Ultrasensitive ELISA using enzyme-loaded nanospherical brushes as labels

Anal Chem. 2014 Oct 7;86(19):9367-71. doi: 10.1021/ac502522b. Epub 2014 Sep 10.


Improving the detection sensitivity of enzyme-linked immunosorbent assay (ELISA) is of utmost importance for meeting the demand of early disease diagnosis. Herein we report an ultrasensitive ELISA system using horseradish peroxidase (HRP)-loaded nanospherical poly(acrylic acid) brushes (SPAABs) as labels. HRP was covalently immobilized in SPAABs with high capacity and activity via an efficient "chemical conjugation after electrostatic entrapment" (CCEE) process, thus endowing SPAABs with high amplification capability as labels. The periphery of SPAAB-HRP was further utilized to bind a layer of antibody with high density for efficient capture of analytes owing to the three-dimensional architecture of SPAABs. Using human chorionic gonadotrophin (hCG) as a model analyte, the SPAAB-amplified system drastically boosted the detection limit of ELISA to 0.012 mIU mL(-1), a 267-fold improvement as compared to conventional ELISA systems.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Acrylic Resins / chemistry
  • Antibodies / chemistry
  • Biosensing Techniques*
  • Chorionic Gonadotropin / blood
  • Electrochemical Techniques
  • Enzyme-Linked Immunosorbent Assay / methods*
  • Enzymes, Immobilized
  • Ferrosoferric Oxide / chemistry
  • Horseradish Peroxidase / chemistry*
  • Humans
  • Limit of Detection
  • Nanostructures / chemistry*
  • Staining and Labeling / methods
  • Static Electricity


  • Acrylic Resins
  • Antibodies
  • Chorionic Gonadotropin
  • Enzymes, Immobilized
  • carbopol 940
  • Horseradish Peroxidase
  • Ferrosoferric Oxide