Abstract: Provided are methods of detecting a biomolecule of interest in a sample. In certain embodiments, the methods comprise contacting the sample with a biolayer interferometry (BLI) sensor, the BLI sensor comprising a capture antigen specific for the biomolecule affixed to the BLI sensor, wherein a wavelength shift detected by the BLI sensor indicates the presence of the biomolecule of interest in the sample. The methods may further comprise contacting the BLI sensor with a detecting reagent (e.g., an antibody or the like) specific for the biomolecule of interest, where the detecting reagent is conjugated to a colloidal gold particle or other signal enhancing molecule. In certain embodiments, the biomolecule of interest is an antibody specific for a viral antigen, e.g., a SARS-CoV-2 antigen-specific antibody, or the like. Also provided are BLI sensors and kits that find use, e.g., in practicing the methods of the present disclosure.