Quantification of biomolecule agglutination by magnetorelaxometry

The agglutination of probes, i.e., biomolecules labeled by magnetic nanoparticles, due to their binding to complement analyte molecules (e.g., biomolecules) was quantified by magneto relaxometry in terms of the mean and the width of the size distribution of the formed aggregates. We observed a clear maximum of the agglutination at a specific analyte-to-probe concentration ratio. By means of controlled variation of this ratio, the concentration of an analyte in solution can be measured in turbid media by two step preparation using magnetic measurement techniques without the need of a solid phase for immobilization of analyte or probe.