Comparative sensitivity of immunoassays for haptens using monomeric and dimeric antibody fragments

S D Grant, A J Porter, W J Harris

Research output: Contribution to journalArticle

24 Citations (Scopus)


A single-chain anti-atrazine antibody fragment, scAb (single-chain Fv with a CK domain), was expressed in Escherichia coli, and monomeric and dimeric species were preferentially purified from periplasmic extracts by chromatography upon nickel chelate immunosorbent columns or by immunoaffinity purification using a constant domain (CK) tag. Recombinant monomeric and dimeric antibody fragments, Fab, and intact monoclonal antibodies were compared in assays by competition between free atrazine in solution and (a) immobilized atrazine-bovine serum albumin conjugate (indirect assay) or (b) atrazine-alkaline phosphatase (direct assay). Recombinant antibody fragments provided a lower detection Limit than either Fab or intact monoclonal antibody in both assay formats. Monomeric fragments displayed a sensitivity of detection down to 0.1 ppb, compared to 1.0 ppb for dimeric fragments and the parental monoclonal.

Original languageEnglish
Pages (from-to)340-345
Number of pages6
JournalJournal of Agricultural and Food Chemistry
Issue number1
Early online date20 Nov 1998
Publication statusPublished - 1999


  • antibody fragments
  • immunoassays
  • single-chain antibodies
  • anti-haptens
  • triazines
  • enzyme-immunoassay
  • monoclonal-antibodies
  • triazine herbicides
  • atrazine
  • expression
  • cloning
  • FV
  • construction
  • technology


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