title: The determination of thickness and surface mass density of mesothick immunoprecipitate layers by null ellipsometry and protein 125iodine labeling.
abstract: 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.
authors.affiliation: Applied Physics, IFM, Linköpings Universitet, Linköping SE-581 83, Sweden.
authors.forename: Johan
authors.initials: J
authors.lastname: Benesch
authors.forename: Agneta
authors.initials: A
authors.lastname: Askendal
authors.forename: Pentti
authors.initials: P
authors.lastname: Tengvall
mesh_terms: D006801:Humans; D047468:Immunoprecipitation / Q000379:methods*; D007455:Iodine / Q000032:analysis / Q000737:chemistry*; D007457:Iodine Radioisotopes; D007553:Isotope Labeling / Q000379:methods*; D012709:Serum Albumin / Q000032:analysis / Q000737:chemistry*
chemical_list: D007457:Iodine Radioisotopes; D012709:Serum Albumin; D007455:Iodine