(328c) De Novo Protein Systems for the Controllable Biomineralization of Semiconductor Quantum Dots

Biomineralization is a scalable, green, and sustainable method for producing a wide range of functional nanomaterials such as semiconductor quantum dots, metal nanoparticles, and reduced graphene oxide photocatalytic supports. In contrast to traditional chemical synthesis, biomineralization occurs under ambient temperatures and pressures using proteins or other biomolecules to drive mineralization. While biomineralized functional materials are made sustainably, they often suffer in quality because their synthesis relies on biochemical pathways that were initially evolved for biologically relevant materials. For example, proteins used to biomineralize semiconductor quantum dots are typically taken from natural organisms and applied without optimization, resulting in nanocrystals with low fluorescence quantum yields. To better control the properties of biomineralized nanomaterials, we have developed two de novo protein systems that can be optimized to produce inorganic materials for non-biological applications. De novo proteins have no evolutionary biases because they are made by design using a binary polar-nonpolar amino acid motif. The resultant proteins are highly stable and tolerant to modification, enabling tunability of protein function. Here, we demonstrate two de novo proteins developed for the controllable biomineralization of metal chalcogenide quantum dots. The first protein catalyzes the synthesis, while the second serves to template and stabilize nanocrystal growth. For each de novo protein system, we demonstrate optimization of subsequent nanocrystal properties by tuning amino acids within the protein, establishing a pathway for improving the performance of other biomineralized functional materials in the future.