Determination of the Adhesion Forces of Magnetic Composite Particles

Abstract

The separation of specific proteins from a fermentation broth is a challenge in biotechnology. Problematic impurities are mainly foreign proteins that are present in the fermentation broth and have similar properties to the product. One approach for the specific separation of the target protein is the so-called high gradient magnetic separation (HGMS) with functionalized magnetic particles. The functionalization is specifically adapted to the product, so that ideally only the product binds to the particles. The particles can thus be added directly into the fermentation broth with the product where the product binds to the particles. The particles loaded with the product are then separated from the rest of the fermentation broth in a magnetic separator. A particle fixed bed builds up in the magnetic separator, which must be resuspended after separation from the fermentation broth in order to be able to reuse the particles. For complete resuspension, the separating forces must exceed the adhesive forces between the particles and between the particles and the magnetic matrix. In previous studies of HGMS processes it is assumed that the magnetic force is the dominant one and thus the other forces, e.g. the van der Waals or electrostatic interactions, are negligible. In the investigations carried out so far, the focus has been on the separation of particles in the magnetic filter. However, the resuspension of the particles found little attention. Building on this, the individual interactions between the particles and between the particles and surfaces move into the focus of this work. On the basis of a detailed examination of the interactions at the particulate level, the individual forces were to be quantified and the influencing factors on the forces to be determined.