title: Photophysics of (CdSe)ZnS colloidal quantum dots in an aqueous environment stabilized with amino acids and genetically-modified proteins.
abstract: Using a combination of two amino acids, histidine and N-acetyl-cysteine, to replace the original organic capping groups of (CdSe)ZnS quantum dots, water-soluble and highly luminescent (CdSe)ZnS quantum dots have been successfully prepared at pH 8. Characterization by steady-state and time-resolved photoluminescence spectroscopy, and transient absorption spectroscopy, demonstrate that the electronic properties of these quantum dots exceed those of the original as-synthesized samples dissolved in a more-conventional organic solvent. Furthermore, these amino acid-stabilized quantum dots have been assembled onto a cellulose substrate via cellulose binding proteins that specifically bind to cellulose and was genetically engineered to harbor dual hexahistidine tags at the N- and C-termini to confer binding with the zinc(II) on the quantum dot surface. The spectroscopic measurements show that the protein-bound quantum dots continue to retain their desirable electronic properties when bound on the substrate. Meanwhile, the specific and very selective binding properties of the proteins have remained effective.
authors.affiliation: National Renewable Energy Laboratory, 1617 Cole Blvd, Golden, CO 80401-3393, USA.
authors.forename: Xin
authors.initials: X
authors.lastname: Ai
authors.forename: Qi
authors.initials: Q
authors.lastname: Xu
authors.forename: Marcus
authors.initials: M
authors.lastname: Jones
authors.forename: Qing
authors.initials: Q
authors.lastname: Song
authors.forename: Shi-you
authors.initials: SY
authors.lastname: Ding
authors.forename: Randy J
authors.initials: RJ
authors.lastname: Ellingson
authors.forename: Mike
authors.initials: M
authors.lastname: Himmel
authors.forename: Garry
authors.initials: G
authors.lastname: Rumbles
mesh_terms: D000596:Amino Acids / Q000235:genetics / Q000378:metabolism*; D019187:Cadmium Compounds / Q000737:chemistry*; D002480:Cellulase / Q000235:genetics / Q000378:metabolism*; D003102:Colloids; D046529:Microscopy, Electron, Transmission; D015394:Molecular Structure; D010777:Photochemistry; D045663:Quantum Dots; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D018036:Selenium Compounds / Q000737:chemistry*; D017967:Zinc Compounds / Q000737:chemistry*
chemical_list: D000596:Amino Acids; D019187:Cadmium Compounds; D003102:Colloids; D011994:Recombinant Proteins; D018036:Selenium Compounds; D017967:Zinc Compounds; C058667:cadmium selenide; D002480:Cellulase