title: Multiphoton imaging of tumor biomarkers with conjugates of single-domain antibodies and quantum dots.
abstract: An ideal multiphoton fluorescent nanoprobe should combine a nanocrystal with the largest possible two-photon absorption cross section (TPACS) and the smallest highly specific recognition molecules bound in an oriented manner. CdSe/ZnS quantum dots (QDs) conjugated to 13-kDa single-domain antibodies (sdAbs) derived from camelid IgG or streptavidin have been used as efficient two-photon excitation (TPE) probes for carcinoembryonic antigen (CEA) imaging on normal human appendix and colon carcinoma tissue. The TPACS for some conjugates was higher than 49,000 GM (Goeppert-Mayer units), considerably exceeding that of organic dyes being close to the theoretical value of 50,000 GM calculated for CdSe QDs. The ratio of sdAb-QD emission to the autofluorescence for 800 nm TPE was 40 times higher than that for 457.9 nm one-photon excitation. TPE ensures a clear discrimination of CEA-overexpressing tumor areas from normal tissue. Oriented sdAb-QD conjugates are bright specific labels for detecting low concentrations of antigens using multiphoton microscopy.
  
  
  BACKGROUND
  This study demonstrates carcinoembryonic antigen imaging on normal human appendix and colon carcinoma tissue utilizing CdSe/ZnS quantum dots conjugated to streptavidin or to 13-kDa single-domain antibodies as efficient two-photon excitation probes.
authors.affiliation: Laboratoire de Recherche en Nanosciences (LRN)-EA4682, Université de Reims Champagne-Ardenne, Reims, France.
authors.forename: Hilal
authors.initials: H
authors.lastname: Hafian
authors.affiliation: Laboratoire de Recherche en Nanosciences (LRN)-EA4682, Université de Reims Champagne-Ardenne, Reims, France; Laboratory of Nano-Bioengineering, National Research Nuclear University "MEPhI" (Moscow Engineering Physics Institute), Moscow, Russian Federation.
authors.forename: Alyona
authors.initials: A
authors.lastname: Sukhanova
authors.affiliation: Inserm U1068, CRCM, Marseille, France; Institut Paoli-Calmettes, Marseille, France; Aix-Marseille Univ UM105, Marseille, France; CNRS UMR7258, CRCM, Marseille, France.
authors.forename: Marc
authors.initials: M
authors.lastname: Turini
authors.affiliation: Inserm U1068, CRCM, Marseille, France; Institut Paoli-Calmettes, Marseille, France; Aix-Marseille Univ UM105, Marseille, France; CNRS UMR7258, CRCM, Marseille, France.
authors.forename: Patrick
authors.initials: P
authors.lastname: Chames
authors.affiliation: Inserm U1068, CRCM, Marseille, France; Institut Paoli-Calmettes, Marseille, France; Aix-Marseille Univ UM105, Marseille, France; CNRS UMR7258, CRCM, Marseille, France.
authors.forename: Daniel
authors.initials: D
authors.lastname: Baty
authors.affiliation: Laboratoire de Recherche en Nanosciences (LRN)-EA4682, Université de Reims Champagne-Ardenne, Reims, France.
authors.forename: Michel
authors.initials: M
authors.lastname: Pluot
authors.affiliation: Laboratoire de Recherche en Nanosciences (LRN)-EA4682, Université de Reims Champagne-Ardenne, Reims, France.
authors.forename: Jacques H M
authors.initials: JH
authors.lastname: Cohen
authors.affiliation: Laboratoire de Recherche en Nanosciences (LRN)-EA4682, Université de Reims Champagne-Ardenne, Reims, France; Laboratory of Nano-Bioengineering, National Research Nuclear University "MEPhI" (Moscow Engineering Physics Institute), Moscow, Russian Federation. Electronic address: igor.nabiev@gmail.com.
authors.forename: Igor
authors.initials: I
authors.lastname: Nabiev
authors.affiliation: Laboratoire de Recherche en Nanosciences (LRN)-EA4682, Université de Reims Champagne-Ardenne, Reims, France. Electronic address: jm.millot@univ-reims.fr.
authors.forename: Jean-Marc
authors.initials: JM
authors.lastname: Millot
mesh_terms: D000818:Animals; D014408:Biomarkers, Tumor; D003952:Diagnostic Imaging / Q000379:methods*; D066298:In Vitro Techniques; D045663:Quantum Dots; D061905:Single-Domain Antibodies / Q000737:chemistry*
chemical_list: D014408:Biomarkers, Tumor; D061905:Single-Domain Antibodies
keywords: Diagnostic nanoprobes; Immunohistochemistry; Quantum dots; Single-domain antibodies; Two-photon imaging