Bacteriophages as Factories for Eu2O3 Nanoparticle Synthesis.

The use of phage display to identify peptides with an ability to bind and synthesize Eu2O3 nanoparticles is demonstrated in this report. This is the first report of modified phages specifically binding a lanthanide. The peptides exposed on virions revealed very strong binding to Eu2O3 nanoparticles and the ability to catalyze Eu2O3 nanoparticles' formation from Eu(OH)3 and Eu(NO3)3 solutions. The luminescence emission spectrum of Eu3+ ions indicated that these ions existed mostly in sites deviated from the inversion symmetry in crystalline Eu2O3 aggregates and gelatinous Eu(OH)3 precipitate. The ability of phage-displayed peptides to catalyze formation of Eu2O3 nanoparticles provides a useful tool for a low-cost and effective synthesis of lanthanide nanoparticles, which serve as attractive biomedical sensors or fluorescent labels, among their other applications.