Turbidimetric and nephelometric tests* are useful for the quantification of antigen in human or animal biological fluids.
For this application, extremely uniform Estapor® microspheres with different surfaces (plain, COOH, NH2, CH2Cl) and sizes (50-300 nm) are required.
Estapor® microspheres coated with a monoclonal or polyclonal antibodies formed insoluble immuno-complexes when mixed with sample containing the corresponding antigen.
These immuno-complexes cause an absorbance change, dependent upon antigen concentration of the patient sample which can be quantified by comparison from a calibrator of known antigen concentration.
If light is passed through the reaction cuvette, the incoming light is scattered during passage at an angle relative to the optical axis. This angle is function of the size of the complexes and the wavelength of the incoming light (Figure 1).