Low-cost and non-toxic iron oxide nanoparticles can be used for the magnetic purification of peptides and proteins. Even bare iron oxide nanoparticles can be handled easily in molecular recognition and thus purification of peptide sequences in complex suspensions such as cell lysates. In complex liquors such as bodily fluids or cytosol, a protein corona forms around the nanoparticles which defines their new surface “identity”. This complexity of different interactions at the nanoparticle water interface, which is based on molecules and ions, challenges the characterization of nanoparticles and thus their use for multiple applications.

We are able to use the particle identity for protein purifications by using designed peptide tags fused to proteins. The transfer of peptide binding and release at a protein corona forming in cell lysates to the use of a corona in the cytosol of microbial organisms is our main goal. Iron oxide nanoparticles are able to penetrate the cell wall of microorganisms and the stress leads to a pH shift within the cells. This pH shift can be used to release cationic antimicrobial peptides in the cytosol and lead to cell death. Our project combines two different worlds: drug delivery and downstream processing. We essentially strive to learn from each other and make use of our respective expertise in each other’s field of application.

We work together to achieve two goals: To find new and efficient drug delivery systems for existing antimicrobial peptide-based drugs and to improve the capture and release of peptide-based tags for protein purification.