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<TITLE>Re: [RASMB] nanoparticles</TITLE>
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<BLOCKQUOTE><FONT COLOR="#800000">Hi Louise<BR>
<BR>
You should have no problems. I have run gold particles* (the heaviest of the lot) at 3000 rpm, using absorption optics, and the output is fine. Only thing to note - it is difficult to use c(s) analysis in SEDFIT for a system which is polydisperse (OK - it's size distribution may be uni-modal, but that simply means it is polydisperse about a mean). So you may get nice looking peaks but terrible quality fits with c(s), as treating the frictional ratio as a variable is hardly justifiable, and you tend to get idiotic estimates if you try.<BR>
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However, ls-g(s*) is fine - and for something as big as 30 nm, diffusion will be minimal, so this function may not be too bad an approximation to the 'true' distribution function.<BR>
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The non-gold particles which you mention will be even easier to work with than gold, as they are less dense than gold (whose vbar is around 0.052!).<BR>
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Kind regards<BR>
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Arthur<BR>
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*mine were 15.4 nm diameter, and had an s value of 50S. Yours at 30 nm will have a predicted s value of around 200S - still well within the capacity of the instrument to measure (I have done virus particles of up to 800S).<BR>
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*******************************************************<BR>
Arthur J Rowe<BR>
Professor of Biomolecular Technology<BR>
NCMH Business Centre<BR>
University of Nottingham<BR>
School of Biosciences<BR>
Sutton Bonington<BR>
Leicestershire LE12 5RD UK<BR>
<BR>
Tel: +44 (0)115 951 6156<BR>
+44 (0)116 271 4502<BR>
Fax: +44 (0)115 951 6157<BR>
email: arthur.rowe@nottingham.ac.uk<BR>
Web: www.nottingham.ac.uk/ncmh/business<BR>
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<BLOCKQUOTE><TT>Hello,<BR>
Does anyone have experience in running samples containing nanoparticles <BR>
(30 nm diameter; copper, iron, silver or gold) in aqueous buffer <BR>
solutions on the XL-I?<BR>
Thank you.<BR>
Louise Creagh.<BR>
University of British Columbia.<BR>
<BR>
-- <BR>
Louise Creagh<BR>
<BR>
<BR>
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