This review article describes fundamental aspects of cell membrane-inspired phospholipid polymers involving nonfouling phenomena and their usefulness in the development of medical devices. Since the early 1990s, polymers composed of 2-methacryloyloxyethyl phosphorylcholine (MPC) units have been considered in the preparation of biomaterials. MPC polymers can provide an artificial cell membrane structure at the surface and serve as excellent biointerfaces between artificial and biological systems. They have also been applied for the surface modification of some medical devices including long-term implantable artificial organs. An MPC polymer biointerface can suppress unfavorable biological reactions such as protein adsorption and cell adhesion. In other words, specific biomolecules immobilized on an MPC polymer surface retain their original functions. Regarding the properties as a biointerface with an artificial cell membrane structure, the use of MPC polymers has grown worldwide for creating desired biointerfacial phenomena on artificial materials.

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Proteins often adsorb tightly to metal surfaces. Such a tight adsorption of protein leads to fouling of the wall surface of manufacturing equipment in food and drug manufacturing processes. The author has been engaged in the study of the adsorption behavior and mechanism of protein to metal (oxide) surfaces and the development of cleaning techniques that can remove adsorbed protein absolutely from metal surfaces under mild conditions. The results of the investigation to date have revealed that the electrostatic interactions via acidic amino acid residues of protein largely contribute to the tight adsorption. As for cleaning technique, a novel one that involves the use of hydroxyl radicals (・OH) generated by the electrolysis of hydrogen peroxide(H₂O₂-electrolysis cleaning) has been developed. It was demonstrated that the irreversibly-adsorbed proteins on metal (oxide) surfaces (stainless steel, titanium, and etc.) could be absolutely removed within a few minutes by the H₂O₂-electrolysis treatment at room temperature. The influences of various treatment factors on the removal behavior in H₂O₂-electrolysis cleaning were investigated.

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Microorganisms tend to form biofilms on biotic and/or abiotic surfaces, which is a com plicated process consisting of two phases: an initial adhesion phase and the subsequent biofilm development phase. Many kinds of bacteria have filamentous cell appendages, which are several to tens nanometers in diameter, such as flagella and pili. These bacterionanofibers have been shown to function as adhesins. We have been studying the mechanisms of microbial adhesion and biofilm formation and their application to bioprocesses. In this article, our recent results are briefly reviewed with future direction of the study. In application of biofilms to waste water treatment, three successful examples are introduced; they are construction of functional biofilms for oil degradation as a new concept of “bottom-up biofilms”, biological prevention of biofouling in membrane bioreactors, and the mechanism of high capacity of carbon fiber for adsorbing sludge and microorganisms. In the topic about bacterionanofibers, a new fibrous adhesin designated AtaA from the highly adhesive bacterium Acinetobacter sp. Tol 5 is introduced in terms of its structure and function. It can be utilized to direct immobilization of microbial cells. An example of production of a chemical using the immobilized cells is demonstrated.

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Recently, analytical method of glycidyl fatty acid esters (GE) has been developed extensively in Japan, the United States and the European Union. In 2010, direct method to quantify GE in edible oil by using LC-MS was reported in Japan. After some modifications were made, AOCS and JOCS initiated joint collaborative study (24 organizations in nine countries) in 2011 in order to evaluate the accuracy, the reproducibility and the simplicity of the method. Since the collaborative study provided acceptable results, the direct method of GE was registered as joint AOCS/JOCS official method.

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