Quantifying monoclonal antibodies in serum with Alto™ Digital SPR


As the first digital microfluidic (DMF) powered surface plasmon resonance (SPR) instrument in the market, Alto provides users with a quantitation assay to quantify proteins of interest in various mediums, including crude samples. Commonly used quantitative methods, such as Bradford assays, can be time-consuming, require extensive amounts of manual work from the user, and are limited to working with purified samples. With Alto’s fully automated system, users can easily generate 8 standard curves and estimate concentrations of up to 40 unknown samples using the quantitation assay.

This note will demonstrate how Alto accurately quantifies monoclonal antibodies (mAb) in serum specific to the H3N2 hemagglutinin (HA) protein at varying concentrations. H3N2 is a variant of the H1N1 Influenza virus and uses HA, a surface glycoprotein, for viral entry into the target cell. The receptor-binding domain of HA is a popular target for antibodies due to their ability to directly inhibit binding of the virus to the host cell receptor.

Figure 1: Activation of response channels with EDC/NHS from Nicoya’s Surfacing Kit, followed by immobilization of 50 μg/mL H3N2 HA antigen in Sodium Acetate pH 5.5 in the active channels and 50 μg/mL H1N1 NP antigen in Sodium Acetate pH 5.5 in the reference channels and blocking of sensors with 1 M Ethanolamine.