Biomineralization – the synthesis of inorganic materials using proteins – has recently gained interest as a low cost, green route for the production of metal chalcogenide semiconductor nanocrystals. Typical biomineralization techniques use one of two methods to either catalyze or template the reaction: one type uses enzymes to drive the reaction by producing a reactive chalcogenide species, while the other type uses metal-binding proteins to template the crystallization of a chemical-based synthesis. An idealized biomineralization approach would use proteins with both functionalities, creating a unified system for catalyzing and controlling nanocrystal growth; however, nature has yet to provide such a system. Herein, we demonstrate the biomineralization of metal chalcogenide nanocrystals using a newly synthesized de novo protein, ConK, capable of both catalyzing and templating nanocrystals during growth. Made entirely by design, de novo proteins are highly stable and tolerant to mutations in the amino acid sequence, allowing facile modification and the introduction of new protein functionalities. We created a collection of modified ConK proteins which produce well controlled nanocrystal populations of various size. We characterized the optical properties of the resultant nanocrystal populations using absorbance, fluorescence, and transient absorbance spectroscopy. We verified the crystal structure and nanocrystal size using XRD and TEM measurements. Importantly, semiconductor nanocrystals synthesized using ConK demonstrate improved fluorescence and stability compared to those obtained using naturally derived biomineralization pathways, making de novo biomineralization ideal for commercial implementation.

Biomineralization by design: Application of de novo proteins for nanocrystal synthesis

ACS Fall 2021

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