Antibody Mimetics for the Detection of Small Organic Compounds Using a Quartz Crystal Microbalance

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, nonimmunogenic 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 bioreceptors for the detection of small organic target compounds, here methylene blue. Target immobilization for Affimer characterization was achieved using long-chained alkanethiol linkers coupled with oligoethylene glycol (LCAT–OEG). Using quartz crystal microbalance with dissipation monitoring (...