Surface analysis

Analyte

• Polymers or biomolecules, which adsorb at interfaces or which are bound via specific interactions or covalently. Layer thicknesses in the range of some tenths of nanometres up to several hundred nanometres

Equipment

• Reichert SR 7000 DC double channel instrument with flow system or cuvette

Evaluation methods and targets

• Measurement of local change in refractive index at the sensor surface in real time
• Relative change of the mass loading of a surface
• If refractive index of adsorbed material is known: thickness of the adsorbed layer
• Kinetics of adsorption / interaction

Application examples

• Thickness determination of thin and ultra-thin polymer layers
• Real-time monitoring of the build-up of a polymer layer
• Determination of K_D of an antibody/antigen interaction

Measuring principle

• SPR-principle [PDF]

Comparative and additional methods

• Ellipsometry
• Atomic force microscopy