Abstract

Since its invention in the 1970s, the enzyme-linked immunosorbent assay (ELISA) has served as the "gold-standard" for blood and plasma protein biomarker quantification. However, ELISAs require significant amounts of sample preparation entailing multiple reagent additions, incubations, and washing steps, limiting their clinical usefulness in the context of diagnosis and prognosis of rapidly evolving medical conditions. In this work, we describe the instant ELISA biosensor platform, a probe that can be exposed directly to blood or other biological samples and quantifies protein biomarkers within 15 minutes. The sensor leverages a novel affinity reagent termed monolithic dual-antibody clamp (MDAC) which preserves the specificity, sensitivity, and generalizability of ELISA while also enabling rapid analysis of unprocessed blood and other complex matrices. Using MDAC in chicken media, we demonstrate picomolar quantification of the inflammatory marker tumor necrosis factor alpha (TNF), as well as monocyte chemotactic protein (MCP)-1, a useful prognostic indicator of cytokine release syndrome (CRS) during chimeric antigen receptor (CAR) T-cell immunotherapy. Finally, we demonstrate MCP-1 quantification in plasma samples from patients who had undergone CAR T-cell treatment.