title: A reactive peptidic linker for self-assembling hybrid quantum dot-DNA bioconjugates.
abstract: Self-assembly of proteins, peptides, DNA, and other biomolecules to semiconductor quantum dots (QD) is an attractive bioconjugation route that can circumvent many of the problems associated with covalent chemistry and subsequent purification. Polyhistidine sequences have been shown to facilitate self-assembly of proteins and peptides to ZnS-overcoated CdSe QDs via complexation to unoccupied coordination metal sites on the nanocrystal surface. We describe the synthesis and characterization of a thiol-reactive hexahistidine peptidic linker that can be chemically attached to thiolated-DNA oligomers and mediate their self-assembly to CdSe-ZnS core-shell QDs. The self-assembly of hexahistidine-appended DNA to QDs is probed with gel electrophoresis and fluorescence resonance energy transfer techniques, and the results confirm high-affinity conjugate formation with control over the average molar ratio of DNA assembled per QD. To demonstrate the potential of this reactive peptide linker strategy, a prototype QD-DNA-dye molecular beacon is self-assembled and tested against both specific and nonspecific target DNAs. This conjugation route is potentially versatile, as altering the reactivity of the peptide linker may allow targeting of different functional groups such as amines and facilitate self-assembly of other nanoparticle-biomolecule structures.
authors.affiliation: U.S. Naval Research Laboratory, Center for Bio/Molecular Science and Engineering Code 6900, Division of Optical Sciences Code 5611, Washington, DC 20375, USA. berti.lorenzo@unimo.it
authors.forename: Igor L
authors.initials: IL
authors.lastname: Medintz
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Berti
authors.forename: Thomas
authors.initials: T
authors.lastname: Pons
authors.forename: Amy F
authors.initials: AF
authors.lastname: Grimes
authors.forename: Douglas S
authors.initials: DS
authors.lastname: English
authors.forename: Andrea
authors.initials: A
authors.lastname: Alessandrini
authors.forename: Paolo
authors.initials: P
authors.lastname: Facci
authors.forename: Hedi
authors.initials: H
authors.lastname: Mattoussi
mesh_terms: D003432:Cross-Linking Reagents / Q000737:chemistry; D003460:Crystallization / Q000379:methods; D004247:DNA / Q000737:chemistry* / Q000648:ultrastructure*; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000648:ultrastructure; D046911:Macromolecular Substances / Q000737:chemistry; D008422:Materials Testing; D008968:Molecular Conformation; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure; D036103:Nanotechnology / Q000379:methods*; D010316:Particle Size; D010455:Peptides / Q000737:chemistry*; D045663:Quantum Dots; D013194:Staining and Labeling / Q000379:methods*; D013499:Surface Properties
chemical_list: D003432:Cross-Linking Reagents; D004268:DNA-Binding Proteins; D046911:Macromolecular Substances; D010455:Peptides; D004247:DNA