Development of a Lateral Flow Assay for Bevacizumab Using an Anti-Idiotype DNA Aptamer as a Capture Molecule

We developed a point-of-care testing method based on a lateral flow assay for bevacizumab, using an anti-idiotypic DNA aptamer as the capture molecule. Bevacizumab loaded onto the sample pad on the assay strip bound to the red-colored aptamer-modified gold nanoparticles (AuNPs) in the conjugation pad and then migrated into the developing zone. The AuNPs bound to bevacizumab were trapped by protein A on the test spot. In contrast, excess amounts of unreacted AuNPs on the control spot, confirming that they migrated correctly. The assay strips enabled analysis within 20 min after adding the sample, and bevacizumab was quantified by photographing the colored areas with a smartphone and analyzing the images. The assay kit was capable of quantifying bevacizumab in the range of 0–200 μg/mL in Avastin diluent and bevacizumab-spiked human serum samples. This assay method enables on-site analysis of bevacizumab concentrations with a simple operation and without special analytical apparatus.