title: Signal amplification for electrochemical immunosensing by in situ assembly of host-guest linked gold nanorod superstructure on immunocomplex.
abstract: An amplification strategy for signal tracing was developed by introducing a host-guest binding reaction into the assembly process of gold nanorods (AuNRs) superstructure. The amplification pathway firstly used a thio-β-cyclodextrin (SH-β-CD) functionalized gold nanoparticles to label signal antibody, and then in situ assembled multi-layer SH-β-CD end-functionalized AuNRs to sandwich immunocomplex on immunosensor surface by using 4,4,4,4-(21H, 23H-porphine-5,10,15,20-tetrayl) tetrakis (benzoic acid) as a bridge to achieve simple and convenient host-guest reaction. The built end-to-end AuNRs superstructure showed excellent performance for the signal amplification in connection with the electrochemical biosensing by preoxidation and then voltammetric analysis of gold element. Using α-fetoprotein as an analyte, the immunosensor was constructed by covalently binding capture antibody to chitosan-carbon nanotubes-poly(diallyldimethylammonium chloride) modified electrode. The superstructure rich in AuNRs brought an enhanced detection sensitivity of protein, which could detect α-fetoprotein in a linear range from 0.5 pg mL(-1) to 0.5 ng mL(-1) with a detection limit down to 0.032 pg mL(-1). The immunoassay exhibited good stability and acceptable reproducibility and accuracy. The in situ superstructure assembly could be extended to other labeled recognition systems, providing a promising novel avenue for signal amplification and potential applications in bioanalysis and clinical diagnostics.
authors.affiliation: State Key Laboratory of Analytical Chemistry for Life Science, Department of Chemistry, Nanjing University, Nanjing 210093, PR China.
authors.forename: Dajie
authors.initials: D
authors.lastname: Lin
authors.forename: Jie
authors.initials: J
authors.lastname: Wu
authors.forename: Huangxian
authors.initials: H
authors.lastname: Ju
authors.forename: Feng
authors.initials: F
authors.lastname: Yan
mesh_terms: D000906:Antibodies / Q000737:chemistry / Q000276:immunology; D019817:Benzoic Acid / Q000737:chemistry; D015374:Biosensing Techniques / Q000379:methods*; D003505:Cyclodextrins / Q000737:chemistry; D055664:Electrochemical Techniques; D006046:Gold / Q000737:chemistry; D006801:Humans; D043942:Nanotubes / Q000737:chemistry; D037742:Nanotubes, Carbon / Q000737:chemistry; D000509:alpha-Fetoproteins / Q000032:analysis / Q000276:immunology / Q000302:isolation & purification*
chemical_list: D000906:Antibodies; D003505:Cyclodextrins; D037742:Nanotubes, Carbon; D000509:alpha-Fetoproteins; D006046:Gold; D019817:Benzoic Acid