title: Preparation of peptide-conjugated quantum dots for tumor vasculature-targeted imaging.
abstract: To take full advantage of the unique optical properties of quantum dots (QDs) and expedite future near-infrared fluorescence (NIRF) imaging applications, QDs need to be effectively, specifically and reliably directed to a specific organ or disease site after systemic administration. Recently, we reported the use of peptide-conjugated QDs for non-invasive NIRF imaging of tumor vasculature markers in small animal models. In this protocol, we describe the detailed procedure for the preparation of such peptide-conjugated QDs using commercially available PEG-coated QDs and arginine-glycine-aspartic acid (RGD) peptides. Conjugation of the thiolated RGD peptide to the QDs was achieved through a heterobifunctional linker, 4-maleimidobutyric acid N-succinimidyl ester. Competitive cell binding assay, using (125)I-echistatin as the radioligand, and live cell staining were carried out to confirm the successful attachment of the RGD peptides to the QD surface before in vivo imaging of tumor-bearing mice. In general, QD conjugation and in vitro validation of the peptide-conjugated QDs can be accomplished within 1-2 d; in vivo imaging will take another 1-2 d depending on the experimental design.
authors.affiliation: Molecular Imaging Program at Stanford (MIPS), Department of Radiology and Bio-X Program, Stanford University School of Medicine, Stanford, California 94305, USA.
authors.forename: Weibo
authors.initials: W
authors.lastname: Cai
authors.forename: Xiaoyuan
authors.initials: X
authors.lastname: Chen
mesh_terms: D015415:Biomarkers / Q000032:analysis / Q000737:chemistry; D045744:Cell Line, Tumor; D002851:Chromatography, High Pressure Liquid; D006801:Humans; D007457:Iodine Radioisotopes; D009369:Neoplasms / Q000098:blood supply* / Q000473:pathology; D009842:Oligopeptides / Q000032:analysis* / Q000737:chemistry; D045663:Quantum Dots; D013050:Spectrometry, Fluorescence / Q000379:methods*; D019265:Spectroscopy, Near-Infrared / Q000379:methods*
chemical_list: D015415:Biomarkers; D007457:Iodine Radioisotopes; D009842:Oligopeptides; C047981:arginyl-glycyl-aspartic acid