Antibody mimetics for the detection of small organic compounds using a quartz crystal microbalance

Eleni Koutsoumpeli, Christian Tiede, James Murray, Anna Tang, Robin Bon, Darren Tomlinson, Steven David Johnson

Research output: Contribution to journalArticlepeer-review


Conventional immunoassays rely on antibodies that provide high affinity, specificity and selectivity against a target analyte. However, the use of antibodies for the detection of small-sized, non-immunogenic targets, such as pharmaceuticals and environmental contaminants presents a number of challenges. Recent advances in protein engineering have led to the emergence of antibody mimetics that offer the high affinity and specificity associated with antibodies but with reduced batch-to- batch variability, high stability and in vitro selection to ensure rapid discovery of binders against a wide range of targets. In this work we explore the potential of Affimers, a recent example of antibody mimetics, as suitable bio-receptors for the detection of small organic target compounds, here methylene blue. Target immobilisation for Affimer characterisation was achieved using long-chained alkanethiol linkers coupled with oligoethyleneglycol (LCAT-OEG). Using quartz crystal microbalance with dissipation monitoring (QCM-D), we determine the affinity constant, KD , of the methylene blue Affimer to be comparable to that of antibodies. Further, we demonstrate the high selectivity of Affimers for its target in complex matrices, here a limnetic sample. Finally, we demonstrate an Affimer-based competition assay, illustrating the potential of Affimers as bioreceptors in immunoassays for the detection of small-sized, non-immunogenic compounds.
Original languageEnglish
Pages (from-to)3051-3058
Number of pages8
JournalAnalytical Chemistry
Issue number5
Early online date1 Feb 2017
Publication statusPublished - 7 Mar 2017

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