title: A new signal amplification strategy of photoelectrochemical immunoassay for highly sensitive interleukin-6 detection based on TiO2/CdS/CdSe dual co-sensitized structure.
abstract: Dual co-sensitized structure of TiO2/CdS/CdSe was designed to develop a novel photoelectrochemical immunoassay for highly sensitive detection of human interleukin-6 (IL-6). To construct a sensing electrode, TiO2/CdS hybrid was prepared by successive adsorption and reaction of Cd(2+) and S(2-) ions on the surface of TiO2 and then was employed as matrix for immobilization of anti-IL-6 antibody, whereas CdSe QDs linked to IL-6 were used for signal amplification via the specific antibody-antigen immunoreaction between anti-IL-6 and IL-6-CdSe bioconjugate. Greatly enhanced sensitivity for IL-6 detection was derived from the new co-sensitization signal amplification strategy. First, the TiO2/CdS/CdSe co-sensitized structure extended the absorption range to long wavelength of white light, which adequately utilized the light energy. Second, the TiO2/CdS/CdSe co-sensitized structure possessed stepwise band-edge levels favoring ultrafast transfer of photogenerated electrons and significantly prompted the photoelectrochemical performance. Besides, the introduction of CdSe effectively prevented the recombination of photogenerated electrons in the conduction band of CdS, further causing an enhanced photocurrent. Accordingly, upon the co-sensitization strategy, a novel immunoassay based on the competitive binding of anti-IL-6 antibody with IL-6 antigen and IL-6-CdSe bioconjugate was developed, and it exhibited a wide linear range from 1.0 pg/mL to 100 ng/mL with a low detection limit of 0.38 pg/mL for IL-6 detection. The proposed co-sensitization strategy presented high sensitivity, reproducibility, specificity and stability, and also opened up a new promising platform for detection of other biomarkers.
authors.affiliation: State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry & Chemical Engineering, Nanjing University, Nanjing 210093, PR China.
authors.forename: Gao-Chao
authors.initials: GC
authors.lastname: Fan
authors.affiliation: State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry & Chemical Engineering, Nanjing University, Nanjing 210093, PR China.
authors.forename: Xiao-Lin
authors.initials: XL
authors.lastname: Ren
authors.affiliation: State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry & Chemical Engineering, Nanjing University, Nanjing 210093, PR China.
authors.forename: Cheng
authors.initials: C
authors.lastname: Zhu
authors.affiliation: State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry & Chemical Engineering, Nanjing University, Nanjing 210093, PR China; School of Chemistry and Life Science, Nanjing University Jinling College, Nanjing 210089, PR China. Electronic address: jrzhang@nju.edu.cn.
authors.forename: Jian-Rong
authors.initials: JR
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry & Chemical Engineering, Nanjing University, Nanjing 210093, PR China. Electronic address: jjzhu@nju.edu.cn.
authors.forename: Jun-Jie
authors.initials: JJ
authors.lastname: Zhu
mesh_terms: D055910:Antibodies, Immobilized / Q000737:chemistry; D019187:Cadmium Compounds / Q000737:chemistry*; D055664:Electrochemical Techniques / Q000295:instrumentation*; D004566:Electrodes; D004867:Equipment Design; D006801:Humans; D007118:Immunoassay / Q000295:instrumentation*; D015850:Interleukin-6 / Q000032:analysis*; D057230:Limit of Detection; D045663:Quantum Dots / Q000737:chemistry* / Q000648:ultrastructure; D018036:Selenium Compounds / Q000737:chemistry*; D013440:Sulfides / Q000737:chemistry*; D014025:Titanium / Q000737:chemistry*
chemical_list: D055910:Antibodies, Immobilized; D019187:Cadmium Compounds; D015850:Interleukin-6; D018036:Selenium Compounds; D013440:Sulfides; C034939:cadmium sulfide; C009495:titanium dioxide; C058667:cadmium selenide; D014025:Titanium
keywords: Co-sensitization; Competitive immunoassay; Human interleukin-6; Photoelectrochemistry