[Biofilms] Re: Surface energy - meaning?

Dev via biofilms%40net.bio.net (by microbesinaction At gmail.com)
Fri Dec 1 01:33:15 EST 2006


Surface energy is a measure of disruption of chemical bonds that occurs
when a surface is created. Most of the hydrophobic surfaces are known
to show low surface energy values. It is also well known that
hydrophobicity has a role in cell attachment to the surface and biofilm
formation. As the biofilm progresses the adhesion is higher and
chemical bonding is more hence lower the surface energy.

Few studies were carried out on adhesion of biological systems such as
proteins, microbes, algae and invertebrates. They all show minimal
long-term adhesion associated with surfaces having low energy surfaces.
However, all surfaces rapidly become modified on immersion in natural
waters through the adsorption of conditioning films, which may
influence subsequent adhesive events associated with the permanent
attachment of organisms. The results show that surface energy can
elicit different responses in different organisms. For most organisms,
minimal adhesion is associated with low surface energy.

According to thermodynamics, matter seeks to be in a low-energy state,
and bonding reduces chemical energy. Young's Modulus says, if the
surface is hydrophobic then the contact angle of a drop of water will
be larger. Hydrophilicity is indicated by smaller contact angles and
higher surface energy. Water has high surface energy by nature; it's
polar and forms hydrogen bonds. Hydrophilicity is generally indicated
by smaller contact angles and higher surface energy. Water has high
surface energy by nature; it's polar and forms hydrogen bonds.

Also check : The influence of low surface energy materials on
bioadhesion : a review by Callow M.E.and Fletcher R. L. Int.
biodeterior. biodegrad. International symposium on marine biofouling
and corrosion, Portsmouth, ROYAUME-UNI. 1994, vol. 34, 3-4, pp. 201-412

Best Regards,

Devendra Dusane
--------------------------------------------
Junior Research Fellow,
University of Pune-Bhabha Atomic Research Centre (BARC) programme
Institute of Bioinformatics & Biotechnology (IBB)
University of Pune
Ganeshkhind, Pune-411 007
India
---------------------------------------------
URL: http://devendradusane.tripod.com
email: microbesinaction At yahoo.co.in
       devendra At unipune.ernet.in
----------------------------------------------

On Nov 30, 2:18 pm, John Brooks <brook... At hkucc.hku.hk> wrote:
> Have a look at Wendy C. Duncan-Hewitt's paper "Nature of the hydrophobic
> effect" in Microbial Cell Surface Hydrophobicity, Doyle, R.J. &
> Rosenberg, M. (Eds).  1990 Am. Soc. Microbiol.
>
> It's not easy going, but explained a lot for me.
>
> Regards
> John
>
> Alfred Ogola Okello wrote:
> > Dear Sir,
>
> > Ref:http://www.bio.net/bionet/mm/biofilms/1998-September/000364.html
>
> > I am having trouble understanding the concept of surface energy (SE).
> > SE seems to mean the same thing as bonding potentiel.
> > What confuses me is that while hydrophobicity increases as SE
> > decreases, adhesion seems to increases. Why does adhesion increase
> > when the bonding potentiel (SE)decreases. I thought that the trend
> > should be the reverse. Moreover, I think that it contradicts the
> > hydrophobicity theory: adhesion of water decreases as the SE decreases.
>
> > Please make it clear for me; maybe I am missing out on something.
>
> > Best regards,
>
> > Alfred
>
> > ------------------------------------------------------------------------
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>
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> 
>  brooksjd.vcf
> 1KDownload



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