Biobased Polymer Coating Using Catechol Derivative Urushiol.

We have investigated the mechanism of the superior mechanical robustness of coated thin films of the catechol derivative urushiol. We synthesized hydrogenated urushiol (h-urushiol) by hydrogenating the double bonds in the long alkyl side chain of urushiol, and the physical properties of thin films of mixtures of urushiol and h-urushiol were evaluated. Atomic force microscopy observations revealed that these coated thin films have a homogeneous surface with no phase separation, regardless of the h-urushiol content, arising from the similarity of the chemical structures.

Scaffold for growing dense polymer brushes from a versatile substrate.

We have demonstrated a universal approach to growing polymer brushes from various substrates. Urushiol was mixed with initiator-containing catechol, and it was spin-coated or cast on various substrates. Because urushiol is strongly adhered to various substrates, the thin film can serve as a general scaffold for grafting polymer brushes from various substrates.

Light-Triggered Adhesion of Water-Soluble Polymers with a Caged Catechol Group.

An acrylamide-type copolymer containing hydroxyl, amino, and -nitrobenzyl protected catechol groups was synthesized as a functional mussel adhesive protein (MAP) mimetic. The resulting copolymer was stable even in the oxidative condition. Light irradiation to aqueous solution of the copolymer induced deprotection of a caged compound to give a native catechol group and triggered an oxidative cross-linking reaction to afford the adhesive gel.

Competition between Oxidation and Coordination in Cross-Linking of Polystyrene Copolymer Containing Catechol Groups.

In gelation chemistry, catechol groups are used as cross-linking points. Both oxidation and coordination effects of catechol were investigated for their unique features in chemistry by spectroscopic measurements. Polystyrene copolymers containing catechol groups were synthesized by free radical copolymerization of styrene and -2-(3',4'-ditriethylsilyloxyphenyl)ethyl methacrylamide, and the successive deprotection reaction was catalyzed by tetra--butylammonium fluoride.

Convenient modular method for affinity labeling (MoAL method) based on a catalytic amidation.

A modular methodology for affinity labeling, in which three essential elements generally constituting affinity probes are prepared separately as individual molecules, has been developed based on a catalytic amidation.

Spontaneous membrane fusion induced by chemical formation of ceramides in a lipid bilayer.

Mere chemical generation of ceramide and related double-chain lipids in the membrane of small unilamellar vesicles (SUVs) induces fusion of the vesicles. The lipids can be successfully prepared by dehydrocondensation between single-chain lipids (fatty acids and sphingosine or its analogues) in a lipid bilayer of the SUV by using a combination of 2-chloro-4,6-dimethoxy-1,3,5-triazine and amphiphilic tertiary amine catalysts, a process that can be compared to a successive enzyme model system for a fatty acyl-CoA synthetase followed by acyltransferase. The SUV spontaneously undergoes membrane fusion upon this internal chemical stimulation by the artificial enzyme system.

Mixing behavior of fluorinated and hydrogenated gemini surfactants at the air-water interface.

Mixing behavior of hydrogenated and fluorinated cationic gemini surfactants was studied at the air-water interface by Brewster angle microscopy and pi-A isotherm curves. In the bulk, these two molecules did not mix and showed phase separation. At the air-water interface, if a monolayer was formed by separate deposition of the two solutions, they formed separate domains, and the compression occurred in two steps: first the domains with hydrogenated gemini surfactant were compressed until they showed collapse; then the domains with fluorinated gemini surfactant were compressed.

Design of novel biointerfaces (II). Fabrication of self-organized porous polymer film with highly uniform pores.

Application of porous polymer materials to novel bio-interfaces for tissue engineering scaffold and artificial organs including blood filters, dialyzer, and oxygenator membranes have been in progress. The present study describes the fabrication and characterization of self-organized highly regular porous polymer films with uniform pore sizes are prepared by simple casting technique. Various fabrication parameters affecting the pore size such as polymer concentration, boiling point of solvent, cast volume and substrate are studied.