Proteins at Interfaces
A few years ago, the development of a protein coating on surfaces of flat polymeric materials or curved nanomaterials was known but not well understood. Since then, the MPI for Polymer Research has set out to acquire a deep understanding of how such a protein coat is formed around polymeric (nano)materials and what are the proteins that are decisive for the biological fate. Besides this we have explored ways to design protein repellent (“stealth”) surfaces with low unspecific protein adsorption or even superamphiphobic surfaces where no protein adsorption was detected within hours. Where protein adsorption cannot easily be avoided we can achieve specific nanomaterial properties by exploiting the characteristics of the proteins adsorbed.
The newly formed interface of proteins on polymeric materials is believed to be the key factor that determines any further interactions with bacteria and mammalian cells. It also influences physicochemical features like aggregation and degradation. To establish routine protocols for the characterization of different nanocarriers in biological media, the effect of different sample preparation methods on the obtained information has to be investigated. We are interested to use a combination of different techniques and preparation methods that can yield much more information than what can usually be obtained by applying them individually. Characterizing the protein adsorption in situ with techniques like dynamic light scattering, isothermal titration calorimetry, quartz crystal microbalance or sum frequency generation spectroscopy allows analyzing all bound proteins including the ones with a very low binding affinity. For other methods such as gel electrophoresis and mass spectrometry a preparation step for protein removal is required which also leads to the removal of weakly bound proteins.