Flow-free droplet-based platform for spiral-striated polymorphic structure of periodical crystalline agglomerates

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The overarching goal of this research is to develop flow-free droplet-based platform for high-throughput and particular crystal structure directly. Crystallization plays an important role in the pharmaceutical manufacturing industry. However, the traditional on-chip approach such as the emulsion-based platform and concentric capillary tube suffers from the limitations including mixed crystal forms, broad size distribution, and incongruous crystal growth. Here, we report a study that generates single type of crystal with a particular contribution of two process parameters, namely, temperature and pH value. With our method, the droplets were formed isolated in each anchor due to surface tension, and the crystals were located as array automatically. We have successfully obtained the single γ form glycine crystal and spherical crystalline agglomerates array. Remarkably, the spiral-striated glycine structure of periodical crystalline agglomerates (PAs), asymmetric crystallization of droplet, crystalline shift, and shock wave expansion of crystallization energy releasing phenomenon were discovered in the first time. The distance, or named period, of inner spiral structure and their curvature radius were determined to identify PAs-2 structure. Moreover, its components and crystal forms are identified as α type by X-ray diffraction analysis as well. In a word, this work provides a flow-free droplet-based platform for advancing the crystallization technology and thus extends the vision of pharmaceutical manufacturing field.

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This work was supported by Complex and Intelligent Research Center, School of Mechanical and Power Engineering, East China University of Science and Technology. The X-ray diffraction analysis was supported by BL16B1 in Shanghai Synchrotron Radiation Facility. The authors would like to thank the financial support of National Natural Science Foundation of China (21404038) and (21375166), 111 Project (D18003), the Fundamental Research Funds for the Central Universities of China (22A201514029), and Natural Science and Engineering Research Council of Canada Discovery Grant (417649).

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Correspondence to Shih-Mo Yang.

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Yang, S., Chen, F., Yin, D. et al. Flow-free droplet-based platform for spiral-striated polymorphic structure of periodical crystalline agglomerates. Microfluid Nanofluid 22, 114 (2018) doi:10.1007/s10404-018-2137-2

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  • Flow free
  • Droplet-based platform
  • Crystallization
  • Glycine
  • Spherical crystalline agglomerates