title: Magnetic electrochemiluminescent Fe3O4/CdSe-CdS nanoparticle/polyelectrolyte nanocomposite for highly efficient immunosensing of a cancer biomarker.
abstract: Magnetic electrochemiluminescent Fe(3)O(4)/CdSe-CdS nanoparticle/polyelectrolyte nanostructures have been synthesized and used to fabricate an electrochemiluminescence (ECL) immunosensor for the detection of carcinoembryonic antigen (CEA). CEA is a protein used as a biomarker for several cancers; particularly, to monitor response to treatment in colon and rectal cancer patients. The nanocomposites can be easily separated and firmly attached to an electrode owing to their excellent magnetic properties. This represents a promising advantage for bioassay applications. More importantly, the nanostructures exhibit intense and stable ECL emissions in neutral solution, which makes them ideal for ECL immunosensing. The 3-aminopropyltriethoxysilane (APS) polyelectrolyte shell on the nanostructure surface not only enhances the intensity and stability of the ECL signal, but also acts as a crosslinker for immunosensor fabrication. A CEA antibody immobilized onto a nanocomposite/APS/electrode with gold nanoparticles comprises the ECL immunosensor. The principle of ECL detection for CEA is based on a change in steric hindrance after immunoreaction, which leads to a decrease in ECL intensity. A wide detection range (0.064 pg  ml(-1)-10 ng  ml(-1)) and low detection limit (0.032 pg  ml(-1)) are achieved. The immunosensor is highly sensitive and selective, and exhibits excellent stability and good reproducibility. It thus has great potential for clinical protein detection. In particular, this approach uses a novel class of bifunctional nanocomposites that display both intense ECL and excellent magnetism, which renders them suitable for a large range of bioassay applications.
authors.affiliation: State Key Laboratory Base of Eco-chemical Engineering, College of Chemistry and Molecular Engineering, Qingdao University of Science and Technology, Qingdao, 266042, PR China.
authors.forename: Guifen
authors.initials: G
authors.lastname: Jie
authors.forename: Lei
authors.initials: L
authors.lastname: Wang
authors.forename: Shusheng
authors.initials: S
authors.lastname: Zhang
mesh_terms: D014408:Biomarkers, Tumor / Q000032:analysis; D015374:Biosensing Techniques; D002272:Carcinoembryonic Antigen / Q000032:analysis*; D003110:Colonic Neoplasms / Q000175:diagnosis; D052203:Ferrosoferric Oxide / Q000737:chemistry*; D006801:Humans; D008163:Luminescent Measurements; D053761:Nanocomposites / Q000737:chemistry*; D012004:Rectal Neoplasms / Q000175:diagnosis
chemical_list: D014408:Biomarkers, Tumor; D002272:Carcinoembryonic Antigen; D052203:Ferrosoferric Oxide