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Direct electrochemical immunoassay based on a silica nanoparticles/sol–gel composite architecture for encapsulation of immunoconjugate


A highly hydrophobic and non-toxic colloidal silica nanoparticle/polyvinyl butyral sol–gel composite membrane was prepared on a platinum wire electrode. With diphtheria-toxoid (D-Ag) as a model antigen and encapsulation of diphtheria antibody (D-Ab) in the composite architecture, this membrane could be used for reagentless electrochemical immunoassay. It displayed a porous and homogeneous composite architecture without the aggregation of the immobilized protein molecules. The formation of immunoconjugate by a simple one-step immunoreaction between D-Ag in sample solution and the immobilized D-Ab introduced the change in the potential. Under optimal conditions, the D-Ag analyte could be determined in the linear ranges from 10 to 800 ng ml−1 with a relatively low detection limit of 2.3 ng ml−1 at 3δ. The D-Ag immunosensor exhibited good precision, high sensitivity, acceptable stability, accuracy, and reproducibility. This composite membrane could be used efficiently for the entrapment of different biomarkers and clinical applications.

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This work was supported by the NNSF of China (29705001), the Chinese Education Ministry Foundation for Excellent Young Teachers (No. 2002-40) and the NSF of Chongqing City (No. 20027477), China.

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Correspondence to Ruo Yuan.

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Wang, F., Yuan, R. & Chai, Y. Direct electrochemical immunoassay based on a silica nanoparticles/sol–gel composite architecture for encapsulation of immunoconjugate. Appl Microbiol Biotechnol 72, 671–675 (2006). https://doi.org/10.1007/s00253-006-0353-2

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  • Silica Nanoparticles
  • Composite Membrane
  • Diphtheria
  • Potentiometric Response
  • Polyvinyl Butyral