Awel Salah, Bohne Sven, Ebrahimifard Reza, Trieu Hoc Khiem, Bajt Saša, Chapman Henry N
Opt Express. 2021 Oct 11;29(21):34394-34410. doi: 10.1364/OE.440173.
High-speed liquid micro-jets are used to rapidly and repeatedly deliver protein microcrystals to focused and pulsed X-ray beams in the method of serial femtosecond crystallography. However, the current continuous flow of crystals is mismatched to the arrival of X-ray pulses, wasting vast amounts of an often rare and precious sample. Here, we introduce a method to address this problem by periodically trapping and releasing crystals in the liquid flow, creating locally concentrated crystal bunches, using an optical trap integrated in the microfluidic supply line. We experimentally demonstrate a 30-fold increase of particle concentration into 10 Hz bunches of 6.4 μm diameter polystyrene particles. Furthermore, using particle trajectory simulations, a comprehensive description of the optical bunching process and parameter space is presented. Adding this compact optofluidics device to existing injection systems would thereby dramatically reduce sample consumption and extend the application of serial crystallography to a greater range of protein crystal systems that cannot be produced in high abundance. Our approach is suitable for other microfluidic systems that require synchronous measurements of flowing objects.
在飞秒级连续晶体学方法中，高速液体微射流用于将蛋白质微晶快速且重复地传送到聚焦的脉冲X射线束中。然而，当前晶体的连续流动与X射线脉冲的到达不匹配，浪费了大量通常稀少且珍贵的样品。在此，我们介绍一种方法来解决这一问题，即通过集成在微流体供应管线中的光阱，在液流中周期性地捕获和释放晶体，从而形成局部浓缩的晶体束。我们通过实验证明，对于直径为6.4μm的聚苯乙烯颗粒，在10Hz的束流中颗粒浓度提高了30倍。此外，通过粒子轨迹模拟，对光学聚束过程和参数空间进行了全面描述。将这种紧凑的光流体装置添加到现有的注射系统中，将显著减少样品消耗，并将连续晶体学的应用扩展到更多无法大量制备的蛋白质晶体系统。我们的方法适用于其他需要对流动物体进行同步测量的微流体系统。
