title: Single Enzyme Direct Biomineralization of CdSe and CdSe-CdS Core-Shell Quantum Dots.
abstract: Biomineralization is the process by which biological systems synthesize inorganic materials. Herein, we demonstrate an engineered cystathionine γ-lyase enzyme, smCSE that is active for the direct aqueous phase biomineralization of CdSe and CdSe-CdS core-shell nanocrystals. The nanocrystals are formed in an otherwise unreactive buffered solution of Cd acetate and selenocystine through enzymatic turnover of the selenocystine to form a reactive precursor, likely H2Se. The particle size of the CdSe core nanocrystals can be tuned by varying the incubation time to generated particle sizes between 2.74 ± 0.63 nm and 4.78 ± 1.16 nm formed after 20 min and 24 h of incubation, respectively. Subsequent purification and introduction of l-cysteine as a sulfur source facilitates the biomineralization of a CdS shell onto the CdSe cores. The quantum yield of the resulting CdSe-CdS core-shell particles is up to 12% in the aqueous phase; comparable to that reported for more traditional chemical synthesis routes for core-shell particles of similar size with similar shell coverage. This single-enzyme route to functional nanocrystals synthesis reveals the powerful potential of biomineralization processes.
authors.affiliation: Department of Chemical and Biomolecular Engineering, Lehigh University , Bethlehem, Pennsylvania 18015, United States.
authors.forename: Zhou
authors.initials: Z
authors.lastname: Yang
authors.affiliation: Department of Materials Science and Engineering, Lehigh University , Bethlehem, Pennsylvania 18015, United States.
authors.forename: Li
authors.identifier: http://orcid.org/0000-0002-6688-1176
authors.initials: L
authors.lastname: Lu
authors.affiliation: Department of Chemical and Biomolecular Engineering, Lehigh University , Bethlehem, Pennsylvania 18015, United States.|Department of Materials Science and Engineering, Lehigh University , Bethlehem, Pennsylvania 18015, United States.
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Kiely
authors.affiliation: Department of Chemical and Biomolecular Engineering, Lehigh University , Bethlehem, Pennsylvania 18015, United States.|Program in Bioengineering, Lehigh University , Bethlehem, Pennsylvania 18015, United States.
authors.forename: Bryan W
authors.initials: BW
authors.lastname: Berger
authors.affiliation: Department of Chemical and Biomolecular Engineering, Lehigh University , Bethlehem, Pennsylvania 18015, United States.
authors.forename: Steven
authors.identifier: http://orcid.org/0000-0003-4664-2028
authors.initials: S
authors.lastname: McIntosh
keywords: cadmium selenide; cadmium sulfide; core-shell; cystathionine γ-lyase; quantum dot; single enzyme biomineralization