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The extractive technique for protein purification based on two-phase separation in aqueous micellar solutions (aqueous micellar two-phase system (AMTPS)) is reviewed. The micellar solution of a nonionic surfactant, such as polyoxyethylene alkyl ether, which is most frequently used for protein extraction, separates into two phases upon heating above its cloud point. The two phases consist of a surfactant-depleted phase (aqueous phase) and a surfactant-rich phase. Hydrophilic proteins are partitioned to the aqueous phase and hydrophobic membrane proteins are extracted into the surfactant-rich phase. Because of the methodological simplicity and rapidity, this technique has become an effective means, and thus has been widely used for the purification and characterization of proteins. In contrast to polyoxyethylene alkyl ether, micellar solutions of a zwitterionic surfactant, such as alkylammoniopropyl sulfate, separate below the critical temperature. Alkylglucosides can also separate into two phases upon adding water-soluble polymers. Recently, these twophase systems have been exploited for protein separation. Additionally, hydrophobic affinity ligands, charged polymers, and ionic surfactants have been successfully used for controlling the extractability of proteins in AMTPS.

The band-gap energy tuning of WO3 quantum dots was realized in the range of 2.6 eV (bulk) to 3.7 eV (sub-nano) by precise size control around one nanometer. Newly synthesized sub-nanoporous silicas act as excellent templates. In addition, single-electron reduction of oxygen under UV irradiation is now achievable with WO3.