Bitan:Dynamic Light Scattering

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 <td width=868 valign=top style='width:868.0pt;padding:0in 5.4pt 0in 5.4pt'>
 <p class=MsoNormal align=center style='text-align:center'><span
 style='font-size:16.0pt;color:#993300'><b>Dynamic light scattering <o:p></o:p></b></span></p>
 <p class=MsoNormal align=center style='text-align:center'><span
 style='color:black'><b><![if !supportEmptyParas]>&nbsp;<![endif]><o:p></o:p></b></span></p>
 <p class=MsoNormal><span style='color:black'>Precision Detectors PD2000DLS <o:p></o:p></span></p>
 <p class=MsoNormal><span style='color:black'>Quasielastic light scattering
 (QLS) spectroscopy is an optical method for the determination of diffusion
 coefficients of particles in solution.<o:p></o:p></span></p>
 <p class=MsoNormal><span style='color:black'><![if !supportEmptyParas]>&nbsp;<![endif]><o:p></o:p></span></p>
 <p class=MsoNormal><span style='color:black'><b>Instrumental procedure:<o:p></o:p></b></span></p>
 <p class=MsoNormal><span style='color:black'>1. Switch on computer.<o:p></o:p></span></p>
 <p class=MsoNormal><span style='color:black'>2. Switch on the laser beam
 PDDLS/Batch<o:p></o:p></span></p>
 <p class=MsoNormal><span style='color:black'>3. Switch on detector PD2000DLS.<o:p></o:p></span></p>
 <p class=MsoNormal><span style='color:black'>4. Open PrecisionDeconvolve
 program on the desktop of computer. <o:p></o:p></span></p>
 <p class=MsoNormal><span style='color:black'>5. Parameter setting: <o:p></o:p></span></p>
 <p class=MsoNormal><span style='color:black'>5.1 Sample time&#8211; maintain
 at least 1 photo count per correlation time.<o:p></o:p></span></p>
 <p class=MsoNormal><span style='color:black'>5.2 Run time&#8211;<span
 style="mso-spacerun: yes">&nbsp; </span>intervals between detector
 measurements. Recommend 5-20s.<o:p></o:p></span></p>
 <p class=MsoNormal><span style='color:black'>5.3 Accumulation
 time&#8211;<span style="mso-spacerun: yes">&nbsp; </span>the amount of time
 over which the individual run times are averaged to produce a window with
 your distribution of species. Recommend 4-10.<o:p></o:p></span></p>
 <p class=MsoNormal><span style='color:black'>5.4</span><span
 style='color:black;mso-fareast-language:ZH-CN'> Repeat # &#8211; the number
 of accumulated run times you to repeated. <o:p></o:p></span></p>
 <p class=MsoNormal><span style='color:black;mso-fareast-language:ZH-CN'>5.5
 Cutoff intensities &#8211; the limit that the detector will ignore
 measurements that exceed a certain percentage of the average. Recommend 20%
 of the average. This value can be changed based on the size and relative
 stability of the scattering species.<o:p></o:p></span></p>
 <p class=MsoNormal><span style='color:black;mso-fareast-language:ZH-CN'>6.
 Data is saved under measurement setup/sample record/path. <o:p></o:p></span></p>
 <p class=MsoNormal><span style='color:black;mso-fareast-language:ZH-CN'>7.
 Click GO will start measurements.<o:p></o:p></span></p>
 <p class=MsoNormal><span style='color:black;mso-fareast-language:ZH-CN'>8.
 After the measurements, the data information could be viewed at setup/ data
 record view.<o:p></o:p></span></p>
 <p class=MsoNormal><span style='color:black;mso-fareast-language:ZH-CN'><![if !supportEmptyParas]>&nbsp;<![endif]><o:p></o:p></span></p>
 <p class=MsoNormal><span style='color:black'><b>Sample preparation:<o:p></o:p></b></span></p>
 <p class=MsoNormal><span style='color:black'>1. </span>Dissolve compound in
 required buffer solution.</p>
 <p class=MsoNormal>2. Centrifuge at 5000 g for 30 minutes to remove <span
 style='color:black'>the big undissolved materials or dust.<o:p></o:p></span></p>
 <p class=MsoNormal><span style='color:black'>3. Transfer the CLEAN (dust
 free) solution to Kimble disposable culture glass tubes (6&times;50 mm), which
 is clean and fit to sample holder. <o:p></o:p></span></p>
 <p class=MsoNormal><span style='color:black'>4. Test DLS to see if the
 concentration is enough for recording.<o:p></o:p></span></p>
 <p class=MsoNormal><span style='color:black'><![if !supportEmptyParas]>&nbsp;<![endif]><o:p></o:p></span></p>
 <p class=MsoNormal><span style='color:black'><b>Notes for sample preparation:<o:p></o:p></b></span></p>
 <p class=MsoNormal><span style='color:black'>1. The concentration of the
 sample required for successful measurement is dependent on the size of the
 scattering particles. Since a large particle will scatter more light than a
 smaller particle, a lower concentration will be required. If the
 concentration is too high, multiple scattering can be a problem. In addition,
 inter-particle interactions makes analysis of the results obtained at high
 concentration difficult.<o:p></o:p></span></p>
 <p class=MsoNormal><span style='color:black'>2. It is critical that the
 sample and the cuvette are clean and there is no particulate matter in the
 sample. Dust, undissolved sample, and any extraneous matter will
 significantly affect the accuracy of the results.<o:p></o:p></span></p>
 <p class=MsoNormal><span style='color:black'>3. Except for centrifugation
 method to remove the pre-aggregated protein or dust, filter filtration (20-nm
 pore-size anatop filter) or flow-through filtering (SEC) also could be used.<o:p></o:p></span></p>
 <p class=MsoNormal><span style='color:black'>4. Centrifugation method is less
 effective in removing large flaky particles or linear aggregates.<o:p></o:p></span></p>
 <p class=MsoNormal><span style='color:black'>5. Keep the sample covered at
 all times. This will eliminate the possibility of dust particles from the
 room from entering the sample.<o:p></o:p></span></p>
 <p class=MsoNormal><span style='color:black'>6. Use the highest quality
 solvents available to wash cuvettes if needed (e.g. deionized or distilled
 water). Our tube is disposable tube, which is dust free. You need not wash
 it.<o:p></o:p></span></p>
 <p class=MsoNormal><span style='color:black'>7. After the sample filled in
 the tube and sealed, clean the outside of the tube with lens paper and
 methanol.<o:p></o:p></span></p>
 <p class=MsoNormal><span style='color:black'>8. Hold cuvettes only by the top
 of the cuvette and make sure that you have not deposited any fingerprints on
 the sides of the cuvette. Fingerprints will scatter laser light and create
 scatter signals that are not related to your sample.<o:p></o:p></span></p>
 <p class=MsoNormal><span style='color:black'>9. As you fill the cuvette, take
 care to ensure that no air bubbles are created. Air bubbles will scatter
 light (and may indicate that the cuvette is not clean).<o:p></o:p></span></p>
 <p class=MsoNormal><span style='color:black'><![if !supportEmptyParas]>&nbsp;<![endif]><o:p></o:p></span></p>
 <p class=MsoNormal><span style='color:black'>(The method is modified from Dr.
 Aleksey Lomakin, Dr. Bernhard Monien, and Dr. Ghiam Yamin’s protocols)<o:p></o:p></span></p>
 <p class=MsoNormal><span style='color:black'><![if !supportEmptyParas]>&nbsp;<![endif]><o:p></o:p></span></p>
 <span style='font-size:12.0pt;font-family:"Times New Roman";color:black;
 mso-ansi-language:EN-US;mso-fareast-language:EN-US'><br clear=ALL
 style='page-break-before:always'>
 </span>
 <p class=MsoNormal><span style='color:black'><b>Recommended reading:<o:p></o:p></b></span></p>
 <p class=MsoNormal><span style='color:black'>Aleksey Lomakin, David B.
 Teplow, and George B. Benedek. Quasielastic Light Scattering for Protein
 Assembly Studies. <i>Methods in Molecular Biology, vol. 299: Amyloid
 Proteins: Methods and Protocols. </i></span><span style='color:black'>Edited
 by: E. M. Sigurdsson © Humana Press Inc., Totowa, NJ.<o:p></o:p></span></p>
 <p class=MsoNormal><span style='color:black'>Aleksey Lomakin and David B. Teplow.
 Quasielastic Light Scattering Study of Amyloid b-Protein Fibril Formation. <i>Protein
 &amp; Peptide letters, </i></span><span style='color:black'>2006, 13,
 247&#8211;254.<o:p></o:p></span></p>
 <p class=MsoNormal align=center style='text-align:center'><![if !supportEmptyParas]>&nbsp;<![endif]><span
 style='color:black'><b><o:p></o:p></b></span></p>
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<p class=MsoNormal><b><a href="http://openwetware.org/wiki/Bitan:todo">[Back to Bitan: todo page]</a><o:p></o:p></b></p>

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