Aqueous Two-Phase System Rehydration of Antibody-Polymer Microarrays Enables Convenient Compartmentalized Multiplex Immunoassays.

Multiplex immunoassays are rapidly increasing in popularity due to the offered advantages of increased throughput and decreased sample volume requirements. However, a major weakness inherent to multiplex enzyme-linked immunosorbent assays (ELISA) is generation of false signals through reagent-driven cross-talk. Typically, multiplex platforms necessitate bath application of antibody cocktails, increasing probability of nonspecific antibody binding, especially when multiplexing large numbers of analytes. Aqueous two-phase systems (ATPS) exploiting the phase-separating polymers poly(ethylene) glycol (PEG) and dextran (DEX) have been used to compartmentalize antibodies and prevent cross-talk in multliplex, plate-based ELISA. However, the resulting protocol is tedious and lengthy, and requires too many user steps to be practical for widespread use. Here, we report an improved, user-friendly, cross-talk-free multiplex ELISA method in which dehydrated arrays of colocalized capture and detection antibodies in DEX are prepared on multiwell plates. Addition of a PEG-based sample buffer rehydrates antibody/DEX droplets for analysis. In this report, we demonstrate rehydrated ATPS components for multiplex ELISA retain the ability to compartmentalize antibodies and prevent cross-talk, while analytes in sample buffer partition into rehydrated DEX droplets for analysis. Utility of this method was demonstrated through successful quantitative analysis of five inflammatory cytokines in lipopolysaccharide-stimulated ThP-1 cell culture supernatant.