2015/7/131 Microsystems for UV-Visible and X-Ray Analysis of Protein Crystals Advisor : Cheng-Hsien Liu Report : Ming-Ju Lee Date : 2007/06/06 L.S.L. Cheung 1, R. Quick 1, S.K. Singh 2, A. Weichsel 2, W.R. Montfort 2 and Y. Zohar 1 1 Dept. of Aerospace and Mechanical Engineering, 2 Dept. of Biochemistry and Biophysics University of Arizona, Tucson, AZ, USA, p.569~572, MEMS2007

2015/7/132 Outline   Introduction   Transmittance test   Device design and fabrication   UV-visible and X-ray analysis   Conclusions

2015/7/133 Introduction   Microfluidic devices have been shown tremendous advantage of miniaturization for performing analysis tasks   Understanding protein crystal structure is paramount in disease therapy and new drug discovery. To this end, UV- visible spectroscopy and X-ray crystallography are the main research methods   However, the powerful measurement technique of X-ray diffraction for elemental analysis and structure determination in fluidic microsystems

2015/7/134 Transmittance Test T r : transmittance factor I o : incident intensity I : emerging intensity μ: material absorption coefficient x : distance inside matter UV-Visible light transmittance factorX-ray transmittance factor

2015/7/135 Conceptual Design  PDMS-based microsystem for UV-visible and X-ray analysis of protein crystals has been design to meet:  Minimum total optical path, less than 100 μ m  Integration of micro- channels for continuous flow of buffer solutions around the crystal  Sufficient device rigidity for stable operation

2015/7/136 Device Fabrication and Packaging Schematic cross-sections of the major steps in fabricating the protein-crystal microsystem

2015/7/137 UV-Visible Light Spectra  UV-visible spectra, provide important information on the or serve as an auxiliary support for  UV-visible spectra, provide important information on the protein catalytic cycle or serve as an auxiliary support for crystal-structure modelling Energy absorbance

2015/7/138 X-Ray Diffraction Analysis  It is the most popular experimental method to determine  It is the most popular experimental method to determine protein structure  A successful protein-crystal microsystem should allow of X-ray radiation with  A successful protein-crystal microsystem should allow high transmittance of X-ray radiation with minimum energy absorbance by the substrate (a)with PDMS, (b) w/o PDMS (c) with glass, and (d) w/o glass

2015/7/139 Conclusions  With a thin PDMS, about 100μ  With a thin PDMS, about 100μm in thickness, both the UV- visible spectrum and the intensity of the X-ray diffraction pattern are almost identical to the protein crystal alone   Microsystems integrated with microchannels allowing continuous exchanges of buffer solution around the protein crystals; this would greatly enhance the potential to induce, trap and characterize functional states in proteins

2015/7/1310 Thanks for your listening !!