title: Rotational and translational diffusion of peptide-coated CdSe/CdS/ZnS nanorods studied by fluorescence correlation spectroscopy.
abstract: CdSe/CdS/ZnS nanorods (NRs) of three aspect ratios were coated with phytochelatin-related peptides and studied using fluorescence correlation spectroscopy (FCS). Theoretical predictions of the NRs' rotational diffusion contribution to the correlation curves were experimentally confirmed. We monitored rotational and translational diffusion of NRs and extracted hydrodynamic radii from the extracted diffusion constants. Translational and rotational diffusion constants (D(trans) and D(rot)) for NRs were in good agreement with Tirado and Garcia de la Torre's as well as with Broersma's theories when accounting for the ligand dimensions. NRs fall in the size range where rotational diffusion can be monitored with higher sensitivity than translational diffusion due to a steeper length dependence, D(rot) approximately L(-)(3) versus D(trans) approximately L(-)(1). By titrating peptide-coated NRs with bovine serum albumin, we monitored (nonspecific) binding through rotational diffusion and showed that D(rot) is an advantageous observable for monitoring binding. Monitoring rotational diffusion of bioconjugated NRs using FCS might prove to be useful for observing binding and conformational dynamics in biological systems.
authors.affiliation: Department of Chemistry and Biochemistry, University of California at Los Angeles, Los Angeles, California 90095, USA.
authors.forename: James M
authors.initials: JM
authors.lastname: Tsay
authors.forename: Sören
authors.initials: S
authors.lastname: Doose
authors.forename: Shimon
authors.initials: S
authors.lastname: Weiss
mesh_terms: D000595:Amino Acid Sequence; D019187:Cadmium Compounds / Q000737:chemistry*; D004058:Diffusion; D008956:Models, Chemical; D008969:Molecular Sequence Data; D049329:Nanostructures / Q000737:chemistry*; D010455:Peptides / Q000737:chemistry*; D018036:Selenium Compounds / Q000737:chemistry*; D012710:Serum Albumin, Bovine / Q000737:chemistry; D013050:Spectrometry, Fluorescence / Q000379:methods; D013440:Sulfides / Q000737:chemistry*; D017967:Zinc Compounds / Q000737:chemistry*
chemical_list: D019187:Cadmium Compounds; D010455:Peptides; D018036:Selenium Compounds; D013440:Sulfides; D017967:Zinc Compounds; C034939:cadmium sulfide; D012710:Serum Albumin, Bovine; C058667:cadmium selenide; C031238:zinc sulfide