Microscale and nanoscale chip are adaptable to the future of microreactors and small sensors. Interactions between proteins and biomaterials surfaces correlate with many important phenomena in biological systems. In this research, we investigated the separation capability of proteins using microfluidic system, involving modified surface with poly(amidoamine) (PAMAM) dendrimer and poly(2-methacryloyloxylethyl phosphorylcholine(MPC)-co-n-butyl methacrylate(BMA)) (PMB30W). The PAMAM dendrimer and PMB30W provided a facile way to inhibit non-specific protein adsorption, and influenced flow velocities of proteins. We believe the microfluidic device with dendrimer coated surface plays important role in the development of useful materials for biomolecular separation.
The 3-dimensional hydrogel structure consisted of phospholipid polymer with electron mediator integrates the advantages of loading higher density enzyme and preventing biofouling as biosensor electrode. A layer-by-layer (LBL) building up process of redox polymer hydrogel electrode based on two water-soluble polymers is carried out in this study. Poly(2-methacryloyloxyethyl phosphorylcholine-co–n-butyl methacrylate-co-p-vinylphenylboronic acid-co-vinylferrocene) was synthesized as redox phospholipid polymer through radical polymerization. The LBL hydrogel film was formed on Au electrode pretreated with alkyl mercaptan and a photoreactive polymer, by immersing the electrode into PMBVF and poly(vinyl alcohol) aqueous solution alternately. The formation of swelling hydrophilic film was validated by atomic force microscope and contact angle measurement. The thickness of polymer layer increased linearly with the number of the LBL cycles. And cyclic voltammetry was employed to characterize the electrochemical property of the hydrogel multilayer. The characteristics were depended on the ratio of ferrocene units in the polymer, as well as the number of bilayers. The results can make developing well-defined interface for the amperometric biosensors.
Hydrophilic modification of polyethylene terephthalate (PET) was successfully demonstrated by surface wave plasma treatment followed by graft polymerization with various monomers such as acrylic acid (AA), (2-hydroxyethyl) methacrylate (HEMA), and styrene (St) in the vapor phase. The plasma treatment did not physically damage the PET surface. The graft reactions were confirmed by water contact angle measurements and X-ray photoelectron spectroscopy (XPS). The water contact angles of the PET surface modified with hydrophilic AA and HEMA monomers decreased from approximately 80° before treatment to less than 35°, and the hydrophilicity of the PET surface modified by hydrophilic AA and HEMA monomers was maintained for 70 h. 3T3 fibroblast cells were cultured on the modified PET surfaces to investigate the bioactivity of the modified PET surfaces.
Optical microdevices have attracted much attention as promising tools for advanced bioimaging and/or biosensing at the single-molecule level. Various technologies developed by the semiconductor industry are applied effectively to fabricate their microstructures. We studied fabrication process of a new single-molecule imaging device consisting of a microaperture array in a transparent perfluoropolymer film coated on a glass plate, with special attention to process-induced optical damage. Highly anisotropic etching using argon/oxygen mixed plasmas was firstly examined for engraving the aperture array, but it was found that the UV emission from the excited argon in the plasma causes optical damage to the polymer and that the degree of damage was not negligible for the purpose of using the device in single-molecule imaging. Then, an alternative process that involves thermal nanoimprinting and oxygen-plasma removal of thin residual layers was adopted to enable damage-free fabrication process of the polymeric microaperture array device for single-molecule imaging.
Poly(trimethylene carbonate) (PTMC) and polylactide (PLA) are of great interest for use in various biomedical materials. To characterizethe surface properties, we measuredtheirstatic water contact angle and the feasibility for immobilization of proteins on various surfaces. The measured contact angles indicated that a PTMC surface can be enrich in hydrophobic segments by changing the external conditions. By contrast, PLA surfacesmaintained constant surface conditions under changing external conditions. Furthermore blended PTMC-PLA showed different surface properties that were based on the properties of PTMC and PLA, and surface enrichment of hydrophobic segments was maintained. The application of this blended surface as a biointerface was studied in terms of the feasibility for protein immobilization. By maintaining enrichment in cholesterol derivatives, blending PTMC with PLA promoted protein immobilization. Hence, we conclude that surface enrichment of cholesterol derivatives can be controlled by blending PLA with PTMC.
This study reports new functionalized material for biomaterial. The polymeric micelles were studied by many researchers for addition of function. Therefore, we designed a block polymer to have hydrophilic and hydrophobic segments by hybrid polymerization. It would be expected the capacity to respond to stimulus voluntarily and autonomously. Hybrid polymerization was performed by a combination of ring opening polymerization of TMC and living radical polymerization of two types of multifunctional vinyl monomers, namely, N-isopropylacrylamide (NIPAAm) and 2-methacryloyloxyethyl phosphorylcholine (MPC). Copolymerization with NIPAAm and MPC from the macro-initiator using poly(trimethylene carbonate) was successfully achieved. The resulting polymer was characterized by structural analysis of 1H-NMR, GPC, and IR. In addition it spontaneously formed self-aggregation in water. This hybrid polymerization approach is capable of producing polymer micelles with versatile hydrophilic segment.
Poly(trimethylene carbonate) (PTMC) shows biodegradability and is currently being utilized in medical devices. In this study, poly(ethylene glycol) monomethyl ether (mPEG) was incorporated into the terminating end of a PTMC molecule. mPEG, which has a hydrophilic segment, was selected as the initiator. Two kinds of mPEG with average molecular weight 5000 g/mol and 350 g/mol was used. The resulting polymer spontaneously aggregated in the organic solvent. The aggregations were quite stable for 2 months at room temperature. The composition, the hydrophilic and hydrophobic segment, was dominant factor to regulate the stability of polymer aggregation. The time to reach complete dissociation was variable, and the stability of the polymer aggregation was more than 1 month. The difference in its stability would depend on its circulation in our body for 2 months because of the difference in its degree of polymerization and composition. Moreover, the drug loading property using the resulting aggregations was examined using Basic Blue17, which is an organic dye and is used as a model substance. We have found that the organic dye was successfully loaded into the aggregations.
We have studied the preparation of 2-methacryloyloxyethyl phosphorylcholine (MPC) polymer microcapsules as a carrier for living cells by two microfluidic methods as follows: (i) By photoinduced radical polymerization of MPC, the microcapsules with ca. 85 μm in the diameter were obtained, however, they had low mechanical strength to maintain their shape. (ii) By cross-linking of poly(MPC-co-n-butyl methacrylate-co-4-vinylphenyl boronic acid) (PMBV) and poly(vinyl alcohol) (PVA), oval-shaped capsules were obtained. Even the capsules were not spherical, the size of the capsules were uniformed. Resultant capsules had mechanical strength enough for maintaining their shape. Sedimentation of the capsules, leading to collapse and coalescence, was prevented by using silicone oil as collection medium. The capsules prepared by the cross-linking method would be suitable candidate for microsized cell carriers and cell culture vessels because the MPC polymers possess highly cytocompatibility.
Inspired by mussel adhesion mechanism, a new bioinspired polymer containing phospholipid polar groups for ultra-low biofouling was designed. The polymer (named as PMDP) was composed of both 2-methacryloyloxyethyl phosphorylcholine (MPC) unit and 3,4-dihydroxyphenyl group for surface anchoring. The PMDP coating with 20 nm in thickness could be formed on titanium (Ti) alloy substrate simply by 10s dip coating without drying process. Even when the Ti alloy substrate with PMDP coating was immersed in the aqueous medium for a week, no change in the thickness was observed, that is, the PMDP adhered very stably. Adsorption of protein occurred on the Ti alloy substrate; however, it could not be observed on the PMDP coated Ti alloy substrate. Thus, the PMDP coating was effective to suppress biofouling. It is concluded that the surface treatment process with PMDP is quite simple, quick and reliable, which has great potential for improvement of biofouling on the Ti alloy substrate as implant devices.
When medical devices are developed, technologies to control the adhesion behaviors of the cells on the material surface are important. On phase-separated nanodomain structures of amphiphilic diblock copolymers, cell adhesion behaviors are influenced by any factors (for example, surface asperity, selective adhesion of proteins to domains, viscoelasticity of domains, and chemical composition are the suspicious factors). So nanodomain structured surfaces of block copolymers are expected as a modification of surface to control the cell adhesion behaviors. In this study, block copolymer, poly(2-methacryloyloxyethyl phosphorylcholine(MPC)-b-polydimethyl siloxane(PDMS)) and random copolymer, poly(MPC-r-3-(Methacryloyloxy)propyltris (trimethylsilyloxy)silane(MPTSSi)) are synthesized to induce heterogeneous and homogeneous sufaces, respectively. On both heterogeneous and homogeneous surfaces, almost same chemical compositions and following similar amount of protein adsorption was observed. However, significantly large amount of cells wee adhered on the phase-separated nanodomain structures of amphiphilic block copolymers, whereas no adhered cells were observed on homogeneously prepared random copolymer surface. Therefore, we found that the selective adsorption of protein, that is, cell-adhesive proteins, with high density on hydrophobic domains is an important factor on cell adhesion.
For sustainable agricultural production, composting of wasted organic materials is an essential recycling method. During the composting process, turning with agricultural machinery is generally done for aeration and homogenization to stimulate microbial activity. The reduction of the non-carbon neutral CO2 from fossil combustion by farm machinery used for periodical turning must be discussed. In this study, we focused on the blending of biochar, produced by the pyrolysis of agricultural residues, with composting mixture. Recently, researchers have focused on biochar as an attractive tool for carbon sequestration. Our report suggests that the blending of biochar has a great potential for carbon offset in composting of organic waste materials. The 10% biochar-blended composting has the capacity to offset from 50% to 90% of the carbon emitted from farm machinery used during composting. Our results also showed that blending of charcoal (a kind of biochar) can suppress the emission of CH4 during composting. The porous structure of charcoal supplies an aerobic environment in which the organic materials can degrade aerobically.
For the aromatic compounds as petroleum substitute from lignin, lignophenols synthesized from native lignins through the phase-separation process were depolymerized under the mild alkaline condition. Monophenols recovered from alkaline depolymerized softwood and hardwood lignophenol having many guaiacyl aryl coumaran and syringyl aryl coumaran structures remained diphenylmethane type structure by nucleus-exchange method in good yield. And it was confirmed that the high and low molecular weight fraction of alkaline depolymerized lignophenol had the different structural features by nucleus-exchange treatment.
Through the phase separation treatment with a concentrated acid and a phenol derivative, 80 % of native lignins in rice straw got ether soluble, having high frequency of combined phenols. The successive phase separation treatments of rice straw, followed by western hemlock were carried out. In this process ether soluble fractions from native lignin in rice straw worked as external nucleophiles to native lignin in western hemlock. With increasing the mol ratio of western hemlock- to rice straw lignins, a yield, a weight-average molecular weight (Mw) and a content of methoxyl group of resulting lignin derivatives (acetone soluble, ether insoluble fractions) got higher, having lower and broad absorption at 815 cm-1 in FT-IR spectra, attributed to C-H out of planes skeletal vibration of aromatic ring despite the same contents of combined p-cresol. These results suggested the formation of hybrid types of lignins composed of rice straw- and western hemlock lignins.
To understand effect of chemical reactions of the activation process on pore structures, the activated carbon materials were fabricated by two types of chemical agent for the activation process from rice husk ashes. NaOH and Na2CO3 were used as a chemical agent. And their pore structure and hydrogen storage ability were estimated on temperature range from 77 to 298 K. The porous carbon activated by NaOH involved pores of 0.6, 1.1 and 1.5 nm diameter. The pore sizes in porous carbon activated by Na2CO3 were 0.6 and 1.5 nm in diameter. These results indicated that pore structures could be controlled by chemical agents on the activation. The hydrogen storage ability of the porous carbon material activated by NaOH was the same as that activated by Na2CO3 and the value was about 0.5 wt.% at 298 K. With a decrease in temperature, hydrogen storage ability was increased, and the difference of the maximum amount of stored hydrogen on these two porous carbon materials was made larger. The hydrogen storage ability at 77 K porous carbons activated by NaOH and Na2CO3 indicated 3.7 and that for Na2CO3 was 2.1 wt.%. From pore size distributions and temperature dependence, it was suggested that the size of pore for the hydrogen storage changed from 0.6 nm to both 0.6 and 1.1 nm with decreasing temperature.
The L10 ordering and microstructures of FePt films fabricated by gas flow sputtering using two heating methods, i.e., heating during deposition and post-annealing in vacuum, were studied. A 60-nm-thick film with an order parameter above 0.6 was obtained at a heating temperature of 300°C using both methods. While the film that is heated during sputtering consists of closely packed fibrous grains, the post-annealing method produces a film containing voids. The differences in the microstructures of the films fabricated by the two heating methods are explained by means of a structure zone model.
Tryptanthrin (T) and 13 of its derivatives (T2NH2, T2Cl, T2Br, T2NO2, T8OMe, T8Me, T8F, T8Br, T8NO2, T2NH28OMe, T2NH28NO2, T2Br8Br, and T2NO28NO2) were synthesized, and their antimicrobial activities against a gram-positive bacterium (methicillin-resistant Staphylococcus aureus, MRSA) and a fungus (Malassezia furfur) were investigated. The antibacterial and antifungal activities were influenced by the substituents on tryptanthrin, with halogen-substituted tryptanthrin derivatives (T2Cl, T2Br, T8F, T8Br, and T2Br8Br) showing the highest potency against MRSA and M. furfur.
The heated dolomite powder slurry was investigated for the sporicidal activity against Bacillus subtilis spore. B. subtilis spore used in this study did not decreased at pH 1 or 13 for 2 h, indicating that the spores had a sufficient resistance. However, the dolomite powder heated at 1000℃ for 1 h could kill B. subtilis spore, even the pH of the slurry was 12.7. The dolomite powder heated at 700-750℃ did not exhibit the sporicidal activity. The sporicidal activity appeared when the dolomite powder heated at 800℃ or higher, and the raise in the heating temperature increased with the sporicidal activity. This temperature corresponded to that of generation of CaO. On the other hand, MgO did not contribute to the sporicidal activity of the heated dolomite powder. To elucidate the sporicidal mechanism of the heated dolomite powder against Bacillus subtilis spore, the generation of active oxygen from the slurry was examined by a chemiluminescence analysis. The luminescence intensity has increased when the slurry concentration rose. The results suggested that active oxygen species generated from the heated dolomite powder were associated with the sporicidal activity.
Preparation condition of SrS:Cu thin film electroluminescent (EL) elements was investigated to improve blue-EL- emission properties. The sintering temperature and time were fixed at 600℃ and 1ｈ, respectively. The Cu2S concentration of 0.3 mol% was used. The effect of step-annealing on the crystallinity of EL elements was investigated. It was found that the best crystallinity was obtained under the maximum temperature of 750℃ and annealing time of 45 or 60 min at 600℃.
BaTiO3 (BTO) nano-particles with the diameter of 15 nm were prepared by mechanical milling using planetary ball mill from the commercial BTO. Rotation speeds were selected as 0, 100, 150, 200, 250 and 300 rpm. Magnetization measurements were performed by Quantum design’s SQUID magnetometer. The 200～250 rpm samples showed the maximal saturation magnetization Ms. The 300 rpm sample showed less Ms than those of 200～250 rpm samples. The Ms of 200 rpm sample is tenth larger than the result by previous studies.
We study mono-hydrogen and hydrogen-vacancy pair in graphene by using first-principles calculations. In the most stable structure of mono-hydrogen, the hydrogen atom is bonded to one of the carbon atoms in the graphene sheet. The energy of the most stable spin-polarized state is 80 meV lower than that of the nonmagnetic state. We also study the hydrogen mono-vacancy pair. The dissociation energy of this pair into mono-vacancy and mono-hydrogen in graphene is positive (3.0eV). Therefore, when hydrogen diffuses, this complex is expected to be formed and this pair is nonmagnetic.