An emerging micro-scale immuno-analytical diagnostic tool to see the unseen. Holding promise for precision medicine and P4 medicine.

Over the years, analytical chemistry and immunology have contributed significantly to the field of clinical diagnosis by introducing quantitative techniques that can detect crucial and distinct chemical, biochemical and cellular biomarkers present in biosamples. Currently, quantitative two-dimensional hybrid immuno-analytical separation technologies are emerging as powerful tools for the sequential isolation, separation and detection of protein panels, including those with subtle structural changes such as variants, isoforms, peptide fragments, and post-translational modifications. One such technique to perform this challenging task is immunoaffinity capillary electrophoresis (IACE), which combines the use of antibodies and/or other affinity ligands as highly selective capture agents with the superior resolving power of capillary electrophoresis. Since affinity ligands can be polyreactive, i.e., binding and capturing more than one molecule, they may generate false positive results when tested under mono-dimensional procedures; one such application is enzyme-linked immunosorbent assay (ELISA). IACE, on the other hand, is a two-dimensional technique that captures (isolation and enrichment), releases, separates and detects (quantification, identification and characterization) a single or a panel of analytes from a sample, when coupled to one or more detectors simultaneously, without the presence of false positive or false negative data. This disruptive technique, capable of preconcentrate on-line results in enhanced sensitivity even in the analysis of complex matrices, may change the traditional system of testing biomarkers to obtain more accurate diagnosis of diseases, ideally before symptoms of a specific disease manifest. In this manuscript, we will present examples of the determination of biomarkers by IACE and the design of a miniaturized multi-dimensional IACE apparatus capable of improved sensitivity, specificity and throughput, with the potential of being used as a point-of-care instrument and holding promise for precision medicine and P4 medicine.