Optical Detection of Interleukin-6 using Liquid Janus Emulsions using Hyperthermophilic Affinity Proteins

Michelle Chen, Elliot I. Corless, Bevin P. Engelward, Timothy M. Swager

Link to Paper: https://pubs.acs.org/doi/full/10.1021/acsomega.4c03959

Agglutination of liquid Janus emulsions creates optical signals that can be detected and quantified. This study reports the detection and quantitation of Interleukin-6 (IL-6) using emulsions functionalized at the water-organic interface with engineered hyperthermophilic affinity proteins (rcSso7d) derived from thermophilies. Two rcSso7d affinity protein variants were synthesized with a non-canonical azide-functionalized amino acid and detection schemes were compared using one or both binders. The two proteins recognize different epitopes, which can enable simultaneous binding to monomeric IL-6 for agglutination. It is noteworthy that the rsSso7d protein variants, in addition to having superior thermal stability and facile recombinant synthesis in E. coli, these variants show superior performance when compared to commercial antibodies for IL-6.