Chemical sensors using Langmuir-Blodgett (LB) films have been reviewed. After chemical sensors are classified according to the types of transducing devices and the kinds of analytes in gas or liquid, the sensors with LB films already reported are described. Subsequently, gas sensors, biosensors, and odor sensors are discussed on their materials, deposition conditions and resultant characteristics, etc. The detailed descriptions have been given to the glucose sensors with glucose-oxidaseimmobilized LB films, and it is demonstrated that partially decoiled enzyme molecules can be more efficiently and stably adsorbed onto the monolayer, and more suitable for biosensor fabrication than non-denatured molecules.

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From 1980, various kinds of biosensors based on ion sensitive field effect transistors (ISFETs) were developed. The key technology of the semiconductor biosensor is the precisely controlled miniatualized enzyme-immobilized membrane fabrication technology. To realize a first single chip biosensor based on an ISFET, Ultra-Violet irradiation method was developed in 1984 at the authors laboratory. Two additional methods of immobilized-enzyme membrane were developed in the laboratory. To realize a miniatualized multi-enzyme sensor, an ink jet nozzle method was adapted as a tool of enzyme supply. The most advantage method to fabricate a small enzyme-immobilized membrane is a lite off method which is one of the photo-lithography method, so that the wafer level enzyme-immobilized membrane fabrication method was become to be easy. In this paper, above various enzyme-immobilized methods were reviewed.

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The rapid and simple preliminary screening for toxic compounds was performed electrochemically by using the immobilized tissue sensor composed of an electrode system and a membrane filter-retaining living Chang Liver cells. Two type of sensor systems were developed as follows, The principle of toxicity detection in the first type is based on measuring the respiratory activity. The second type is based on measuring the cells' enzyme activity. In these sensor systems, the current increase was correlated with toxic activity. The sensor systems were applied to the detection of toxicity such as formalin, surfactants and food additives.

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Bioelectrochemical devices are expected to function as biosensors and biocatalytic electrode in biomedical field including artificial organs and cells. In order to design those devices, we have studied electron transfer between the electrode and redox protein such as cytochrome c. Horse heart cytochrome c was immobilized on In₂O₃/SnO₂electrode whose surface was coated with poly-glutamic acid derivatives. That polymer forms a gelated polyanion membrane in the aqueous solution. Thereby the redox reaction of cytochrome c could be successfully controlled.
Since several electrochemical properties of cytochrome c-immobilized electrode were closely dependent on ionic strength, it was suggested that the interaction of cytochrome c molecules with polyanion gel was supported by electrostatically attractive force. In this study, the coupling reaction of the cytochrome c-immobilized electrode with oxidoreductase, e. g. cytochrome oxidase and diaphorase were also examined.
Reduction current of cytochrome oxidase on cytochrome c-immobilized ITO electrode was measured in-0.2Vvs.SCE. The current corresponds to continuous reduction of oxygen in solution and cytochrome c molecules are rapidly reduced at that potential. It was indicated that apparent cathodic currents of cytochrome c decreased with ionic strength, however that cathodic current per molecule increased with ionic strength. Moreover the electron transfer activity of an immobilized cytochrome c molecule closely correlated to apparent diffusion constant of the electron (Dapp). On the other hand immobilized cytochrome c could also react with diaphorase which is classified to NADH dehydrogenase. As the redox reaction of immobilized cytochrome c could be regulated by the electrode potential, it is thought that electrochemical NADH oxidation result from mediation of immobilized cytochrome c.

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Two types of charged porous membranes called CMN and CMA were obtained by co-polymerization of styrene and divinylbenzene. CMN membranes were prepared by using nitrilrubber which has high performance of acid resistance, and also CMA by using acrylicrubber which has no acid resistance. CMA membranes were more porous than CMN membranes. Amino acid could permeate through CMA and CMN membranes. CMN membrane had good performance of electrophoretic separation of amino acids from mixture solution, comparing with CMA membrane. Egg albumin could not pass through CMN and commercially available ion exchange membranes but permeated through CMA membrane. Separation seems to depend on a poresize of the membrane. The suitable pore size of permeation by electrophoresis of egg albumin was estimated to be 0.05 gm using many types of commercially available non-charged micro porous membranes. The pore size of CMA membrane seems to be bigger than 0.05 gm.

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Vapor permeation (VaP) using cellophane membrane was compared with pervaporation (PV) for ethanol-water mixtures under isothermal conditions (Mode I). The selectivity of VaP was higher than that of PV through whole feed composition, while the permeation rate of VaP was lower than that of PV. It was observed that the membrane in PV was more swollen than in VaP.
In the case (Mode II) which feed vapor was superheated in VaP under keeping downstream pressure constant, the selectivity increased remarkably and the permeation rate decreased. In another case (Mode III) which downstream temperature near the membrane was dropped and the temperature gradient was generated through the membrane in VaP, the permeation rate increased and the selectivity decreased.
The influence of temperature to the permeation rate could be expressed by the Arrhenius' correlation only for Mode I. With regard to the influence of downstream pressure, the selectivity of Mode II showed only a slight decrease with downstream pressure, not so much decrease as the usual condition (Mode I).

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By use with high concentration of glucoamylase (0.5 RAG/ml), saccharification time could be reduced by one-tenth compared with that of the production field using enzyme unit of 0.1 RAG/m/. Glucose purity of reaction mixture was accomplished over 98%. Furthermore, coloring of the products was scarcely observed. Used enzyme could be recovered by a semi-batch membrane reactor with polysulfone hollow fiber whose molecular cut off was 5000.
Glucoamylase was denaturated in saccharification reaction to the extent of ca. 30% of initial enzyme dosage. This denaturation was prevented by the addition of hydrophilic polymers, chytosan and polyvinylalcohol. In the case of chytosan, when the final concentration was 600 ppm, the rate of denaturation was 15%. These results showed feasibility of the semi-batch membrane reactor in saccharification process.
In the recovery of the enzyme by membrane, volume flux (l/m²·h) was reduced caused by gel formation on the membrane surface. However, the flux could be recovered by increasing the flow rate. Decrease of the flux with time due to fouling of membrane was suppressed by protection of the hydrophobic group by treatment with chytosan and polyvinylalcohol.

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The evidence that will give us direct information about the amount, the time course and the topology of the intracellular Ca²⁺concentration has been required in order to permit the analysis of the role of the ion inside the cell. Many methods have been introduced to measure the concentration of free Ca²⁺in living cells. Among such methods, fura-2 fluorometry appears to be the most ideal, since the fluorescent probe can be loaded into the intracellular space without attendant injury to the target cells, and furthermore it possesses sufficient sensitivity to permit the measurement of free Ca²⁺levels in the cell. We established a system for the quantitative measurement of the cytosolic Ca²⁺concentration using a fluorescent microscope-video camera system with a frame memory and a computer system. We applied this method to single cultured hippocampal neuron and also hippocampal slice preparation to measure the change in the concentration of Ca²⁺during long term potentiation after tetanic stimulation and also during the exposure to hypoxic and glucose-free medium.

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Activity of the cardiac L-type Ca channels is regulated by extracellular signals such as β-adrenoceptor agonists, and phosphorylation hypothesis has been proposed for the mechanism of channel regulation. This hypothesis was assessed in single myocytes using the voltage-clamp and cell-dialysis methods. Internally applied cyclic AMP (cA MP) or A kinase mimicked the increasing effects of isoproterenol (ISO) on Ca current. Protein kinase inhibitor or protein phosphatases (type 1 and 2A) reversed ISO-enhanced Ca current to control levels. Incubation of Ca channels, which were reconstituted into liposomes, with A kinase increased the dihydropyridine-sensitive Ca efflux from liposomes, suggesting that phosphorylation of the Ca channel or a protein closely associated with the channel is responsible for the channel regulation.
Acetylcholine (ACh) suppressed ISO-enhanced Ca current but not cAMP-or A kinase-enhanced Ca current suggesting that ACh acts at the level before action of cAMP, probably at adenylate cyclase. Consistently, the effect of ACh was abolished by pretreatment of the cells with pertussis toxin.
It is concluded that phosphorylation of a membrane protein is a key mechanism for the regulation of the cardiac Ca channels by extracellular signals.

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