NULISA: a novel proteomic liquid biopsy platform with attomolar sensitivity and high multiplexing.

The blood proteome holds great promise for precision medicine but poses daunting challenges due to the low abundance of the majority of plasma proteins and the vast dynamic range across the proteome. We report the development and validation of a novel proteomic analysis technology - NUcleic acid Linked Immuno-Sandwich Assay (NULISA™) - that incorporates a dual capture and release mechanism to suppress the assay background to the minimum, thus drastically improving the signal-to-noise ratio. NULISA improves the sensitivity of the proximity ligation assay by over 10,000-fold to the attomolar level, which is enabled by antibody-conjugated DNA sequences that mediate the purification of immunocomplexes and contain target-and sample-specific barcodes for next-generation sequencing-based, highly multiplexed analysis. To demonstrate its performance and utility, we developed a 200-plex NULISA targeting 124 cytokines and chemokines and 80 other immune response-related proteins that demonstrated superior sensitivity for detecting low-abundance proteins and high concordance with other immunoassays. The ultra-high sensitivity enabled the detection of previously difficult-to-detect but biologically important, low-abundance biomarkers in patients with autoimmune diseases and COVID-19. Fully automated NULISA uniquely addresses longstanding challenges in the proteomic analysis of liquid biopsy samples and makes broad and in-depth proteomic analysis accessible to the general research community and future diagnostic applications.