Experiments were conducted to confirm SOMAmer® reagent specificity by enrichment in serum from elderly subjects (>65 years, male n=1 and female n=1, purchased from commercial vendor) followed by measurement using data dependent analysis (DDA). Non-specific binding was assessed in the biological matrix by comparing target protein spectral counts in the respective enrichment to pull down using a reagent generated against the bacterial protein CysH. A positive hit was defined as target protein detection with a minimum of 2 spectral counts and signal over CysH background greater than 10X (if applicable).