From owner-biophysics@net.bio.net Mon Aug 17 23:00:00 1998 Path: biosci!agate!newsfeed.berkeley.edu!news.maxwell.syr.edu!nntp.news.xara.net!xara.net!server6.netnews.ja.net!server4.netnews.ja.net!server2.netnews.ja.net!pegasus.csx.cam.ac.uk!not-for-mail From: Yu Wai Chen Newsgroups: bionet.biophysics Subject: Re: Surface Plasmon Resonance Date: Tue, 18 Aug 1998 14:25:25 +0100 Organization: MRC Centre for Protein Engineering Lines: 33 Message-ID: <35D980C4.85BC3FFD@mrc-lmb.cam.ac.uk> References: <35CB56FD.CAEE4D49@gwdg.de> NNTP-Posting-Host: i11.mrc-lmb.cam.ac.uk Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Mailer: Mozilla 4.05 [en] (X11; I; IRIX64 6.2 IP28) > Can anyone here explain me in short words the principles of Surface > Plasmon Resonance? I'm, a biologist working with proteins and DNA on a > BIAcore, and I've to admit I haven't understood the principles of the > phenomena. So maybe you can give me a quick introduction - only to know > what happens in this black box machine ... ;-) When light enters from one face of a prism it usually get diffracted into a rainbow when it leaves the prism. However, when the incident angle is at a "critical angle", most of the light will get reflected rather than diffracted before it exits the prism. This is "total internal reflection". SPR exploits this physical phenomenone. Now people found that the critical angle changes if we modified the nature of the air/prism interface at where the total internal reflection occurs. Put it simpler, if you, say, paint a coat to the prism, this coat of paint will alter the critical angle. In BIACORE, the machine detects changes in the critical angle in response to the changes (increase) in the nature of the material at the prism/liquid interface. When you imobilise, say an antigenic protein onto the prism, the molecular mass increases and you detect an increase in signal. When you next let an antibody binds to the immobilised antigen, the prism/liquid interface contains yet more mass and further give rise to a higher signal. End of story. Wai -- =================================================================== Yu Wai CHEN, Ph.D. .................. email: ywc@mrc-lmb.cam.ac.uk Centre for Protein Engineering, tel: 44-(1223) 402148 MRC Centre, Cambridge CB2 2QH, U.K. fax: 44-(1223) 402140 WWW homepage: http://www.mrc-cpe.cam.ac.uk/people/wai.html .