用于晶体生长的地基无容器悬浮技术

空间微重力环境下几乎无对流和沉降,可为晶体生长提供一个相对稳定和均一的理想环境,易于得到尺寸较大的高质量单晶。但是,空间结晶实验成功率低,费用昂贵,实验机会受限。因此,研发各种空间微重力环境地基模拟技术具有重要意义。目前可用于晶体生长的地基无容器悬浮技术主要有空气动力悬浮、静电悬浮、电磁悬浮、液体界面悬浮、超声悬浮和磁场悬浮技术等。这些地基模拟技术可实现晶体的无容器悬浮生长,避免器壁对晶体生长的不良影响,提高晶体质量,为解决X射线单晶衍射技术中的瓶颈问题提供新途径,还可为在地基进行结晶动力学和机理研究提供简单易行的方法。从技术原理、优势、缺陷及在结晶(特别是蛋白质结晶)中的应用4个方面对这些技术逐一进行了介绍和评述。重点介绍了液体界面悬浮、超声悬浮和磁场悬浮技术这3种用于蛋白质晶体生长的较为成熟的地基无容器悬浮技术。

Ground-based Containerless Levitation Techniques for Crystal Growth

The microgravity provides a relatively homogeneous and stable environment for crystallization since the natural convection and sedimentation can be eliminated.Single crystals of larger size and higher diffraction resolution can be therefore obtained in such environment.However,there are limited chances for utilizing space conditions for crystallization because of the low success rate and high cost.As a result,it is necessary to develop ground-based simulation techniques.Presently ground-based levitation techniques include mainly aerodynamic,electrostatic,electromagnetic,liquid interface,ultrasonic and magnetic levitation techniques.Crystallization in containerless levitation condition can be realized using these techniques,through which unfavorable effects on crystallization from the vessel wall can be avoided.As a result,high quality crystals can be obtained,which provides a new solution to deal with that bottleneck problem in X-ray diffraction technique and a convenient means to investigate dynamics and mechanism of crystallization on the ground.Six ground-based levitation techniques are reviewed from the following four aspects: the principle,the advantages,the disadvantages,as well as the applications in crystal growth,especially protein crystallization.Three well-developed levitation techniques(liquid interface,ultrasonic,and magnetic levitation techniques) are high lighted specifically on their applications in protein crystallization.