title: The sandwich-type electrochemiluminescence immunosensor for α-fetoprotein based on enrichment by Fe3O4-Au magnetic nano probes and signal amplification by CdS-Au composite nanoparticles labeled anti-AFP.
abstract: A novel and sensitive sandwich-type electrochemiluminescence (ECL) immunosensor was fabricated on a glassy carbon electrode (GCE) for ultra trace levels of α-fetoprotein (AFP) based on sandwich immunoreaction strategy by enrichment using magnetic capture probes and quantum dots coated with Au shell (CdS-Au) as the signal tag. The capture probe was prepared by immobilizing the primary antibody of AFP (Ab1) on the core/shell Fe(3)O(4)-Au nanoparticles, which was first employed to capture AFP antigens to form Fe(3)O(4)-Au/Ab1/AFP complex from the serum after incubation. The product can be separated from the background solution through the magnetic separation. Then the CdS-Au labeled secondary antibody (Ab2) as signal tag (CdS-Au/Ab2) was conjugated successfully with Fe(3)O(4)-Au/Ab1/AFP complex to form a sandwich-type immunocomplex (Fe(3)O(4)-Au/Ab1/AFP/Ab2/CdS-Au), which can be further separated by an external magnetic field and produce ECL signals at a fixed voltage. The signal was proportional to a certain concentration range of AFP for quantification. Thus, an easy-to-use immunosensor with magnetic probes and a quantum dots signal tag was obtained. The immunosensor performed at a level of high sensitivity and a broad concentration range for AFP between 0.0005 and 5.0 ng mL(-1) with a detection limit of 0.2 pg mL(-1). The use of magnetic probes was combined with pre-concentration and separation for trace levels of tumor markers in the serum. Due to the amplification of the signal tag, the immunosensor is highly sensitive, which can offer great promise for rapid, simple, selective and cost-effective detection of effective biomonitoring for clinical application.
authors.affiliation: The State Key Laboratory Base of Novel Functional Materials and Preparation Science, Faculty of Material Science and Chemical Engineering of Ningbo University, Ningbo 315211, China.
authors.forename: Hankun
authors.initials: H
authors.lastname: Zhou
authors.forename: Ning
authors.initials: N
authors.lastname: Gan
authors.forename: Tianhua
authors.initials: T
authors.lastname: Li
authors.forename: Yuting
authors.initials: Y
authors.lastname: Cao
authors.forename: Saolin
authors.initials: S
authors.lastname: Zeng
authors.forename: Lei
authors.initials: L
authors.lastname: Zheng
authors.forename: Zhiyong
authors.initials: Z
authors.lastname: Guo
mesh_terms: D000818:Animals; D000906:Antibodies / Q000737:chemistry / Q000276:immunology; D014408:Biomarkers, Tumor / Q000032:analysis* / Q000276:immunology; D015374:Biosensing Techniques; D019187:Cadmium Compounds / Q000737:chemistry; D002417:Cattle; D055664:Electrochemical Techniques; D004566:Electrodes; D052203:Ferrosoferric Oxide / Q000737:chemistry; D006046:Gold / Q000737:chemistry; D006801:Humans; D057230:Limit of Detection; D008163:Luminescent Measurements / Q000379:methods; D058185:Magnetite Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure; D046529:Microscopy, Electron, Transmission; D045663:Quantum Dots; D012680:Sensitivity and Specificity; D013440:Sulfides / Q000737:chemistry; D000509:alpha-Fetoproteins / Q000032:analysis* / Q000737:chemistry / Q000276:immunology
chemical_list: D000906:Antibodies; D014408:Biomarkers, Tumor; D019187:Cadmium Compounds; D058185:Magnetite Nanoparticles; D013440:Sulfides; D000509:alpha-Fetoproteins; C034939:cadmium sulfide; D006046:Gold; D052203:Ferrosoferric Oxide