[Applied Materials and Interfaces] 3D-Printed High-Density Droplet Array Chip for Miniaturized Prote
Here we describe the combination of three-dimensional (3D) printed chip and automated microfluidic droplet-based screening techniques for achieving massively parallel, nanoliter-scale protein crystallization screening under vapor diffusion mode. We fabricated high density microwell array chips for sitting-drop vapor diffusion crystallization utilizing the advantage of 3D printing technique in producing high-aspect-ratio chips. To overcome the obstacle of 3D printed microchips in performing long-term reactions caused by their porousness and gas permeability properties in chip body, we developed a two-step post processing method, including paraffin filling and parylene coating, to achieve high sealability and stability. We also developed a simple method especially suitable for controlling the vapor diffusion speed of nanoliter-scale droplets, by changing the layer thickness of covering oil. With the above methods, 84 tests of nanoliter-scale protein crystallization under vapor diffusion mode were successfully achieved in the 712 droplet array chip with a protein consumption of 10 nL for each test, which is 20-100 times lower than that in the conventional large-volume screening system. Such a nanoliter-scale vapor diffusion system was applied to two model proteins with commercial precipitants, and displayed advantages over that under microbatch mode. It identified more crystallization conditions, especially for the protein samples with lower concentrations.
Yi-Ran Liang, Li-Na Zhu, Jie Gao, Hong-Xia Zhao, Ying Zhu, Sheng Ye, and Qun Fang ACS Appl. Mater. Interfaces, Just Accepted Manuscript DOI: 10.1021/acsami.6b15933 Publication Date (Web): March 17, 2017 Copyright © 2017 American Chemical Society