Biocompatibility of zwitterionic polymer-modified surface under acidic condition

In this study, properties such as hydrophilicity and biocompatibility of surfaces prepared with 2-methacryloyloxyethyl phosphorylcholine (MPC) were evaluated under neutral to acidic conditions. The MPC-modified surface exhibit high hydrophilicity in neutral condition due to the ionization effect, while under acidic conditions below pH 3, the hydrophilicity gradually decreased due to the decrease in the negative charge of the PC groups. Biocompatibility property was evaluated by measuring the adsorption prevention effect against fibrinogen. The adsorption of fibrinogen was hardly observed on scanning electronic microscope (SEM) pictures under pH 7.6, which was significantly lower than that of the bare glass. However, the adsorption ratio increased under acidic conditions of pH 2.8 indicating a decrease in biocompatibility.


Removal of phosphate from aqueous solution by using thermally modified clamshell


Syntheses of D-glucamine and N-methyl-D-glucamine modified chitosan for boron adsorption


Temperature- and Pressure-Induced Bilayer Phase Transitions of an Amide-Linked Phosphatidylcholine: A Contrasting Effect of Chain Linkage Type

An unnatural phospholipid with two amide linkages, dipalmitoylamidodeoxyphosphatidylcholine (DPADPC), was synthesized and its bilayer phase transitions were observed by differential scanning calorimetry under atmospheric pressure and light-transmittance measurements under high pressure. The DPADPC bilayer membrane showed different phase transitions depending on the thermal history of the lipid sample under atmospheric pressure. The thermal-history dependent transitions were also observed under high pressure. The temperature pressure phase diagram and thermodynamic quantities of the phase transitions of the DPADPC bilayer membrane were compared with those of bilayer membranes of hydrophobic chain-linkage isomers, ester-liked dipalmitoylphosphatidylcholine (DPPC) and ether-linked dihexadecylphosphatidylcholine (DHPC). The thermodynamic quantities of the main transition for these PC bilayer membranes were similar to each other, whereas the suppression of the interdigitation and great stabilization of the hydrated crystal phase were observed for the DPADPC bilayer membrane. Furthermore, the results of nuclear magnetic resonance measurements indicated that the motility of PC molecules in both gel and liquid crystal phases of the DPADPC bilayer membranes were much lower than those of the DPPC and DHPC bilayer membranes. From the above results, we concluded that the molecular interaction in the PC bilayer membranes increases in the order of ether-, ester- and amide-linkage isomers.

Bulletin of the Chemical Society of Japan


Fibrinogen and albumin adsorption profiles on Ni-free Zr-based thin film metallic glass

In this study, we assessed the fibrinogen and albumin adsorption performance of Ni-free Zr-based (Zr53Cu33Al9Ta5) thin-film metallic glass (TFMG). Quartz crystal microbalance (QCM) system and fluorescence spectrophotometer were used to obtain protein adsorption measurements, using two different substrates (QCM and glass). Test samples were fabricated by coating both of the substrates with TFMG and Ti (widely used in implants) for comparison. In dynamic QCM as well as static fluorescence spectrophotometer tests, the TFMG achieved a lower fibrinogen to albumin adsorption ratio. The TFMG coating also exhibited high hydrophobicity (water contact angle of 96°) with low surface roughness of 1.06 nm and surface free energy of 35.3 mN/m. This is a clear demonstration of the excellent hemocompatibility of Ni-free Zr-based TFMG.


Enhanced activity of selenocyanate-containing transition metal chalcogenides supported by nitrogen-doped carbon materials for the oxygen reduction reaction

Selenocyanate-containing transition metal chalcogenides supported by nitrogen-doped carbon materials, denoted as CoSe/CN, demonstrate an excellent oxygen reduction reaction (ORR) ability with an electron-transfer number of 3.994, which is approximately equal to the ideal electron-transfer number 4.0. In an electrochemical measurement, CoSe/CN demonstrates excellent durability after 30 000 cycles. When an anion (alkaline) exchange membrane fuel cell uses CoSe/CN as the cathode catalyst, it shows high performance using a Fumapem FAA-3 membrane. The high catalytic performance of CoSe/CN is due to two reasons: 1) the presence of selenocyanate (SeCN-) bonding in CoSe/CN that promotes electron transfer and 2) the presence of the Co N structure that acts as the active site for the ORR. These characteristics of CoSe/CN enhance the performance of the active sites and increase the kinetic reaction rate during the ORR, thus making CoSe/CN a promising catalyst.


Observation of the interaction between avidin and iminobiotin using a graphene FET on a SiC substrate


Suppression of protein adsorption on a graphene surface by phosphorylcholine functionalization


Syntheses and properties of copper hydroxide nanosheets and controlled deposition

In this study, we synthesized copper hydroxide nanosheet and investigated its electro-chemical property and how to deposit it with a uniform amount. The precursor of the nanosheet was a layered copper hydroxide synthesized by the ion exchange of dodecyl-benzene sulfonate (DBS) with acetate in Cu2(OH)3(CH3COO)·H2O. The nanosheet was prepared by delamination of the layered copper hydroxide by dispersion in 1-butanol. Atomic force microscopy (AFM) images of the nanosheets showed lateral dimensions of ca. 2 μm with the height of ca. 4.5 nm. Cyclic voltammogram of the nanosheet in basic solution showed two cathodic peaks and two anodic peaks similar to the copper oxide electrode. To deposit the nanosheet, a quartz glass slide was dipped in the dispersion of the nanosheet in 1-butanol and dried after washing. This procedure was repeated and the ultraviolet (UV) and visible (Vis) light absorption spectrum of the slide was measured. The absorbance of the slide increased in direct proportion to the number of times of the dip-and-dry procedure. Thus, we confirmed that a controlled amount of nanosheet was deposited on the quartz glass.

International Journal of Modern Physics B


Purification of groundwater contaminated with iron and manganese by effective cost filter materials for households in rural areas

This research investigated the feasibility of effective cost filter materials for groundwater purification in the small and medium scale households in Vietnamese rural areas. The trial models could treat 30 L of groundwater with aeration flow 5 L/min for 15 min. After 24 h of sedimentation, the water was filtered through layers of gravel (h = 11 cm), sea sand (h = 11 cm), activated carbon (h = 15 cm), manganese sand (h = 12 cm), sea sand (h = 11 cm) and gravel (h = 11 cm). After treatment process, the concentration of Fe and Mn ions of the output trial models was lower than the Vietnamese standard for drinking water. The model has a simple structure and easy assembly for washing the filter materials which continued to be used for the next filtration process. These models provide in rural areas, where it promising solutions for supplying drinking water to households is difficult to get clean ground water.


Eco-friendly removal of phosphate from aqueous solution using natural dietary fibers and minerals

In this study, we focused on the investigation of phosphate removal using calcium oxide (CaO) and calcium hydroxide (Ca(OH)2) which are mainly from the calcined shells as adsorbents. Hydroxylapatite Ca10(PO4)6(OH)2, the component of industrial fertilizer was formed after the adsorption process following the XRD results. The phosphate removal increased from 20% to 97% with the aid of the mixture of flocculants alginic acid (AA), NaHCO3 and CaCl2 · 2H2O in the case of 50 ppm phosphate concentration when the samples were filtered through 2.7 μm particle retention filter paper which is roughly equivalent to the case of phosphate removal rate of 0.2 μm membrane filter paper without flocculants (99%). The results suggest that AA, NaHCO3 and CaCl2 · 2H2O as the flocculants are effective for phosphate removal from 20 to 100 ppm.


Electrochemical Oxidation of Glucose Using Copper Hydroxide Nanosheets

In this study, we synthesized copper hydroxide nanosheet and investigated electrochemical oxidation of glucose using the copper hydroxide nanosheets. The precursor of the nanosheet was a layered copper hydroxide synthesized by the ion exchange of dodecylbenzene sulfonate with acetate in Cu2(OH)3(CH3COO)·H2O. Delamination of the layered copper hydroxide prepared the nanosheet by dispersion in 1-butanol. Atomic force microscopy images of the nanosheets showed lateral dimensions of ca. 2 μm with a height of ca. 4.5 nm. Cyclic voltammogram of the nanosheet coated electrode showed oxidation current peak depend on the concentration of glucose at around +0.6 V vs. Ag/AgCl. Amperometry was measured at +0.6V vs. Ag/AgCl with successive addition of glucose solution. Glucose concentration and catalytic current were almost proportional. When the linear range is 0.1 to 4.9 mM, the sensitivity was 1.16 mA mM-1cm-2 from the slope.


EDTA-modified PANI/SWNTs nanocomposite for differential pulse voltammetry based determination of Cu(II) ions

Differential pulse voltammetry (DPV) based electrochemical sensor dedicated for the determination ofCu(II) ion concentration is reported in this research. Sensor was based on electrochemically synthesizedpolyaniline (PANI) and single walled carbon nanotubes (SWNTs) nanocomposite (PANI/SWNTs),which was additionally functionalizedby ethylenediaminetetraacetic acid(EDTA)inorder to get structure(EDTA-PANI/SWNTs) with advanced selectivity towards Cu(II) ion. Synthesis of PANI/SWNTs nanocompositewas performed by potential cycling, dodecyl benzene sulphonic acid sodium salt (DBSA) was usedas a surfactant during the synthesis of PANI/SWNTs nanocomposite to get a uniform suspension of SWNTsat room temperature. In the next step, PANI/SWNTs nanocomposite was further modified by the EDTAsolution containing 1-ethyl-3(3-(dimethylamino)propyl)-carbodiimide (EDC) as activating agent, whichis activating carboxyl groups, utilizing dip coating technique at room temperature. Differential pulsevoltammetry (DPV) technique was applied for the electrochemical detection of Cu(II) ion. DPV basedresponse of EDTA-PANI/SWNTs structure towards Cu(II) ion was investigated. Analytical signals revealthat EDTA-PANI/SWNTs structure is suitable for selective determination of Cu(II) ion in the presence ofinterfering Pb(II), Cd(II), Ni(II) and Co(II) ions


Removal of Nickel from Plating Wastewater Using the Magnetic Flocculant PG-M

In this study, a new kind of magnetic particle functionalized biopolymer (PG-M) was applied to remove nickel from plating wastewater. The key parameters of pH, adsorption time, the mass of adsorbent, and shaking speed were investigated to optimize conditions. Batch experiments were conducted with actual samples collected from a manufacturer having an initial nickel concentration of 143.73 mg/L at pH 5. The highest removal efficiency of Ni2+ ions was greater than 99% when 1 g/L of the PG-M material was added to the solution (pH=10) and stirred at 200 rpm for 20 min. The desorption of this adsorbent was performed in a 0.1 M solution of HCl and the removal efficiency of Ni2+ ions unchanged after nine cycles. The Ni2+-loaded PG-M magnetic flocculant was easily separated from the solution by an external magnet.


EDA modified PANI/SWNTs nanocomposite for determination of Ni(II) metal ions

Colloids and Surfaces A:Physicochemical and Engineering Aspects


Influence of Oxygen Ions Irradiation on Polyaniline/ Single Walled Carbon Nanotubes Nanocomposite


A fine pointed glucose oxidase immobilized electrode for low-invasive amperometric glucose monitoring

A low invasive type glucose sensor, which has a sensing region at the tip of a fine pointed electrode, was developed for continuous glucose monitoring. Platinum-iridium alloy electrode with a surface area of 0.045 mm2 was settled at the middle of pointed PEEK (Polyetheretherketone) tubing and was employed as sensing electrode. Electrodeposition of glucose oxidase in the presence of surfactant, Triton X-100, was performed for high-density enzyme immobilization followed by the electropolymerization of o-phenylenediamine for the formation of functional entrapping and permselective polymer membrane. Ag/AgCl film was coated on the surface of PEEK tubing as reference electrode. Amperometric responses of the prepared sensors to glucose were measured at a potential of 0.60 V (vs. Ag/AgCl). The prepared electrode showed the sensitivity of 2.55 mA/cm2 mM with high linearity of 0.9986, within the glucose concentration range up to 21 mM. The detection limit (S/N=3) was determined to be 0.11 mM. The glucose sensor properties were evaluated in phosphate buffer solution and in vivo monitoring by the implantation of the sensors in rabbit, while conventional needle type sensors as a reference were used. The results showed that change in output current of the proposed sensor fluctuated similar with one in output current of the conventional needle type sensors, which was also in similar accordance with actual blood sugar level measured by commercially glucose meter. One-point calibration method was used to calibrate the sensor output current.


Fabrication of hydrophilic graphene film by molecular functionalization

Physica Status Solidi (B) Basic Solid State Physics : PSS


Non-stick syringe needles: Beneficial effects of thin film metallic glass coating

This paper reports on the use of Zr-based (Zr53Cu33Al9Ta5) thin film metallic glass (TFMG) for the coating of syringe needles and compares the results with those obtained using titanium nitride and pure titanium coatings. TFMG coatings were shown to reduce insertion forces by ∼66% and retraction forces by ∼72%, when tested using polyurethane rubber block. The benefits of TFMG-coated needles were also observed when tested using muscle tissue from pigs. In nano-scratch tests, the TFMG coatings achieved a coefficient of friction (COF) of just ∼0.05, which is about one order of magnitude lower than those of other coatings. Finite-element modeling also indicates a significant reduction in injection and retraction forces. The COF can be attributed to the absence of grain boundaries in the TFMG coating as well as a smooth surface morphology and low surface free energy.


Fabrication of Low-Invasive Patch Glucose Sensors

A fine tube type glucose sensor, which has a sensing region at the inside wall of fine tube tip, was prepared and applied for a minimally invasive glucose monitoring. The enzyme glucose oxidase was immobilized on the platinum surface located in the tube by the combination of electrodeposition and electro-polymerization of o-phenylenediamine. Amperometric responses of the prepared electrodes to glucose were measured at a potential of 0.60 V (vs Ag/AgCl). The tube type electrode showed good response with good linear relationship up to the glucose concentration of 22.4 M, which was actually higher than normal sensor without outer film for permeability restriction. This may due to its unique sensor structure.


Fabrication of Amperometric Glucose Sensor Using Glucose Oxidase-Cellulose Nanofiber Aqueous Solution

Cellulose nanofiber aqueous solution, which remained virtually transparent for more than one week, was prepared by using the clear upper layer of diluted cellulose nanofiber solution produced by wet jet milling. Glucose oxidase (GOx) was easily dissolved in this solution and GOx-immobilized electrode was easily fabricated by simple repetitious drops of GOx-cellulose solution on the surface on platinum-iridium electrode. Glucose sensor properties of the obtained electrodes were examined in phosphate buffer solution of pH 7.4 at 40 C. The obtained electrode provided glucose sensor response with significantly high response speed and good linear relationship between glucose concentration and response current. After an initial decrease of response sensitivity for few days, relatively constant sensitivity was obtained for about 20 days. Nevertheless, the influence of electroactive compounds such as ascorbic acid, uric acid and acetoaminophen were not negletable.


The hydrophobic effect on electrodeposition of billirubin oxidase CotA


Preparation of micro-biosensor for continuous glucose monitoring


Effect of surface treatments on the mechanical properties of natural fiber textile composites made by VaRTM method


In Vivo Evaluation of Fine Needle Amperometric Glucose Sensors Implanted in Rabbit's Blood Vessel

Fine needle amperometric glucose sensors having outer membrane of heparin in addition of polyurethane/polydimethylsiloxane film were prepared and their glucose sensor properties were evaluated in phosphate buffer solution and in vivo monitoring by the implantation of the sensor in veins of rabbit ears. The sensitivity of the sensor was 2.2 μA mM-1 cm-2 and the detection limit for glucose was 77 μM (based on S/N = 3). Glucose sensors without heparin membrane showed glucose response on the day of implantation in vein, while reliable response was not obtained on the second day. On the other hand, the sensor with heparin outer membrane provided clear glucose response also after two days of implantation. This result indicated that the introduction of heparin membrane increased the biocompatibility of the sensor and improved the stability of sensor in vein.


Fabrication of Minimally-Invasive Patch Type Glucose Sensors


Magnetic Removal of Cesium Ions Using γ-Poly(glutamic acid)-Coated Magnetite Particles with the Enhanced Effect of Zeolite Supplementation

Magnetic removal of cesium ions (Cs) by γ-poly(glutamic acid)-coated magnetite particles (PGA-MPs) was investigated using a variety of waters. Cs was sufficiently removed from fresh water in a pH range from 7.0 to 9.0, with a removal efficiency of higher than 80% by using 5 wt % PGA-MPs, while that from artificial seawater was limited to 30%. Zeolite particles were employed as a supplementary adsorbent to adsorb Cs before the collection of zeolite with PGA-MPs. The addition of 1 wt % zeolite particles enhanced the recovery of Cs up to 97.7 ± 0.2% for fresh water and the amount of PGA-MPs required for the treatment was reduced to 0.2 wt %. Nevertheless, such improvement was not observed for artificial seawater treatment. The zeolite supplementation method performed sufficiently on the recovery of Cs in tap water and spring water, and their recoveries were both higher than 93% with R.S.D. of less than 1%. These results strongly suggest that the provided procedure can be practically applied to the removal of Cs from various inland waters.

Bulletin of the Chemical Society of Japan


Preparation of Fine Implantable Needle Type Biosensors for Blood Vessel Glucose Monitoring

Fine needle type glucose sensors with variety of outer membrane were prepared and their glucose sensor properties were evaluated by in vitro measurement in phosphate buffer solution and horse serum, and in vivo measurement using the veins of rats and rabbits. Extra-outer membrane materials of polyglutamic acid (PGA) and heparin, which provide hydrophilic surface were introduced in addition to polyurethane/polydimethylsiloxane composite outer membrane. Glucose sensors without extra-outer film and with PGA extra-outer film showed glucose response on the day of implantation, while clear response was not obtained on the second day of implantation due to the adsorption of thrombus on the sensor surface. On the other hand, the sensor with heparin outer membrane provided satisfactory glucose response also on the second day.


Preparation of an electrode modified with a thermostable enzyme Bacillus Subtilis CotA by electrodeposition

International Journal of Modern Physics: Conference Series


Study of Mutielemental Adsorption on Activateed Carbon


Flow immunosensing system utilizing antibodies immobilized on beads coated with poly-2-[3-(methacryloyl-amino)propylammonio]ethyl 3-aminopropyl phosphate


Study of the Removal of Pb2+ from Aqueous Solution by Poly-γ-glutamic Acid Coated Magnetic Nanoparticles

In this study, a novel low cost magnetic adsorbent material prepared by poly-gamma-glutamic acid (gamma-PGA) coating Fe3o4 magnetic particles, which was called coated magnetic namoparticles (PG-M) was developed for the removal of Pb2+ from water by Dr. Yasuzawa. The particle size of PG-M was about 120-320 nm, and there was no significant difference in Fe3O4 and PG-M particle size, Fe3O4 was only as the support of PG-M core and did not directly involve in the reaction. The shape of PG-M was irregular cubic structure. The experiments were applied to quantify adsorptive time, pH, competitive ion and organics on the removal effect of Pb2+. The results showed that PG-M was effective in removal of Pb2+; the equilibrium amount of adsorptive was as high as 93.3 mg/g and the optimized condition of pH value for metal ions removal was 7.0, while contact time was about 45 min. The removal efficiency of Pb2+ was not significantly influenced by Na+ while was reduced with the increasing concentration of Ca2+. The removal of Pb2+ was enhanced with the presence of organic matter (humic acid, HA) when the concentration of HA was below 5 mg/L, and decreased when the concentration of HA exceeded 5 mg/L. Langmuir isotherms fitted the experimental data better compared to Freundlich isotherms. Pseudo second order model well described the sorption kinetics of Pb2+. The used PG-M can be desorbed by 0.1 mol/L HCl and became reusable. PG-M is nontoxic and eco-friendly, which have a good prospect in water treatment.


Improvement of accuracy in flow immunosensor system by introduction of poly-2-[3-(methacryloylamino)propylammonio]ethyl 3-aminopropyl phosphate


Highly Selective Needle-Type Glucose Sensors Prepared by the Immobilization of Glucose Oxidase on γ-Polyglutamic Acid Film

Fine needle-type glucose sensors with an outer diameter of less that 0.2 mm were fabricated using a low-cost biodegradable γ-polyglutamic acid (PGA) not only as a glucose oxidase (GOx) immobilizing material but also as a permselective inner membrane. PGA film was prepared on cellulose acetate-coated Pt-Ir wire electrode, and GOx was covalently immobilized on its surface using water-soluble carbodiimide. The obtained electrode was practically not affected by the existence of electroactive compounds and provided long-term stability for approximately one month. It also functioned in horse serum with good linear relationship between the current and glucose concentrations within the range of 2.8 to 22.4 mM.


Selectivity and Regeneratability Evaluation of Antigen Analogous-Modified Surface Film for Polychlorinated Dibenzodioxin Immunosensor Using Surface Plasmon Resonance Measurement

ダイオキシン計測のための表面プラズモンイムノセンサー用感応膜の試作と評価

For the development of a sensitive and accurate immunosensor, the production of a highly specific surface to the corresponding antibody is essential. Moreover, a specific surface having good reusability is worthwhile for constructing a prompt auto-monitoring immunosensing system. In this study, antigen analogous-modified gold substrates having a specific adsorption property to an anti-dioxin antibody, were prepared by the immobilization of 2,4,5-trichlorophenoxy (TCP) derivatives on a gold surface using various methods. An anti-dioxin antibody, which has a good correlation immunoaffinity with the total toxic equivalent quantity (TEQ) of polychlorinated dibenzo-p-dioxins, was employed as a specific antibody, and the specification of the surface was evaluated by a comparison of the surface plasmon resonance (SPR) responses to a specific anti-dioxin antibody and non-specific anti-hemoglobin antibody. In order to obtain a firm and stable immobilization of TCP, a carboxyl group was introduced on gold by a self-assemble monolayer (SAM) technique, and TCP derivatives were attached to the SAM surface with covalent bonding directly and indirectly through the presence of a hexamethylene chain, bovine serum albumin (BSA), and ethylene glycol oligomer (EGO). A TCP derivative-immobilized substrate, prepared using BSA, showed poor reusability. A TCP derivative-immobilized substrate having EGO was highly specific to an anti-dioxin antibody, while that prepared by the direct immobilization of TCP and with introduction of a hexamethylene chain presented nonspecific adsorption. In addition, a TCP derivative-immobilized substrate having EGO showed a good reproducible response from the second repetition, and was reusable more than seven times.


A Senior High School Chemistry Laboratory Class Observed by University Students

Journal of Engineering Education Research


Production of Chemistry Laboratory Class for Senior High School Freshmen

Chemistry laboratory class was produced for senior high school freshmen with the cooperation of university staffs, high school teachers and the university students. Although the students who will take the lab class are senior high school freshmen, we decided to prepare four experiments that are simple and have highly visible reactions or transformation. That is, 1) Water purification, 2) Surface modification, 3) Briggs-Rauscher reaction, and 4) Polymer synthesis and characterization. After the safety guideline and experiment instructions by the faculty staffs, two teaching assistants (TAs) supervised each experiment. Since taking a direct part in it will provide stronger impact than only being one who is just watching the experiment, all experiments contained some process that the high school students must handle the reagents, tools or the equipment, by themselves. Although, the operation performed by the students was limited to a series of simple actions, the various unique phenomena presented by the experiments impressed the students. The lab class was fruitful not only for high school students, but also good for university students. The lab class provided good opportunity for them to improve the abilities to teach and guide someone.


Synthesis and Electropolymerization of Phosphorylcholine-Containing Pyrroles and their Hemocompatible Properties

A series of N-substituted pyrroles having phosphorylcholine with different methylene chain length between pyrrole group and phosphorylcholine group, were synthesized and the electropolymerization was performed in aqueous solution. The methylene chains were trimethylene (n = 3), pentamethylene (n = 5), nonamethylene (n = 9), and undecamethylene (n = 11), for 3-(1-pyrrolyl)propyl-2-(trimethylammonium)ethyl phosphate (5a), 5-(1-pyrrolyl)pentyl 2-(trimethylammonium)ethyl phosphate (5b), 9-(1-pyrrolyl)nonyl-2-(trimethylammonium)ethyl phosphate (5c), and 11-(1-pyrrolyl)undecyl-2-(trimethylammonium)ethyl phosphate (5d), respectively. Although electropolymerized films were produced from all pyrrole derivatives, thick and black polymer films were prepared from 5a, 5b and 5c. Pyrrole derivative with long methylene-chain 5d provided only colorless or slightly blackish thin film. Hemocompatibilities of the polymer from 5a, 5b and 5c were evaluated by platelet rich plasma (PRP) contacting studies and scanning electron microscopy (SEM) observation. The results indicated that these polymers have excellent hemocompatibility.


Fabrication of Implantable Fine Needle Type Glucose Sensor Using gamma-Polyglutamic Acid

Implantable fine needle type glucose sensors with an outer diameter of less that 0.2 mm were fabricated using a low cost and non-animal origin polyamide, -polyglutamic acid (PGA) as a glucose oxidase (GOx) immobilizing material. Two types of PGAs, -polyglutamic acid (PGAH) and -polyglutamic acid sodium salt (PGANa), were employed to prepare GOx immobilized film by covalent attachment of GOx using water-soluble carbodiimide (EDC). Nafion/cellulose acetate composite film and polyurethane/polydimethylsiloxane composite film were employed as a permselective inner film and a biocompatible outer film, respectively. The procedure of enzyme-immobilized film fabrication affected the stability of the sensor, that is, GOx immobilized film prepared by pouring a mixture solution of GOx and EDC on a PGA precoated surface showed higher sensor stability than that prepared by pouring a mixture solution of GOx, PGA and EDC. Although, obvious differences on sensor properties were not observed between the use of PGANa and PGAH, the electrode prepared with PGAH had lower swelling degree. The glucose sensors prepared with both PGANa and PGAH were practically not affected by the existence of electroactive compounds such as uric acid, and provided long-term stability of approximately 5 weeks. These sensors showed good performance also in horse serum.


Flow-Injection Amperometric Determination of Urine Glucose Using Platinum Electrode Modified with Nafion and Saccharide Substitued Polypyrrole

ナフィオン及び糖鎖を有するポリピロールを修飾した白金電極を用いた尿中グルコースのフローインジェクション/アンペロメトリック検出

A flow-injection amperometric analysis system for the determination of glucose in human urine was analyzed. The glucose sample was mixed with glucose oxidase, and was introduced into the flow-injection system. Hydrogen peroxide produced by an enzymatic reaction was amperometrically detected by a platinum electrode modified with Nafion, and an electrochemically polymerized saccharide substituted polypyrrole. The influence of electroactive compounds such as ascorbic acid, uric acid, and acetaminophen to the glucose response observed in this system was negligible. A good linear relationship between the glucose concentration and the response current was obtained within a concentration of up to 22.4 mmol dm-3. The relative standard deviation for ten replicate analyses of 5.6 mmol dm-3 glucose in human urine was 7.4%.


Characterization of a glucose sensor prepared by electropolymerization of pyrroles containing a tris-bipyridine osmium complex

A glucose sensor was developed by electrocopolymerization using pyrroles containing a tris-bipyridine (bpy) osmium complex (Os-py), pyrrole (py), pyrrole propanoic acid (PPA) and glucose oxidase (GOx) to improve the key performance characteristics, such as the sensitivity, selectivity, and long-term stability. Tris-bipyridine osmium pyrrole complexes with four different methylene moieties were utilized to correlate the methylene length with the glucose sensor performance. The electrocatalytic response of glucose was clearly observed at electrodes modified with Os-py, except for the electrode immobilized with the Os-py complex containing the shortest methylene moiety. The current response to glucose increased up to a concentration of 100 mmol dm(-3). The electrocatalytic response to glucose at the [Os(bpy)(2)(py(6)-bpy)](2+/3+)/py/PPA/GOx electrode was stable for more than 100 days. Dissolved oxygen and potential interference compounds (ascorbic acid, uric acid, and acetaminophen) minimally perturbed the current response to glucose at the [Os(DM-bpy)(2)(py(6)-bpy)](2+/3+)/py/PPA/GOx electrode. Based on these results, a longer methylene moiety appears to improve the performance characteristics of a glucose sensor fabricated via the electropolymerization of tris-bipyridine osmium pyrrole complexes.


Indirect electroreduction of imines and diimines using a sacrificial sulfur-graphite electrode.


Preparation of Glucose Sensor Using Polydimethylsiloxane / Polypyrrole Complex

ピロール基のN-置換基末端に糖鎖を有するピロ-ル誘導体1-(6-D-gluconamidohexyl) pyrrole (GHP)を用いて作製したグルコースセンサは, 25℃の環境下における測定では，120日以上のセンサ寿命を示したが，生体内温度にあたる40℃での測定(保存温度も40℃)では，センサ応答の安定性が著しく低下した．これは40℃において酵素固定膜の膨潤及び剥離が著しいことが原因であった．そこで酵素固定膜の膨潤抑制及び電極との密着性·親和性を向上させるため，生体適合性を有し，バイオマテリアルとして用いられているポリジメチルシロキサン(PDS)とナフィオンの両ポリマ-を導入した酵素固定電極を作製した．その結果，40℃で測定及び保存を行った場合においても，電極作製直後から約30日間は安定した応答電流が得られることが確認された．またPDS及びナフィオンを含むGHPの電解重合膜の富血小板血漿吸着試験を行ったところ，優れた生体適合性を有することがわかった．

International Journal of Modern Physics B


Design and Construction of Automated Amperometric Immunosensing System

2種類のIgGクラス抗トランスフェリン抗体を用い，トランスフェリンの定量を行うことのできるセンサの作製を行った．これまでの測定では，バッチ法を用いて行っていたため，測定には煩雑な作業が必要であったが，本研究においてはフローシステムを導入したことにより，測定の自動化が可能になり，測定時間も従来の測定に比べ，約1/4の12分間/サンプルで行うことが可能になった．また高価でかつ煩雑な作製手順を要する抗体固定電極を，繰り返し使用(リサイクル)するため，使用後の電極を，4℃の条件下で酸性処理を行ったところ，10回の再利用が可能であることを確認している．また抗原抗体反応により電極表面に結合しているフェロセンの電子授受を効率よく行うため，これまではフェロセニルメチル-3-(ピロール-1-イル)プロピルジメチルアンモニウムブロマイドの電解重合膜を用いていたが，今回より安価なポリピロール膜を使用したが，再現性もよく，高感度な定量測定が可能であった．


Introduction of sulfur atoms into trifluoromethylated alkenyl sulfones and chlorides using a reactive sulfur-graphite electrode


Characterization of glucose sensor prepared with the electropolymerized pyrrole containing a saccharide unit.

酵素の存在下，ピロールやその誘導体の電解酸化重合により，電極表面に酵素を固定する方法は，酵素活性を保持したまま，容易に微小酵素固定電極を作製する方法として興味深い．しかしながら，この方法では酵素は，ただ単にポリピロールマトリックス中に包括的に保持されているため，電極表面に安定に固定されているとは言い難く，センサ寿命の面で改善が必要である．そこで本研究では，糖鎖を有する化合物が酵素と水素結合することに着目し，糖鎖を有するピロール誘導体，1-(3-D-グルコンアミドプロピル)ピロール(GPP) を用い，より安定に酵素が固定された酵素固定電極の作製を試みた．酵素としてはグルコースオキシダーゼを用い，得られた電極のグルコースセンサ特性についても検討を行った．また生体内に存在する電気化学的活性な物質の影響を抑制する効果が報告されている1,2-フェニレンジアミン(PD)の電解重合膜(PPD膜)を導入した電極の作製もあわせて行い，その効果について検討を行った．GPP電極の経過日数と応答電流の関係を調べた結果，作製から4日目に電流値の減少が見られたものの，2週間以上にわたり，安定した応答電流を示した．一般に，電解重合により作製した酵素固定電極は，作製後，数日間は著しい応答電流の変化が見られるが，今回作製した電極が，作製直後から，比較的安定した応答電流を示したのは，GPP膜内に存在する酵素は，ただ単に包括的に固定されているだけでなく，糖鎖と酵素の間で水素結合が形成されることにより，より強固に固定されているためではないかと考えられる．


Properties of glucose sensor based on the immobilization of glucose oxidase in N-substituted polypyrrole film

ピロールやその誘導体を酵素の存在下で電解重合することにより，酵素を電極表面に固定する電解重合法は，酵素を局部的に固定した微小酵素センサを簡単に作製する方法として興味深い．しかしながら，この方法で作製した電極では，酵素は電極表面に形成されたピロールの重合膜に包括的に修飾されているため，十分安定に固定されているとは言えない．そこで本稿では，酵素を電解重合法により局部的に固定し，さらに水溶性カルボジイミド(EDC)で架橋化させることにより，安定した酵素膜を有するセンサの作製を試みた．また内部膜として生体内に存在する電気化学的活性物質の透過抑制に効果があると言われる1,2-フェニレンジアミン(PD)の電解重合膜(PPD膜)を用いた電極も作製した．酵素としてはグルコースオキシダーゼを，電解重合性モノマーとしては，EDCによる酵素との共有結合性を考慮して，ピロールのN-置換基末端にカルボン酸基を有する3-(1-ピロール)プロピオン酸 をそれぞれ用いた．その結果，得られた電極は，グルコース濃度約7mM まで良好な直線関係が見られた．また，経過日数と応答電流の関係を調べた結果，作製後3日間は，応答電流の減少が見られたが，以降約20日間以上にわたり，安定した応答電流を得られた．


Properties of glucose sensors prepared by the electropolymerization of pyrroles containing phosphatidylcholine (II)

近年，リン脂質の一つであるホスファチジルコリンの極性部を持つポリマーは，優秀な生体適合性(血液適合性)を有することから，バイオマテリアルとして注目されている．一方，ピロール基を有する化合物を酵素の存在下で電解重合を行うと，容易に酵素を局部的に固定した電極が作製できる．そこで我々は以前，N-置換基末端にホスファチジルコリンの極性部を有するピロール誘導体を用い，グルコースオキシダーゼ固定電極の作製したところ，作製から2ヶ月以上に渡り，安定した応答電流を与えることがわかった．しかしながら，生体内に存在する電気化学的活性物質(妨害物質)の応答電流への影響を調べたところ，いずれの電極の場合においても，アスコルビン酸，尿酸の存在が応答電流に大きく影響を与えることがわかった． そこで本研究では妨害物質の影響を抑制する効果が報告されている1, 2-フェニレンジアミンの電解重合膜(PPD膜)やナフィオン膜を導入した酵素固定電極の作製を行い，そのセンサ特性について検討を行った．その結果，PPD膜およびナフィオン膜の導入は，センサ寿命の向上並びに妨害物質の影響の低減に有効であることが分かった．


Preparation of glucose sensors using the Langmuir-Blodgett technique

Langmuir-Blodgett (LB)法を用いて作製した酵素固定電極は，酵素が脂質単分子膜の中に取り込まれた，生体膜のような構造を持つことが期待され，興味深い．しかしながらこれまでに報告されているLB法を用いた酵素センサでは，酵素が安定に固定されていないことやセンサ応答が遅いなど，またこれらを克服するには煩雑な作業が要求された．本稿では酵素を取り込む膜の強度を高めるため，脂質膜としてリン脂質類似構造を持つポリマーを用い，白金線電極上にグルコースオキシダーゼを固定した電極の作製を試みた．その結果，得られたグルコースセンサは応答が速く，約30日間は安定した応答電流を示すことがわかった．


Properties of glucose sensors prepared by the electropolymerization of pyrrole containing a gluconyl group

ピロールやその誘導体を酵素の存在下で電解重合することにより，酵素を電極表面に固定する電解重合法は，酵素を局部的に固定した微小酵素センサを簡単に作製する方法として興味深い．しかしながら，この方法で作製した電極では，酵素は電極表面に形成されたピロールの重合膜に包括的に修飾されているため，十分安定に固定されているとは言えない．そのため我々は以前，糖鎖を有するピロール誘導体を用いれば，糖鎖が酵素と水素結合を形成することにより，酵素がより強固に固定された酵素固定電極の作製が期待できると考え，ピロールのN-置換基末端からメチレン鎖を3つ挟み糖鎖を有するピロール誘導体を用い，酵素(グルコースオキシダーゼ)を固定した電極の作製を行った．その結果，グルコースに対して作製直後から約3ヶ月間に渡りセンサ応答を示したが，センサ感度は徐々に減少した．これは，用いたピロール誘導体がピロール環と比較的嵩高い糖鎖との距離が近いため，電解重合膜の伝導度が低く，重合度の高い膜が形成されず，酵素を十分に安定に固定できなかったためだと考えられた．一般にピロールに長いメチレン鎖を置換基として導入することは，ポリマーの伝導度の低下を導くが，ピロール環と嵩高い糖鎖との間隔をメチレン鎖で離すことは，得られたポリマーのピロール環同士が平面構造を形成するのに有利に働くことが予想され，伝導度の向上が期待される．そこで本稿ではピロール環と糖鎖と間隔をメチレン鎖6に広げたピロール誘導体の合成を行い，電解重合法による酵素固定電極の作製およびそのグルコースセンサ特性についての検討を行った．その結果電極作製直後から4ヶ月以上の長期に渡り，感度変化のない，安定したセンサ応答を示した．


Properties of glucose sensors prepared by the electropolymerization of a positively charged pyrrole derivative

ピロール類等の電解重合により酵素固定を行う方法は，操作が容易等種々の特徴を有するが，酵素が遊離しやすい等の欠点が見られた．本研究ではグルコースオキシダーゼ等の酵素が中性環境ではマイナスの帯電していることに着目し，ピロール環のN-置換基末端にプラスチャージを有するピロール誘導体の合成を行い，酵素固定電極の作製に用いた．その結果20日間安定した応答を示すセンサの作成が可能であった．またカチオン交換膜であるナフィオンを予め被覆した後，酵素を固定した電極の作製も行ったが，この場合50日間以上安定した応答を示した．また生体液中に存在する電気化学的活性物質のセンサ応答に対する影響を調べたところ，アスコルビン酸，尿素，フルクトースおよび解熱剤として良く服用されるアセトアミノフェンの影響は見られなかったが，尿酸については無視できる値ではなかった．


Electroreduction of 2-cyclohexen-1-one on metal-solid polymer electrolyte composite electrode

2-シクロヘキセンー1-オンの電解還元における電極材料の影響を種々金属修飾固体高分子電解質電極を用いて行った．固体高分子電解質にはナフィオンとセレミオンを，修飾する金属としては，白金または金を用い，白金や金に更にビスマスや亜鉛を修飾した電極も作製し電解を行った．生成物としてはシクロヘキサノン，2-シクロヘキセンー1-オール，および/またはジケトン(二量体)が得られ，用いる電極の種類によって生成物も異なった．例を挙げると白金修飾ナフィオンにビスマスまたは亜鉛を修飾させた電極を用いた電解では，シクロヘキサノンが選択的に高い電流効率で生成した．また金修飾ナフィオンにビスマスを修飾した電極を用いた電解では，二量体が選択的に得られた．


Electroreductive aromatization of imines and diimines

種々の電極を用いたイミン類およびジイミン類の電解還元によるアミン類の合成を行った．アミン生成物は，電極として水銀<白金<グラッシーカーボン<グラファイトフェルトの順に大きくなった．またグラファイトフェルト表面に亜鉛やビスマスを修飾させることにより，更に収率を向上させることが可能であった．


Electrooxidation of benzyl alcohol on Pt-Nafion composite electrode


Electrochemical method to vinyl fluorides. Electrochemical cleavarage of 1-fluoro-2-arylvinyl phenyl sulfoxides in acetonitrile


Electroreduction of acetophenone on Pt-Nafion composite electrode


Synthesis and polymerization of 2-{(2-methacryloyloxy)ethyldimethylammonio}ethyl p-substituted phenyl phosphates


The impedance study of the oxidation of formic acid at a platinum electrode


Characterization of N-substituted polypyrrole thin-film electrode having immobilized glucose oxidase


Electrochemical method to vinyl fluorides - I. Cathodic elimination of 1-fluoro-2-arylvinyl phenyl sulphones in acetonitrile


Synthesis and Polymerization of 2-{2-(Methacryloyloxy)ethydimethylammonium}ethyl n-Alkyl Phosphate


Electrochemical carboxylation of b-methylsulphenyl-b-methylsulphonylstyrene in N,N-dimethylformamide containing carbon dioxide


Electroreductive desulfurization and carboxylation of a,b-bis(methylsulfonyl)styrene in nonaqueous media


Electroreductive carboxylation of 1-methylthio-1-p-tolylsulfonyl-2-arylethenes in N,N-dimethylformamide


生体膜の主構成成分であるリン脂質は，膜の強度を保つ物理的な機能に加え，選択透化性等の特異性を有することが知られている．またリン脂質の中でも脳や神経等に多く存在するホスファチジルコリンの極性基を有するポリマーは，生体適合性材料として注目されている．これまでの報告されている研究のほとんどは，ビニルポリマー等の側鎖にホスファチジルコリンの極性基を導入しているものであるが，本報に示したポリマーは，ポリマー主鎖にホスファチジルコリンの極性基を有するものであり，P-Oマイナスと四級アミンのプラスが交互に並ぶ全く新しいポリマーである．重合は2-オキソー1,3,2ージオキサホスホラン環とジメチルアミンの両方を有するモノマーを極性溶媒で加熱することにより，2-オキソー1,3,2ージオキサホスホラン環がジメチルアミンにより開環し，分子間結合を形成して起こる．得られたポリマーは，高分子電解質的挙動を示した．


β,β-ビス(メチルスルホニル)スチレンのアセトニトリル/水銀電極系における電解還元反応


Polymeric phospholipid analogs. XV. Polyacrylamides containing phosphatidylcholine

体膜の主構成成分であるリン脂質は，膜の強度を保つ物理的な機能に加え，選択透化性等の特異性を有することが知られている．またリン脂質の中でも脳や神経等に多く存在するホスファチジルコリンの極性基を有するポリマーは，生体適合性材料として注目されている．本報では，ホスファチジルコリンの極性基を有し新規アクリル及びメタクリル系ポリマーの合成を行った．またポリマーに疎水性を増すためにベンゼン環をアミド結合を介して導入した．

Journal of Macromolecular Science: Part A - Chemistry


Polymeric phospholipid analogs (18). Synthesis and properties of vinyl polymers containing both vitamin E and phosphatidylcholine analogous moieties

生体膜の主構成成分であるリン脂質は，膜の強度を保つ物理的な機能に加え，選択透化性等の特異性を有することが知られている．またリン脂質の中でも脳や神経等に多く存在するホスファチジルコリンの極性基を有するポリマーは，生体適合性材料として注目されている．一方，ビタミンEであるαートコフェロールは，体内において抗酸化作用を行うのに加え，様々な薬理活性を示す．本報では，ホスファチジルコリンの極性基とビタミンEが共有結合で結びついたメタクリル酸モノマーの合成を行い，更にそのラジカル重合によるポリマーの合成を行った．得られたポリマーの膜電位を調べたところ，膜が負に帯電していることが分かった．αートコフェロールの代わりにコレステロールを用いたポリマーとでは，正に帯電しており，興味深い結果が得られた．


Polymeric phospholipid analogs (17). Synthesis and properties of vinyl polymers containing both cholesterol and phosphatidylcholine analogous moieties

生体膜の主構成成分であるリン脂質は，膜の強度を保つ物理的な機能に加え，選択透化性等の特異性を有することが知られている．またリン脂質の中でも脳や神経等に多く存在するホスファチジルコリンの極性基を有するポリマーは，生体適合性材料として注目されている．本報では，リン脂質と同じく生体膜の主構成成分である中性脂質のコレステロールとホスファチジルコリンの極性基の両方を有するメタクリル酸モノマーの合成並びにそのラジカル重合により得られたポリマーの合成を行い，その特性について調べた．得られたポリマーのキャストフィルムを作成し，膜電位を調べたところ，膜が正に帯電していることが分かった．


FABRICATION OF GLUCOSE OXIDASE-IMMOBILIZED ELECTRODE USING ELECTRODEPOSITION METHOD

電解析出法を用いたグルコース オキシターゼ固定電極の作製

Glucose oxidase (GOx)-immobilized electrodes were prepared by the combination of electrodeposition and photopolymerization. Methacryloyl choline chloride (NMA) were employed as photo-polymeriable methacrylates and were added in the enzyme- electrdeposition solution, in order to be entrapped in the enzyme film. In order to investigate the enzyme film formation behavior during the electrodeposition process, quartz crystal microbalance (QCM) technique was employed. QCM measurement results indicated that the amount of deposit increased continuously up to around 15 minutes, while the decrease of deposit was observed after that time. The amount of GOx immobilized on the electrode was also measured using Amplex Red Assay Kit and showed that the decrease of deposit was parallel with the decrease of GOx on the electrode. However, the amount of enzyme on the electrode started to increase again after electrodeposition time of 40 minutes. The glucose sensor sensitivity of the obtained electrode showed a good correlation with the amount of enzyme immobilized on the electrode.


Preparation and evaluation of low-invasive sensor for in vivo glucose monitoring

体内グルコースモニタリング用低侵襲型センサの作製およびその評価

A fine needle type glucose sensor, which has sensing region on the tip of a fine tapered electrode, was prepared using tapered PEEK tube with platinum-iridium alloy wire. Glucose oxidase was immobilized on the surface of Pt-Ir electrode using the combination of electrodeposition and electropolymerization procedures. The obtained sensor showed good response with sufficient linear relationship between response current and glucose concentration. Long-term stability of the obtained electrode was evaluated for 35 days. After initial change of response current for a week, constant response current was obtained for 1 month and approximately 80% of the initial sensor response remained. In vivo measurement evaluation of the electrode was performed using rabbit. Considerable glucose sensor response change due to the trend of glucose concentration was observed.


Preparation of Enzyme Immobilized Electrodes Using Cellulose Dispersion and Their Application to Sensors

セルロース分散液を用いた酵素固定膜の作製およびそのセンサへの応用

Biorecognition elements, such as enzyme and antibody, were immobilized on Pt-Ir wire electrode by the combination of electrodeposition and photopolymerization. Glucose oxidase was employed as enzyme and glucose sensor properties of obtained GOx-immobilized electrode were investigated. Sensor sensitivity was significantly influenced by the procedure to prepare electrolytic solution for enzyme electrodeposition, which was considered to be due to the difference in enzyme dispersibility in solution. Methacrylates with functional group, such as epoxy and quaternary amine, were also used beside hexyl methacrylate and hexandiol dimethacrylate, in order to introduce interaction between enzyme and entrapping polymer film.

Proceedings of the Chemical Sensor Symposium


Improvement of chemistry laboratory class at senior high school based on continuous cooperation among high school, university and graduate school, and its application to a chemistry event for children

高大院連携化学実験の継続実施による改善と体験イベントへの活用

Journal of University Education Research


Preparation of biorecognition element-immobilized electrodes using electrodeposition method and their application to sensors

電解析出法を用いた生体識別素子固定電極の作製及びそのセンサへの応用


低侵襲型グルコースセンサの作製及びその評価

低侵襲型グルコースセンサの作製及びその評価


電解析出法および光重合法を組み合わせた酵素固定電極の作製

電解析出法および光重合法を組み合わせた酵素固定電極の作製


Cooperative education among high school, university and graduate school through chemestry laboratory class at senior high school

化学実験出張講義を通した高大院連携教育の試み


GLUCOSE MONITORING IN BLOOD VESSEL WITH FINE NEEDLE TYPE GLUCOSE SENSOR

微細針状グルコースセンサを用いた血管内グルコースモニタリング


New fine needle type glucose sensors were fabricated by immobilizing glucose oxidase (GOD) on the surface of the platinum sputtiring film formed on super-elastic Ni-Ti alloy wire. The immobilization of GOD was successfully performed on the platinum sputtiring film by the electropolymerization of 1-(6-D-gluconamidohexyl) pyrrole (GHP) in the presence of GOD. The glucose sensor properties of the obtained electrodes were performed in the phosphate buffer solution (pH 7.4) containing NaCl. Although the response current increased with the increase of glucose concentration of up to 22 mmol dm-3, the linear relationships range was up to 5 mmol dm-3. The response current of the obtained electrode reached to a stable current within 20 seconds.


Preparation of platinum-coated pet film electrodes and their application to glucose sensors

白金被覆PETフイルム電極の作製およびそのグルコースセンサへの応用

In order to improve the stability of Pt thin film electrode prepared on the surface of polyethylene terephthalate (PET) film, three types of binder, Nafion, polyethylene imine (PEI) and silica formed from perhydropolysilazane (PHPZ), were introduced on the surface of PET film prior to Pt sputtering. The strength and stability of obtained Pt-coated PET electrodes were evaluated by pencil scratch test and the observation of surface after 40 C water immersion test. By the use of Nafion and PEI, both pencil scratch hardness and stability in water improved compared with that without the binder, while silica did not perform as a useful binder. Glucose oxidase (GOx) was immobilized on the surface of Pt-coated PET electrodes using electrodeposition and electropolymerization technique and their glucose sensor properties were examined. Glucose sensors prepared using Nafion and PEI as binder provided good response to glucose while the background current were somewhat high. Although the glucose sensor prepared using Nafion as binder showed poor response after 20 days of use, the sensor with PEI binder provided clear glucose response with lowered background current.


人工生体膜のソフトナノテクノロジー

Soft nanotechnology is technology that treats soft and wet materials such as self-assemblysystems in a living body under a relatively moderate condition. We focus our attention on the sizecontrol of liposomes, namely lipid bilayer membranes and performed the soft nanotechnology insizing of liposomes under high pressure. Two high-pressure sizing techniques, a method ofcontinuous pressure relaxation using a phase transition between gel and liquid crystalline phases ofthe bilayer membrane and that of a pressure-induced gel phase using a phase transition betweenbilayer and nonbilayer membranes, were applied to liposomes of distearoylphosphatidylcholine, andthe effects of the both methods were considered. Further, the application of giant liposomescontrolled by high-pressure sizing to microsensor was briefly described.

Bulletin of Institute of Technology and Science, The University of Tokushima

徳島大学大学院ソシオテクノサイエンス研究部研究報告


学会レポート 第46回化学センサ研究発表会

学会レポート 第46回化学センサ研究発表会


PREPARATION OF NEEDLE TYPE GLUCOSE SENSORS USING γ-POLYGLUTAMIC ACID

γーポリグルタミン酸を用いた微細針状グルコースセンサの作製

Long-term stability of glucose oxidase (GOx) immobilized electrode was improved by the introduction of dietary fiber, gamma-polyglutamic acid (PGA) due to the formation of poly-ion complex between positively charged polypyrrole and negatively charged PGA, which stabilized the enzyme immobilized film. The electrode prepared by the electropolymerization of 1-(6-D-gluconamidohexyl)pyrrole in the presence of GOx and PGA showed best performance in both stability and sensitivity. Outer layer film coating of polyurethane provided good response in horse serum measured at 40℃. Although, the influence of electroactive compounds in biological fluid such as ascorbic acid was low, the influence of uric acid to sensor response was unneglectable.


Preparation and evaluation of a low invasive needle type enzyme sensor

低侵襲針状酵素センサの作製およびその評価

A unique needle type glucose sensor which can be used by inserting only the tip of the sensor in the sample was fabricated. In order to maintain enough area for enzyme immobilization and platinum electrode surface, a cave with platinum surface was formed at the tip of the sensor. The enzyme glucose oxidase was immobilized on the platinum surface located in the cave by the combination of electrodeposition and electropolymerization of o-phenylenediamine. Amperometric responses of the prepared electrodes to glucose were examined by measuring the electrooxidation current at a potential of 0.60 V (for hydrogen peroxide detection) in 0.1 mol dm-3 phosphate buffer solution (pH 7.4). The obtained sensor showed good response with good linear relationship with glucose concentration up to 24 mmol dm-3, which is actually wider than general sensor with sensing part outside of the electrode. This may due to the effective reproduction of oxygen generated by the electrooxidation of hydrogen peroxide, which all occurred in the cave. The application of this sensor to a low invasive glucose sensor fabrication is highly feasible.


DEVELOPMENT OF SURFACE PROCESSING TECHNIQUE

ペルヒドロポリシラザンを用いたタンパク質吸着抑制表面形成技術の開発

Hydrophilic surface modification was performed on glass and stainless plate using perhydropolysilazane (PZ) and polyethylene glycol (PEG). The water contact angle was lower on the surface prepared using higher molecular weight PEG. Although, the introduction of monoalkoxy PEG to the surface of silica was performed without any matter, dialkoxy PEG did not react with PZ and silica film without PEG was obtained on the surface. Molar ratio of protein adsorption of fibrinogen to albumin (F/A molar ratio), which was adopted as the indicator of biocompatibility, was measured. The F/A molar ratio was lowered by the surface modification of PEG. PEG surface modification contributed to improve the biocompatibility.


DEVELOPMENT OF PRECISE ENZYME-LOCALIZING TECHNIQUE FOR MULTI-CHANNEL

微細針状マルチチャンネルセンサ作製を目的とした微小領域への選択的酵素固定技術の開発

In addition to precise localization of enzyme on a minute sensing region, prevention of the enzyme adsorption onto inappropriate electrode surface is essential on the fabrication of multichannel enzyme sensor. Masking of a platinum electrode surface was performed by dipping the electrode in allyl derivatives solution and was removed by applying a potential of 1.50 V (vs. Ag/AgCl). The effect of the introduction of allyl derivatives to prevent enzyme adsorption was evaluated by using electrochemical procedure and optical procedure. Negatively charged allyl sulfonic acid could prevent the adsorption of glucose oxidase significantly, since the pI of GOx is 4.2 and negatively charged at neutral media. Optical procedure provided reliable results than that obtained from electrochemical procedure.


PREPARATION OF IN VIVO MEASUREMENT TYPE BIOSENSOR USING SUPER-FLEXIBLE

超弾性合金を芯材に用いた体内埋め込み測定用バイオセンサの作製

In the development of in vivotype glucose sensor, miniaturization of the sensor size and flexibility is quite importance to reduce damage to the tissue from sensor implantation.Super flexible Ni-Ti alloy wire with a diameter of 100mm was applied as a core material in order to obtain fine and flexible sensor. Gold plating and platinum plating were performed on Ni-Ti wire to obtain sensing region with platinum surface and was applied for glucose sensor. Pt sensing region prepared on Au plated Ni-Ti presented good response to hydrogen peroxide and the applied glucose sensor also showed good response to glucose. Back ground current and current noise were significantly lower than that prepared from Pt sputtering on Ni-Ti wire.


DEVELOPMENT OF A MULTICHANNEL BIOSENSOR FOR IN VIVO MEASUREMENT

インビボ測定用マルチチャンネルセンサの開発

Glucose/lactate dual-channel needle type biosensor with the total diameter of less than 250 μm was fabricated by the combination of glucose oxidase (GOx) immobilized tube electrode and lactate oxidase (LOx) immobilized wire type electrode. GOx immobilized tube electrode was prepared by the formation of sensing site on Pt-coated polyimide tube and immobilizing GOx by electrodeposition of GOx followed by electropolymerization of o-phenylenediamine. LOx immobilized wire type electrode was also prepared by first enzyme electrodeposition step and then electopolymerization step. Both GOx immobilized tube electrode and LOx immobilized wire type electrode showed good response and showed good linear response up to 15 mmol dm-3 in both 0.1 mol dm-3 phosphate buffer solution (pH 7.4) and in horse serum. No crosstalk was observed when glucose/lactate dual-channel needle type biosensor was tested in 0.1 mol dm-3 phosphate buffer solution (pH 7.4). In vivo measurement in rats with the dual channel sensors is under investigation.


DEVELOPMENT OF FLEXIBLE GLUCOSE SENSORS FOR IN VIVO MEASUREMENT

インビボ測定用フレキシブルグルコースセンサの開発

Important design considerations for in vivo type glucose sensors include miniaturization and flexibility, specificity, biostability, long useable life span, and safety. In the design of the sensor, miniaturization of the sensor is of primary importance. Miniaturization and flexibility of the sensor will help reduce the damage to the tissue from sensor implantation. Sensors fabricated from small diameter platinum (<0.1mm) can be brittle, therefore create a greater risk of breakage. In this study, flexible super-elastic Ni-Ti alloy wire was used as the core material with platinum thin film sputtered on its surface. A comparison of the sensor performance between platinum wire and platinum sputtered Ni-Ti wire is demonstrated. Glucose oxidase immobilization was performed by crosslinking with glutaraldehyde and bovine serum albumin. The sensor was fablicated with an integral Ag /AgCl reference to facilitate in vivo testing. This in vivo type glucose sensor showed remarkable anti-interferent selectivity, moreover with a linearity range extending up to 22.4 mM in the phosphate buffer solution.


DEVELOPMENT OF SURFACE PROCESSING TECHNIQUE FOR NONSPECIFIC ADSORPTION INHIBITION

非特異吸着抑制表面加工技術の開発

The adaptation of metals surface was performed by the surface reaction of perhydropolysilazane (PZ) in the presence of polyethylene glycol (PEG). Surface hydrophilic property was able to control by the reaction of PEG with PZ and the usage of PEG at various molecular weight. Biocompatibility of platinum treated with PZ and PEG was evaluated by blood platelet adhesion test. The treatment significantly improved the biocompatibility of platinum. Potentiality and utility of new surface processing technique for biocompatibility treatment and nonspecific adsorption inhibition was strongly suggested.


FABRICATION OF NEEDLE TYPE MICRO GLUCOSE SENSORS

マイクロ針状グルコースセンサの作製

Glucose sensors with the diameter of less than 10 um were fabricated using super-flexible Ni-Ti alloy wire as a core material. The 150 um diameter of Ni-Ti alloy wire was reduced by a continuous dipping operation in etching solution. Ni-Ti surface was sputter coated with Pt film. The Pt surface was covered with silica leaving the unetched end bare for electric contact. Silica on the etched tip was removed in order to prepare sensing cavity. Glucose oxidase (GOx) was immobilized on the sensing cavity by the electropolymerization of 1-(6-D-gluconamidohexyl) pyrrole (GHP) in the presence of GOx. Performance characteristics of the fabricated micro glucose sensor were determined in phosphate buffered saline (pH 7.4). The response current increased with the increase of glucose concentration up to 22 mmol dm-3. However, the linear range went up to 11 mmol dm-3. The response time to 90% maximum current for the micro glucose sensor was 20 seconds.


THE CONTINUOUS MONITORING ESTIMATION USING FINE NEEDLE TYPE IN VIVO GLUCOSE SENSORS

微細針状グルコースセンサを用いた体内グルコース濃度連続測定評価

There are various desirable characteristics to consider when designing in vivo type glucose sensors; including miniaturization, specificity, biostability, long useable life span, and safety. Miniaturization of the sensor is an important feature because smaller devices are less invasive, both physically and psychologically. A miniaturized device will excite fewer pain receptors in the skin and will cause less tissue damage, thus less pain and improved performance. However, since miniaturization can lead to easy deformation and breakage of the sensor, it is difficult to fabricate sensors less than 200 μm diameter that retain enough flexibility and strength to insure proper in vivo function. In this study, super-elastic Ni-Ti alloy wire was used as the core material with platinum thin film sputtered on its surface. Glucose oxidase was then immobilized on the platinum surface and functional glucose sensor characteristics were investigated. In vivo measurement with the new flexible glucose sensor was attempted.


Preparation and properties of enzyme micro sensors


In vivo studies of implantable electrochemically fabricated glucose sensors


REPRODUCIBILITY EVALUATION OF IMMUNOSENSOR WITH ANTIBODY-IMMOBILIZED BEADS COLUMN (II)

抗体固定ビーズを用いた免疫センサの応答再現性評価 (II)

The reproducibility of the antibody-immobilized beads by the acidic antigen-antibody bonds cleavage treatment was performed using an optical procedure. The fluorescein derivative was conjugated to the antigen in order to determine the affinity of the immobilized antibody. The attempt to reduce the nonspecific adsorption of fluorescein-labeled antigen to immobilized antibody was also performed by adding polyethylene glycol and poly(2-methacryloyloxyethyl phosphorylcholine) in the reaction solutions. Although, both polymers were effective to reduce the nonspecific adsorption, either could eliminate the nonspecific adsorption. Fair reproducibility was observed for approximately first five repetition, while the affinity reduction of the immobilized antibody was inevitable by the acidic treatment of pH 3.


FABRICATION AND EVALUATION OF FINE NEEDLE TYPE ENZYME SENSORS

微細針状酵素センサの作製及びその評価

New fine needle type glucose sensors were fabricated by immobilizing glucose oxidase (GOD) on the surface of the platinum sputtiring film formed on super-elastic Ni-Ti alloy wire. The immobilization of GOD was successfully performed on the platinum sputtiring film by the electropolymerization of 1-(6-D-gluconamidohexyl) pyrrole (GHP) in the presence of GOD. The glucose sensor properties of the obtained electrodes were performed in the phosphate buffer solution (pH 7.4) containing NaCl. Although the response current increased with the increase of glucose concentration of up to 22 mmol dm-3, the linear relationships range was up to 5 mmol dm-3. The response current of the obtained electrode reached to a stable current within 20 seconds.


FABRICATION OF FINE NEEDLE TYPE BIOSENSORS FOR IN VIVO MEASUREMENTS

微細針状バイオセンサの作製

New needle type glucose oxidase immobilized glucose sensors were prepared by the electropolymerization of 1-(6-D-gluconamidohexyl) pyrrole (GHP) on the platinum wire electrode precoated with the solution of GHP, polydimethylsiloxane, and Nafion. In vitro measurement was performed in the phosphate buffer solution (pH 7.4) containing NaCl and bovine serum at 40C. The response current obtained in bovine serum was similar with that in phosphate buffer solution. This indicated that the sensor itself have excellent biocompatibility and the adsorption of protein was hardly prevented. Therefore, the outer coating of biocompatible film such as polyurethane, was not essential. In vivo measurement was performed using rats under gas anesthesia of isoflurane. The sensor was implanted in subcutaneous tissue. After the intraperitoneal injection of glucose (30% solution, 1.0 g kg-1 body weight), the sensor response increased and behaved good agreement with the blood glucose level measured in vitro ith glucose meter.


STABILITY EVALUATION OF ANTIBODY-IMMOBILIZED COLUMN FOR IMMUNOSENSOR USING OPTICAL PROCEDURE

抗体固定ビーズを用いた免疫センサの光学測定法による安定性評価

The stability of the antibody-immobilized beads packed column for immunosensor application was evaluated using an optical procedure. Agarose resin and glass beads were employed for the immobilization of the antibody and the antigen was labeled with fluorescein in order to determine the affinity of the immobilized antibody by fluorescent measurement. Luteininzing hormone (LH) and its IgG class monoclonal antibody (anti-LH) were employed. The stability of the anti-LH column was evaluated by repeating the acidic treatment (pH 3) that will reproduce the column by cleaving the antigen-antibody bond formed on the surface of the beads. Although, the affinity of the antibody immobilized column reduced slightly for the first five times, relatively good reproducible affinity was observed for more than ten repetitive measurements.


PREPARATION OF GLUCOSE SENSOR USING ORGANOPOLYSILOXANE/POLYPYRROLE COMPLEX FILM

ポリピロール/オルガノポリシロキサン複合膜を用いたグルコ-スセンサの作製

New glucose oxidase immobilized glucose sensors were prepared by the electropolymerization of 1-(6-D-gluconamidohexyl) pyrrole (GHP) and 6-(1-pyrrolyl)hexylphosphatidylcholine (PPC) on the platinum wire electrode precoated with the solution of pyrrole derivative (GHP and PPC) and polydimethylsiloxane. Although, the response of the electrode prepared from PPC was satisfactory obtained, no response was observed from the electrode of GHP. By the addition of Nafion into the precoating solution, the improvement of sensor sensitivity occurred and the electrode prepared from GHP also showed clear sensor response. Moreover, the introduction of Nafion was effective to improve the long-term stability of the enzyme immobilized electrodes. The electrode prepared from both Nafion and GHP performed excellent long-term stability. Relatively constant response current was obtained over 30 days in pH 7.4 phosphate buffer solution under the condition of 40 C measurement and storage temperatures.


DEVELOPMENT OF REACTOR/DETECTOR DEVIDED ANTIBODY SENSOR (II)

抗原抗体反応を用いたリアクター・ディテクター分離型センサの開発(II)

Reactor/detector devided antibody sensing system was developed using two monoclonal IgG class anti-rat transferrin antibodies (15C2H3 and 22A06D2). Agarose resin containing hydrazide was applied to immobilize 22A06D2 and ferrocene polymer was labeled to 15C2H3. After the sandwich formation (agarose resin=antibody-antigen-antibody=ferrocene polymer) was constructed proportionally to the transferrin concentration, the reactor was treated with acidic solution and the antibody=ferrocene polymer was released from the the reactor in order to be measured amperometrically at the detector. The relationship between the transferrin concentration and sensor response was measured in the range of 0 to 300 ng cm-3 and relatively good calibration curve was obtained. The antibody immobilized agarose resin was able to reuse at least 5 times.


Synthesis of N-Methyl-D-Glucamine Modified Chitosan Nanofibers for Boron Adsorption

The 3rd International Conference on Nanomaterials and Advanced CompositesProceedings of NAC 2022,Springer Proceedings in Physics


Immunosensor Accuracy is Improved by Coating Beads with Poly-2-[3-(Methacryloylamino)Propylammonio]Ethyl 3-Aminopropyl Phosphate

Poly-2-[3-(methacryloylamino)propylammonio]ethyl 3-aminopropyl phosphate (poly-3MAm3AP) is a polymer that contains phosphorylcholine groups which can attract water to form a water layer, and amino groups which can be used for the covalent attachment of receptors such as anti-LH (Luteinizing hormone) antibody and LH antigen. Poly-3MAm3AP was synthesized with the anticipation that it would aid the recognition of a large number of analytes and eliminate nonspecific adsorption. Poly-3MAm3AP was coated on beads and served as an antigen-antibody reaction interface. The specificity of this surface was evaluated using surface plasmon resonance (SPR) by comparing responses to specific anti-LH antibody and nonspecific anti-hemoglobin antibody. Poly-3MAm3AP did not adsorb nonspecific antibody due to the presence of free water associated with the phosphorylcholine moiety. An immunosensor system was fabricated by combining poly-3MAm3AP-coated beads containing immobilized anti-LH antibody with an optical detector. Poly-3MAm3AP not only reduced nonspecific adsorption, but also increased the amount of specific antibody-antigen interaction. These favorable characteristics are due to an increased amount of immobilized receptor, and an increased amount of space for antigen-antibody interaction arising from electrostatic repulsion within the poly-3MAm3AP electrolyte.


Selection of novel structural zinc sites from a random peptide library

亜鉛(II)イオンは2 - 3個のアミノ酸残基に結合し，タンパク質の構造を安定化させたり，酵素の活性中心を形成することができる．タンパク質中の亜鉛(II)イオンの結合サイトを同定するために，ファージディスプレイ法を用いて，亜鉛(II)イオンと12量体のランダムペプチドとの結合特異性の探索を行った．2つのアミノ酸配列が明らかにされ，これらは天然に存在する亜鉛(II)含有酵素やフェレドキシンの部分的なアミノ酸配列と一致することがわかった．