Study On Optical Observation Technology Of Mass Transfer Process During Protein Crystal Growth

There is no natural convection under the microgravity condition in space which benefit the growing of protein crystals.It is of great significance for the optimization of the artistic process of protein crystallization by observing the crystal morphology and material transport process of the crystal growth process in space.However,scientific experiments in space require fully developed technology.Both the schlieren and phase contrast microscopy method with multi-function and integration devices are adopted.A straight-type schlieren system should be designed for the development of principle prototype for the integrated method of phase contrast and phase contrast microscopy,although the Z-type optical path layout system is usually used in the schlieren method at present.In this thesis,based on the traditional Z-type optical path layout schlieren method,a ground-based demonstration system of the straight-type schlieren method is built,and an optimization design is completed to verify the accuracy of the straight-type schlieren system.In addition,the studies on the growth of protein crystals under simulated microgravity conditions is carried out.Finally,lysozyme crystals in growth in the integrated principle prototype is observed.The main contents and results are as follows:(1)The straight-type schlieren system is bulit.In this thesis,optimization experiments are performed on the light source,lens,knife edge,and receiving screen in the Straight-type schlieren system.Various optimized parameters are obtained,as well as high-resolution schlieren images.(2)The accuracy of the straight-type schlieren system is verified.The model system candle flame is used for research,the flame schlieren image is observed and analyzed quantitatively,and the calculation results are compared with the actual measurement results.The results show that the optimized straight-type schlieren system can measure the flow field accurately.(3)Crystals grow under simulated microgravity conditions.By preparing a polydimethylsiloxane(PDMS)porous membrane,crystal seeds are introduced into a small cavity in the PDMS porous membrane for growth.Due to the small space in the small cavity,natural convection can be weakened or eliminated,so the pure diffusion growth can be achieved,and finally high-quality crystals are obtained.(4)The principle prototype is developed for observing the crystal morphology and concentration distribution around the crystal during the growth of protein crystals.First,because the protein crystals are small and the thickness of the dissipative layer is thin,the Straight-type schlieren system has been partially improved,and it is integrated with the phase-contrast micro-system phase as a principle prototype;the ground-based prototype observation experiment on lysozyme crystals is accomplished,and the lysozyme crystal schlieren image and phase-contrast micrograph are obtained.In this way,high-resolution crystal morphology is observed,and accurate concentration gradient distribution and dissipative layer changes are obtained,which provide a technical basis for future experimental research on spatial microgravity protein crystal growth.