The Determination of Thickness and Surface Mass Density of Mesothick Immunoprecipitate Layers by Null Ellipsometry and Protein 125Iodine Labeling
✍ Scribed by Johan Benesch; Agneta Askendal; Pentti Tengvall
- Book ID
- 102585774
- Publisher
- Elsevier Science
- Year
- 2002
- Tongue
- English
- Weight
- 160 KB
- Volume
- 249
- Category
- Article
- ISSN
- 0021-9797
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✦ Synopsis
The aim of the present study was to ellipsometrically determine the thickness and surface mass density in air for up to 110-nm-thick organic layers made of alternatingly deposited layers of HSA and polyclonal anti-HSA on hydrophobic silicon. The ellipsometrically determined thickness was compared to that obtained by AFM and the deposited surface mass density calibrated with (125)I-labeled proteins. The results indicate a good agreement in protein layer thickness between AFM and ellipsometry when the protein film refractive index N(film)=1.5-0i, although then the calculated surface mass density from the ellipsometry data became grossly overestimated by the Cuypers one-component formula. A good agreement in the surface mass density was obtained when the M/A ratio in this formula was lowered from 4.14 to 2.35. This approach indicates a convenient means of determining the refractive indices and surface mass densities of mesothick organic layers proteins on solid supports.