Publikationsrepositorium - Helmholtz-Zentrum Dresden-Rossendorf

Recycling of rare earth components from fluorescent phosphors of fluorescent light bulbs is focussed in the MinePep project. The current recycling rate of rare earths in spent electronic devices is less than 1%, partly due to the similar chemical and physical properties of the elements making their separation difficult. New recycling strategies needs to focus on effective and ecofriendly processes for the recovery of critical elements within such spent electronic devices. Beside the relevance for the environment, new products and techniques need to be highly-specific for target materials and be economically viable.
The identification of highly-specific bio-collector peptides for special fluorescent phosphors was successful by using phage surface display. This technique uses a phage library with a diversity of 109 different peptide expressing phage clones, where each clone expresses a different peptide sequence on one of the phage surface proteins. In affinity binding screens, the target was exposed to the phage library. Phage with a low target affinity were removed while strong binders were amplified and analyzed for their individual binding characteristics. Final goal of this approach is the application of the isolated peptides as bio-collectors in bio-flotation systems.
The fluorescent phosphors LaPO4:Ce,Tb and CeMgAl11O19:Tb were individually exposed to a phage library and highly-specific peptide expressing phage clones were identified and characterized. The amino acid compositions and the target material affinities differ significantly between the identified sequences. Phage specifically bound to the target were visualized by using phage-specific antibodies. A high number of specifically-bound phage was detected. The binding specificities of individual peptides were improved by substitution of individual amino acids within the peptide sequence.
In summary, phage surface display is a promising tool for the development of highly-specific binding peptides. The development of ecofriendly and specific collectors for use in bio-flotation and separation processes has the potential to revolutionize traditional recycling techniques.