Three-Dimensional Microfabrication System for Biodegradable Microdevices With High-Resolution and Bio-Applicability

2005 ◽  
Author(s):  
Akira Yamada ◽  
Fuminori Niikura ◽  
Koji Ikuta
Keyword(s):  
Tensile Strength ◽  
Biodegradable Polymers ◽  
Conventional Method ◽  
Three Dimensional ◽  
Single Layer ◽  
Batch Process ◽  
Potential Applications ◽  
A Cell ◽  
The One ◽  
Almost All

Biodegradable polymers are employed in medicine and its further application is expected with eagerness. But the lack of an appropriate processing method retards the progress. To overcome this problem, we have developped a novel three-dimensional microfabrication system. The system design allows us the processing of the free three-dimensional micro-level forms by stacking up melted polymers from the nozzle. Different from the conventional method, we adopted a batch process to supply materials in order to eliminate the prior process that required toxic solvents. In addition, it is possible to handle almost all biodegradable thermoplastic resins by adopting this system. A single layer from the piled-up layers of extruded lines was observed to evaluate the resolution. The lateral and depth resolutions attained are 40 μm and 45 μm, respectively. Biodegradable polymers enable three-dimensional microstructures such as micro-pipes, micro-bends, and micro-coil springs to be manufactured in less than 15 min. The biocompatibility of the newly fabricated structure was evaluated using a cell line (PC12). For this purpose, a small vessel, with a transparent base, was fabricated using PLA and cells were cultivated in it. The results were then compared with the results obtained using the standard method. The mechanical strength of our microstructures was evaluated using a tensile strength test. The tensile strength of the microstructure was lower than the one obtained from the conventional method, but has enough strength for fabrication of medical devices. Our system renders it possible to produce toxic-free, as well as transparent and leakage-free devices. Our system is expected to have potential applications in optimum design and fabrication of implantable devices, especially in tissue engineering.

scholarly journals Development of a tunable 3D wrinkled platfom for designing cellular three-dimensional communication networks

2021 ◽  
Author(s):  
Bethany R. Hughes
Keyword(s):  
Communication Networks ◽  
Three Dimensional ◽  
Cell Communication ◽  
Cellular Growth ◽  
Clinical Aspects ◽  
Wide Range ◽  
Cellular Communication Network ◽  
Potential Applications ◽  
A Cell ◽  
Washing Method

The study of cell-cell communication is hindered by the absence of a platform which is capable of specifically directing cellular growth while allowing examination of the communication between cells. In this thesis, a tuneable micro-to-nano scale wrinkled nonplanar platform was developed and optimized through the use of photolithography and a microfluidic washing method. The platform demonstrated the ability to create micro and nanowrinkled structures in a wide range of flow conditions. The developed platform was then used as a cell culture platform to investigate the spacing dependence of bovine fibroblasts. The identification of a critical bridging distance for bovine fibroblasts provided a means to optimized the platform for culturing a cellular communication network between bovine fibroblasts. The cellular network which resulted demonstrated, via FRAP (Fluorescence-recovery-after-photobleaching), the capacity for communication between cells. Creating multilevel length scaled structures on a tunable platform which directed cellular growth while maintaining communication presents potential applications in research, industry and clinical aspects.

Magnetic magnesium oxide composites for rapid removal of polycyclic aromatic hydrocarbons and cadmium ions from water

2020 ◽  
Vol 17 (7) ◽  
pp. 479
Author(s):  
Dongqin Tan ◽  
Jing Jin ◽  
Cuicui Guo ◽  
Dhanjai ◽  
Jiping Chen
Keyword(s):  
Polycyclic Aromatic Hydrocarbons ◽  
Aromatic Hydrocarbons ◽  
Three Dimensional ◽  
Precipitation Method ◽  
Precipitation Process ◽  
Cadmium Ions ◽  
Potential Applications ◽  
Equilibrium Data ◽  
Polycyclic Aromatic ◽  
Almost All

Environmental contextRemediation of wastewater containing polycyclic aromatic hydrocarbons and metals is essential to limit adverse effects on the environment and human health. Using a simple precipitation method, we prepared porous magnetic MgO hybrids for use as a material for removing pollutants from wastewater. The material showed excellent removal performance for 12 polycyclic aromatic hydrocarbons and cadmium ions, and thus has potential applications in wastewater treatment. AbstractHierarchical porous magnetic MgO hybrids (Fe3O4/MgO) are controllably synthesised based on a facile precipitation process. The resulting material displays a three-dimensional architecture with nest-like morphology, large surface area (135.2m2 g−1) and uniform mesochannels (5–35nm). The adsorption equilibrium data of target polycyclic aromatic hydrocarbons (PAHs) on Fe3O4/MgO sorbents are described by the Langmuir isotherm model. The composites show a strong tendency for the removal of PAHs owing to their porous structure that possesses an excellent affinity for PAHs. Under the optimal conditions, a removal of more than 70% is achieved for 12 PAHs. The materials also exhibit a good removal ability of cadmium (Cd2+) from water with fast adsorption (<5min) and high removal percentage (>80%). Moreover, the composites possess sufficient magnetism for separation. To demonstrate the performance of the sorbents, Fe3O4/MgO is exposed to aqueous samples spiked with low concentrations of PAHs and Cd2+. In almost all cases, the composites are superior to the commercially available sorbents as well as un-functionalised Fe3O4 nanoparticles. Therefore, this work provides a promising approach for the simultaneous removal of PAHs and Cd2+ from water using multifunctional MgO microspheres.

A one-dimensional zinc(II) coordination polymer with a three-dimensional supramolecular architecture incorporating 1-[(1H-benzimidazol-2-yl)methyl]-1H-tetrazole and adipate

2016 ◽  
Vol 72 (12) ◽  
pp. 1002-1006 ◽  
Author(s):  
Chun-Li Liu ◽  
Qiu-Ying Huang ◽  
Xiang-Ru Meng
Keyword(s):  
Coordination Polymer ◽  
Room Temperature ◽  
Main Chain ◽  
Three Dimensional ◽  
Coordination Geometry ◽  
Supramolecular Architecture ◽  
One Dimensional ◽  
Potential Applications ◽  
Metal Organic ◽  
The One

The synthesis of coordination polymers or metal–organic frameworks (MOFs) has attracted considerable interest owing to the interesting structures and potential applications of these compounds. It is still a challenge to predict the exact structures and compositions of the final products. A new one-dimensional coordination polymer,catena-poly[[[bis{1-[(1H-benzimidazol-2-yl)methyl]-1H-tetrazole-κN3}zinc(II)]-μ-hexane-1,6-dicarboxylato-κ4O1,O1′:O6,O6′] monohydrate], {[Zn(C6H8O4)(C9H8N6)2]·H2O}n, has been synthesized by the reaction of Zn(Ac)2(Ac is acetate) with 1-[(1H-benzimidazol-2-yl)methyl]-1H-tetrazole (bimt) and adipic acid (H2adi) at room temperature. In the polymer, each ZnIIion exhibits an irregular octahedral ZnN2O4coordination geometry and is coordinated by two N atoms from two symmetry-related bimt ligands and four O atoms from two symmetry-related dianionic adipate ligands. ZnIIions are connected by adipate ligands into a one-dimensional chain which runs parallel to thecaxis. The bimt ligands coordinate to the ZnIIions in a monodentate mode on both sides of the main chain. In the crystal, the one-dimensional chains are further connected through N—H...O hydrogen bonds, leading to a three-dimensional supramolecular architecture. In addition, the title polymer exhibits fluorescence, with emissions at 334 and 350 nm in the solid state at room temperature.

Study of thermoelastic damping in fully clamped bilayered rectangular microplate resonators based on three-dimensional heat conduction

2020 ◽  
Vol 44 (1) ◽  
pp. 10-22
Author(s):  
Xiaopeng Li ◽  
Linlin Wang ◽  
Wujiu Pan ◽  
Zemin Yang ◽  
Jinchi Xu
Keyword(s):  
Heat Conduction ◽  
Three Dimensional ◽  
Single Layer ◽  
Thermoelastic Damping ◽  
Dimensional Model ◽  
Layer Model ◽  
Three Dimensional Model ◽  
Formula Derivation ◽  
The One ◽  
Single Layer Model

Under the condition that microresonators work at room temperature or vaccum, thermoelastic damping is one of the main mechanisms of energy dissipation. Thermoelastic damping caused by the internal consumption of thermoelastic materials has always prevented the improvement of the quality of microresonators. In this paper, the theoretical model of thermoelastic damping in fully clamped bilayered plate microresonators based on the theory of three-dimensional heat conduction is first established and then verified to be equivalent to the previous single-layer model or not through the formula derivation. Analysis on thermoelastic damping at the first-order frequency where microresonators usually work is carried out afterwards. The differences of thermoelastic damping in the present three-dimensional model with different materials are investigated, including the convergence speed and the value of thermoelastic damping with different thicknesses. Then, with different lengths, widths, and thicknesses, but the same combination of materials, the thermoelastic damping is investigated in the present model. Furthermore, the present bilayered model is compared with the single-layer model to investigate their equivalent relationship. Finally, the present three-dimensional model is compared with the one-dimensional model and FEM models to investigate its feasibility.

Honeycomb Films of Biodegradable Polymers for Tissue Engineering

2002 ◽  
Vol 724 ◽  
Author(s):  
Takehiro Nishikawa ◽  
Keiko Arai ◽  
Junko Hayashi ◽  
Masahiko Hara ◽  
Masatsugu Shimomura
Keyword(s):  
Biodegradable Polymers ◽  
Three Dimensional ◽  
Single Layer ◽  
Amphiphilic Polymer ◽  
The Self ◽  
Double Layers ◽  
Tissue Formation ◽  
Moist Air ◽  
Flat Film ◽  
Microporous Films

AbstractWe report that microporous films (honeycomb films) can lead various types of cells to tissue formation. The honeycomb films were fabricated by applying a moist air to a spread polymer solution containing biodegradable polymers (poly(L-lactic acid) (PLLA) and poly (ε-caprolactone) (PCL)) and an amphiphilic polymer. Hepatocytes were cultured on a self-supporting honeycomb film of PLLA. The hepatocytes formed a single layer of columnar shape cells with a thickness of 20 μm. The tissue formation of hepatocytes specifically occurred on the honeycomb film of PLLA, not on a flat film of PLLA. Three dimensional tissue structures were formed, when cells were cultured on both sides of the self-supporting honeycomb film. Double layers of hepatocytes were obtained by the method. Striated tissues such as heart and blood vessel could be reconstructed by utilizing a stretched honeycomb film of PCL.

scholarly journals Development of a tunable 3D wrinkled platfom for designing cellular three-dimensional communication networks

2021 ◽  
Author(s):  
Bethany R. Hughes
Keyword(s):  
Communication Networks ◽  
Three Dimensional ◽  
Cell Communication ◽  
Cellular Growth ◽  
Clinical Aspects ◽  
Wide Range ◽  
Cellular Communication Network ◽  
Potential Applications ◽  
A Cell ◽  
Washing Method

The study of cell-cell communication is hindered by the absence of a platform which is capable of specifically directing cellular growth while allowing examination of the communication between cells. In this thesis, a tuneable micro-to-nano scale wrinkled nonplanar platform was developed and optimized through the use of photolithography and a microfluidic washing method. The platform demonstrated the ability to create micro and nanowrinkled structures in a wide range of flow conditions. The developed platform was then used as a cell culture platform to investigate the spacing dependence of bovine fibroblasts. The identification of a critical bridging distance for bovine fibroblasts provided a means to optimized the platform for culturing a cellular communication network between bovine fibroblasts. The cellular network which resulted demonstrated, via FRAP (Fluorescence-recovery-after-photobleaching), the capacity for communication between cells. Creating multilevel length scaled structures on a tunable platform which directed cellular growth while maintaining communication presents potential applications in research, industry and clinical aspects.

scholarly journals The structure of the wall of the green alga Valonia ventricosa

1937 ◽  
Vol 122 (826) ◽  
pp. 76-97 ◽  
Keyword(s):  
Plant Cell Wall ◽  
Three Dimensional ◽  
Chain Structure ◽  
Point Of View ◽  
Considerable Importance ◽  
Yield Information ◽  
Degree Of Certainty ◽  
A Cell ◽  
Carry Over ◽  
Almost All

Although for many years the study of cytology has tended to concentrate attention more and more on the protoplast as the fundamental unit of the plant, there can be no doubt that the membrane surrounding this unit plays a part of considerable importance in its life processes. The deposition of such a membrane, by a process which is as yet quite obscure, is obviously closely connected with protoplasmic activity, and a detailed investigation of its structure is bound to lead to a better understanding of this connexion. At the same time, the shape and size of a cell are clearly due in some degree to the action of forces external and internal on the membrane, so that a study of the structure of the plant cell wall should therefore also yield information of considerable importance in the solution of botanical problems concerned with cell elongation and growth. Comparatively recent investigations, carried out chiefly on plant fibres, have shown that the most important component of cell walls, from a structural point of view, is the polysaccharide cellulose. This substance is known to occur in varying proportions in the walls of almost all plant tissue and its structure has been worked out, chiefly by X-ray and chemical methods, with some degree of certainty. Although much remains to be discovered of the organization of cellulose in the wall, certain details are now quite clear. Celluloses obtained from many and varied plant sources have all proved to have essentially the same structure. They exist only in the form of chains of β -glucose residues, at least 500 A long (Hengstenberg and Mark 1928), bound together laterally by secondary valences to form a three-dimensional lattice. The conception of a definite micelle, in the sense of Nägeli, is no longer widely held, although the lattice is not uniformly regular throughout the wall. The chains of cellulose are more probably bound together into ill-defined bundles separated by regions in which they are not so perfectly oriented. This conception of the existence of cellulose in long molecular chains has arisen from the examination of the secondary walls of plants, but as yet no direct experimental determinations have been possible of its structure in primary walls where it is known to occur ( e. g . in Vicia faba , see TupperCarey and Priestley 1922). Recent work (Preston 1934) on the tracheids of the conifer, however, show that it is possible to carry over the idea of the long-chain structure of cellulose even to these delicate primary walls.

scholarly journals Characterization of the Modulatory Effect of Hydroxychloroquine on ACE2 Activity: New Insights in relation to COVID-19

2021 ◽  
Vol 2021 ◽  
pp. 1-5
Author(s):  
Juan E. Tichauer ◽  
Dagoberto Soto ◽  
Max Andresen
Keyword(s):  
Structural Changes ◽  
Three Dimensional ◽  
Specific Inhibitor ◽  
In Vitro System ◽  
Trial Outcomes ◽  
A Cell ◽  
The One ◽  
First Time

Chloroquine (CQ) and hydroxychloroquine (HCQ) have shown the ability to inhibit in vitro viral replications of coronaviridae viruses such as SARS-CoV and SARS-CoV-2. However, clinical trial outcomes have been disparate, suggesting that CQ and HCQ antiviral mechanisms are not fully understood. Based on three-dimensional structural similarities between HCQ and the known ACE2 specific inhibitor MLN-4760, we compared their modulation on ACE2 activity. Here we describe, for the first time, in a cell-free in vitro system that HCQ directly and dose-dependently inhibits the activity of recombinant human ACE2, with a potency similar to the MLN-4760. Further analysis suggests that HCQ binds to a noncompetitive site other than the one occupied by MLN-4760. We also determined that the viral spike glycoprotein segment that comprises the RBD segment has no effect on ACE2 activity but unexpectedly was able to partially reverse the inhibition induced by HCQ but not that by MLN-4760. In summary, here we demonstrate the direct inhibitory action of HCQ over the activity of the enzyme ACE2. Then, by determining the activity of ACE2, we reveal that the interaction with the spike protein of SARS-CoV-2 leads to structural changes that at least partially displace the interaction of the said enzyme with HCQ. These results may help to explain why the effectiveness of HCQ in clinical trials has been so variable. Additionally, this knowledge could be used for to develop techniques for the detection of SARS-CoV-2.

Characterization of a monolayer graphitic structure

1994 ◽  
Vol 52 ◽  
pp. 760-761
Author(s):  
X. Lin ◽  
X. K. Wang ◽  
V. P. Dravid ◽  
J. B. Ketterson ◽  
R. P. H. Chang
Keyword(s):  
Three Dimensional ◽  
Single Layer ◽  
Synthesis Process ◽  
Graphitic Structure ◽  
Positive Gaussian Curvature ◽  
Graphitic Sheet ◽  
Structural And Electronic Properties ◽  
New Material ◽  
Hexagonal Network

For small curvatures of a graphitic sheet, carbon atoms can maintain their preferred sp2 bonding while allowing the sheet to have various three-dimensional geometries, which may have exotic structural and electronic properties. In addition the fivefold rings will lead to a positive Gaussian curvature in the hexagonal network, and the sevenfold rings cause a negative one. By combining these sevenfold and fivefold rings with sixfold rings, it is possible to construct complicated carbon sp2 networks. Because it is much easier to introduce pentagons and heptagons into the single-layer hexagonal network than into the multilayer network, the complicated morphologies would be more common in the single-layer graphite structures. In this contribution, we report the observation and characterization of a new material of monolayer graphitic structure by electron diffraction, HREM, EELS.The synthesis process used in this study is reported early. We utilized a composite anode of graphite and copper for arc evaporation in helium.

Diffraction contrast of dislocations in icosahedral quasicrystals

1990 ◽  
Vol 48 (4) ◽  
pp. 454-455
Author(s):  
K. Urban ◽  
Z. Zhang ◽  
M. Wollgarten ◽  
D. Gratias
Keyword(s):  
Dimensional Space ◽  
Three Dimensional ◽  
Complete Characterization ◽  
Extinction Condition ◽  
Burgers Vector ◽  
Diffraction Contrast ◽  
Lattice Geometry ◽  
Reference Space ◽  
Icosahedral Quasicrystals ◽  
The One

Recently dislocations have been observed by electron microscopy in the icosahedral quasicrystalline (IQ) phase of Al65Cu20Fe15. These dislocations exhibit diffraction contrast similar to that known for dislocations in conventional crystals. The contrast becomes extinct for certain diffraction vectors g. In the following the basis of electron diffraction contrast of dislocations in the IQ phase is described. Taking account of the six-dimensional nature of the Burgers vector a “strong” and a “weak” extinction condition are found.Dislocations in quasicrystals canot be described on the basis of simple shear or insertion of a lattice plane only. In order to achieve a complete characterization of these dislocations it is advantageous to make use of the one to one correspondence of the lattice geometry in our three-dimensional space (R3) and that in the six-dimensional reference space (R6) where full periodicity is recovered . Therefore the contrast extinction condition has to be written as gpbp + gobo = 0 (1). The diffraction vector g and the Burgers vector b decompose into two vectors gp, bp and go, bo in, respectively, the physical and the orthogonal three-dimensional sub-spaces of R6.

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