title: Controlling protein crystal nucleation by droplet-based microfluidics.
abstract: Herein, we demonstrate the potential of droplet-based microfluidics for controlling protein crystallization and generating single-protein crystals. We estimated the critical droplet size for obtaining a single crystal within a microdroplet and investigated the crystallization of four model proteins to confirm the effect of protein molecular diffusion on crystallization. A single crystal was obtained in microdroplets smaller than the critical size by using droplet-based microfluidics. In the case of thaumatin crystallization, a single thaumatin crystal was obtained in a 200 μm droplet even with high supersaturation. In the case of ferritin crystallization, the nucleation profile of ferritin crystals had a wider distribution than the nucleation profiles of lysozyme, thaumatin, and glucose isomerase crystallization. We found that the droplet-based microfluidic approach was able to control the nucleation of a protein by providing control over the crystallization conditions and the droplet size, and that the diffusion of protein molecules is a significant factor in controlling the nucleation of protein crystals in droplet-based microfluidics.
authors.affiliation: Department of Molecular and Material Sciences, Interdisciplinary Graduate School of Engineering Sciences, Kyushu University, 6-1 Kasuga-Koen, Kasuga, Fukuoka 816-8580 (Japan).
authors.forename: Masatoshi
authors.initials: M
authors.lastname: Maeki
authors.forename: Yuki
authors.initials: Y
authors.lastname: Teshima
authors.forename: Saori
authors.initials: S
authors.lastname: Yoshizuka
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Yamaguchi
authors.forename: Kenichi
authors.initials: K
authors.lastname: Yamashita
authors.forename: Masaya
authors.initials: M
authors.lastname: Miyazaki
mesh_terms: D019747:Aldose-Ketose Isomerases / Q000737:chemistry; D000818:Animals; D002645:Chickens; D003460:Crystallization / Q000295:instrumentation*; D004867:Equipment Design; D005293:Ferritins / Q000737:chemistry; D006736:Horses; D046210:Microfluidic Analytical Techniques / Q000295:instrumentation*; D009113:Muramidase / Q000737:chemistry; D010940:Plant Proteins / Q000737:chemistry; D011506:Proteins / Q000737:chemistry*; D013302:Streptomyces / Q000201:enzymology
chemical_list: D010940:Plant Proteins; D011506:Proteins; C003427:thaumatin protein, plant; D005293:Ferritins; D009113:Muramidase; D019747:Aldose-Ketose Isomerases; C023298:xylose isomerase
keywords: droplet; microfluidics; mononucleation; protein crystallization; single crystallization