Nano-magnetic immunosensor based on staphylococcus protein a and the amplification effect of HRP-conjugated phage antibody

Sensors (Basel). 2015 Feb 9;15(2):3896-910. doi: 10.3390/s150203896.

Abstract

In this research, super-paramagnetic Fe3O4 nanoparticles (magnetic particles) were coated with Staphylococcus protein A (SPA) and coupled with polyclonal antibody (pcAb) to construct magnetic capturing probes, and HRP-conjugated phage antibody was then used as specific detecting probe to design a labeled immunosensor for trace detection of Staphylococcus aureus enterotoxin B (SEB). The linear detection range of the sensor was 0.008~125 µg/L, the regression equation was Y = 0.487X + 1.2 (R = 0.996, N = 15, p < 0.0001), the limit of detection (LOD) was 0.008 µg/L, and the limit of quantification (LOQ) was 0.008 µg/L. HRP-conjugated phage antibody, SPA and magnetic particles can enhance the sensitivity 4-fold, 3-fold and 2.6-fold higher, respectively. Compared with conventional double-antibody sandwich ELISA, the detection sensitivity of the sensor was 31-fold higher resulting from the integrated amplifying effect. The immunosensor integrates the unique advantages of SPA-oriented antibody as magnetic capturing probe, HRP-conjugated phage antibody as detecting probe, magnetic separation immunoassay technique, and several other advanced techniques, so it achieves high sensitivity, specificity and interference-resistance. It is proven to be well suited for analysis of trace SEB in various environmental samples with high recovery rate and reproducibility.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antibodies / chemistry
  • Antibodies / immunology
  • Bacteriophages / chemistry
  • Biosensing Techniques*
  • Enterotoxins / immunology
  • Enterotoxins / isolation & purification*
  • Enzyme-Linked Immunosorbent Assay
  • Gold / chemistry
  • Humans
  • Limit of Detection
  • Magnetite Nanoparticles / chemistry*
  • Staphylococcal Protein A / chemistry
  • Staphylococcus aureus / immunology
  • Staphylococcus aureus / isolation & purification*

Substances

  • Antibodies
  • Enterotoxins
  • Magnetite Nanoparticles
  • Staphylococcal Protein A
  • enterotoxin B, staphylococcal
  • Gold