title: Oriented conjugates of single-domain antibodies and quantum dots: toward a new generation of ultrasmall diagnostic nanoprobes.
abstract: Common strategy for diagnostics with quantum dots (QDs) utilizes the specificity of monoclonal antibodies (mAbs) for targeting. However QD-mAbs conjugates are not always well-suited for this purpose because of their large size. Here, we engineered ultrasmall nanoprobes through oriented conjugation of QDs with 13-kDa single-domain antibodies (sdAbs) derived from llama IgG. Monomeric sdAbs are 12 times smaller than mAbs and demonstrate excellent capacity for refolding. sdAbs were tagged with QDs through an additional cysteine residue integrated within the C terminal of the sdAb. This approach allowed us to develop sdAbs-QD nanoprobes comprising four copies of sdAbs coupled with a QD in a highly oriented manner. sdAbs-QD conjugates specific to carcinoembryonic antigen (CEA) demonstrated excellent specificity of flow cytometry quantitative discrimination of CEA-positive and CEA-negative tumor cells. Moreover, the immunohistochemical labeling of biopsy samples was found to be comparable or even superior to the quality obtained with gold standard protocols of anatomopathology practice. sdAbs-QD-oriented conjugates as developed represent a new generation of ultrasmall diagnostic probes for applications in high-throughput diagnostic platforms.
  
  
  BACKGROUND
  The authors report the development of sdAbs-QD-oriented conjugates, comprised of single domain antibodies that are 12 times smaller than regular mAb-s and quantum dots. These ultrasmall diagnostic probes represent a new generation of functionalized ODs for applications in high-throughput diagnostic platforms.
authors.affiliation: EA3798 Détection et Approches Thérapeutiques Nanotechnologiques dans les Mécanismes Biologiques de Défense, Université de Reims Champagne-Ardenne, Reims, France.
authors.forename: Alyona
authors.initials: A
authors.lastname: Sukhanova
authors.forename: Klervi
authors.initials: K
authors.lastname: Even-Desrumeaux
authors.forename: Aymric
authors.initials: A
authors.lastname: Kisserli
authors.forename: Thierry
authors.initials: T
authors.lastname: Tabary
authors.forename: Brigitte
authors.initials: B
authors.lastname: Reveil
authors.forename: Jean-Marc
authors.initials: JM
authors.lastname: Millot
authors.forename: Patrick
authors.initials: P
authors.lastname: Chames
authors.forename: Daniel
authors.initials: D
authors.lastname: Baty
authors.forename: Mikhail
authors.initials: M
authors.lastname: Artemyev
authors.forename: Vladimir
authors.initials: V
authors.lastname: Oleinikov
authors.forename: Michel
authors.initials: M
authors.lastname: Pluot
authors.forename: Jacques H M
authors.initials: JH
authors.lastname: Cohen
authors.forename: Igor
authors.initials: I
authors.lastname: Nabiev
mesh_terms: D000818:Animals; D002161:Camelids, New World; D002272:Carcinoembryonic Antigen / Q000737:chemistry; D045744:Cell Line, Tumor; D006801:Humans; D007074:Immunoglobulin G / Q000737:chemistry*; D015335:Molecular Probes / Q000737:chemistry*; D009369:Neoplasms / Q000175:diagnosis; D045663:Quantum Dots; D057127:Single-Chain Antibodies / Q000737:chemistry*
chemical_list: D002272:Carcinoembryonic Antigen; D007074:Immunoglobulin G; D015335:Molecular Probes; D057127:Single-Chain Antibodies