Harnessing Rare Earth Elements in Proteins and Functional Materials for Advanced Optical, Magnetic, and Mechanical Applications

Rare earth‐proteins and their functional materials integrate unique physical properties of rare earth ions (RE 3+ ) with structural programmability of proteins, attracting increasing attention in a wide range of applications. Coordination with RE 3+ can enhance the rigidity and stability of certain proteins, even induce secondary structure transitions, and confer distinct physical properties onto functional materials. The programmability of amino acid sequences regulates coordination chemistry between proteins and RE 3+ , enabling the modulation of their optical and magnetic properties. Moreover, RE 3+ incorporation turns protein structures and aggregation state, leading to enhanced mechanical properties and adhesion strength. However, the development of such materials still faces significant challenges due to lack of molecular mechanism analysis and systematic rational design strategies. This review highlights the chemical structural analysis, rational design and synthesis strategies of rare earth‐protein and their functional materials. In addition, their applications in optics, magnetics, and mechanics are summarized. Finally, their current challenges and future perspectives are discussed.