Studying Peptide-Particle interactions via immobilized peptides to develop modern recycling techniques

The Junior Research Group BioKollekt works on the development of novel peptide-based separation processes for the recycling of strategically important metals. In earlier studies, peptides with high selectivity and affinity for particles of the fluorescent powders LaPO4:Ce,Tb and CeMgAl11O19:Tb were identified using phage surface display (PSD). Nonetheless, phages are no option to be a peptide carrier in a classical industry applied separation process. However, the transitioning from phage bound peptides to free peptides proved challenging. Since most analytics are developed mainly for solution phase-chemistry, they are not fully applicable to work with fast sedimenting particles and/or within the used concentration range.
The focus of this study is the introduction of a method for testing and comparing particle-binding peptides by immobilization on glass supports. While the method itself is not dependent on fluorescence, exploiting the fluorescent properties of the target materials, as shown in Fig. 1, enables selective fluorescent scanning methods. This method, in general, allows analyzing and visualizing trends in binding efficiency, affinity and selectivity. It also helps to identify structures relevant for binding. Achieved by varying the peptide sequence this method furthermore enables relatively fast screening routines for key factors like peptide concentrations, elution methods and evaluation of binding capacities. Another part of this study is the evaluation of suitable peptide carriers for further transitioning to a working separation process. Suitable carriers under investigation are (nanocrystalline) celluloses and functionalized glass supports in various geometries. However, our current focus are superparamagnetic iron oxide nanoparticles with a bifunctional and therefore fine-tunable amphiphilic surface coating. Their unique behaviour, cheap and easy synthesis and possible recyclability during the process highlighting them as a promising type of carrier. The rather easy adjustment of the polarity to the needs of the separation process can furthermore enhance peptide-particle interactions in terms of selectivity and accessibility. While the research is still ongoing, preliminary results show promising behaviour and flexibility of the chosen systems.