title: Versatile immunosensor using a quantum dot coated silica nanosphere as a label for signal amplification.
abstract: A versatile immunosensor using a CdTe quantum dots (QDs) coated silica nanosphere (Si/QD) as a label was proposed for ultrasensitive detection of a biomarker. In this approach, silica nanospheres with good monodispersity and uniform structure were employed as the carrier for immobilization of QDs and antibodies. Rabit IgG served as a model protein to demonstrate the performance of the immunosensor. Goat antirabbit IgG antibody was covalently bound to CdTe QDs on the surface of silica nanospheres. CdTe QDs coated with a silica nanosphere label (Si/QD/Ab2) were attached onto the gold electrode surface through a subsequent "sandwich" immunoreaction. This reaction was confirmed by scanning electron microscopic (SEM) and fluorescence microscopic images. Due to signal amplification from the high loading of CdTe QDs, 6.6- and 5.9-fold enhancements in electrochemiluminescent (ECL) and square-wave voltammetric (SWV) signals for IgG detection were achieved compared to the unamplified method. The detection limits for IgG were 1.3 and 0.6 pg mL(-1) for ECL and SWV measurements, respectively. The resulting versatile immunosensor possesses high sensitivity, satisfactory reproducibility and regeneration, and good precision. This simple and specific strategy has vast potential to be used in other biological assays.
authors.affiliation: State Key Laboratory of Bioelectronics, School of Chemistry and Chemical Engineering, Southeast University, Nanjing, 211189, People's Republic of China.
authors.forename: Jing
authors.initials: J
authors.lastname: Qian
authors.forename: Chunyan
authors.initials: C
authors.lastname: Zhang
authors.forename: Xiaodong
authors.initials: X
authors.lastname: Cao
authors.forename: Songqin
authors.initials: S
authors.lastname: Liu
mesh_terms: D000818:Animals; D000906:Antibodies / Q000737:chemistry / Q000276:immunology; D015374:Biosensing Techniques / Q000379:methods; D019187:Cadmium Compounds / Q000737:chemistry; D055664:Electrochemical Techniques / Q000379:methods*; D004566:Electrodes; D006041:Goats; D006046:Gold / Q000737:chemistry; D007118:Immunoassay / Q000379:methods; D007074:Immunoglobulin G / Q000032:analysis / Q000276:immunology; D045663:Quantum Dots; D011817:Rabbits; D012822:Silicon Dioxide / Q000737:chemistry*; D013691:Tellurium / Q000737:chemistry
chemical_list: D000906:Antibodies; D019187:Cadmium Compounds; D007074:Immunoglobulin G; D006046:Gold; D012822:Silicon Dioxide; D013691:Tellurium; C028337:cadmium telluride