemispherical staring field of view, and have the capability to determine target bearings, to remove all stationary scene clutter and only detect moving targets, to sense targets range and their velocity. The capability closely approximates the vision process performed in nature by biological sensors. Furthermore, an additional biomimetic module block has been integrated into BMIRIDS. The module block imitating the function of human vision produces the logarithmic brightness image, and enhances the target image outline by virtue of the Roberts gradient difference. The logarithmic transform permits expanding the dynamic range of optical incidence without saturating the electric circuit, and makes the image more suitable for watching. DSP and FPGA perform the aforesaid vision functions that are advantageous to detect and track targets. Therefore, BMIRIDS can perform more powerful real-time signal and image processing on the resulting image data than the ordinary previous systems mainly by the aid of “software-only” processing. Because BMIRIDS has a 2π-steradian (sr.) staring field-of-view, two of such systems opposed to one another would provide a complete view of space around the sensor platform. In addition, its low power consumption makes itself meet the manifold platforms’ needs. The practice has proved that BMIRIDS can truly realize “omnidirectional” “real-time” situation awareness and dynamic information acquirement. By virtue of biomimetic technology, some limitations of the current photoelectric equipment have been broken and a new type of IR equipment has been developed.