Time‐Controlled Microfluidic Seeding in nL‐Volume Droplets To Separate Nucleation and Growth Stages of Protein Crystallization

Sowing seeds: The growth of well-ordered protein crystals requires control of the two key stages of crystallization, namely, nucleation and growth. However, the ideal conditions for these two stages are often different. A microfluidic system (see picture) was used to perform time-controlled crystal seeding in nL volumes. Single crystals of the protein Oligoendopeptidase F were obtained and used to determine its X-ray crystal structure.