[RASMB] nanoparticles

[Arthur Rowe]

Hi Louise

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.

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.

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!).

Kind regards

Arthur

*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).


--
*******************************************************
Arthur J Rowe
Professor of Biomolecular Technology
NCMH Business Centre
University of Nottingham
School of Biosciences
Sutton Bonington
Leicestershire LE12 5RD   UK

Tel:        +44 (0)115 951 6156
           +44 (0)116 271 4502
Fax:        +44 (0)115 951 6157
email:      arthur.rowe at nottingham.ac.uk
Web:        www.nottingham.ac.uk/ncmh/business
*******************************************************




Hello,
Does anyone have experience in running samples containing nanoparticles
(30 nm diameter; copper, iron, silver or gold) in aqueous buffer
solutions on the XL-I?
Thank you.
Louise Creagh.
University of British Columbia.

-- 
Louise Creagh


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