Isotachophoresis applied to chemical reactions

TL;DR

This review explores how isotachophoresis (ITP) enhances chemical reactions, especially in biomolecular contexts, by accelerating and automating processes across various platforms, with significant improvements in assay speed and sensitivity.

Contribution

It categorizes ITP-based reaction assays, reviews physical modeling and design principles, and highlights recent experimental advances and future challenges.

Findings

Up to 14,000-fold acceleration of nucleic acid assays

Enhanced immunoassays and bacterial detection

Physical modeling guides ITP assay optimization

Abstract

This review discusses research developments and applications of isotachophoresis (ITP) to the initiation, control, and acceleration of chemical reactions, emphasizing reactions involving biomolecular reactants such as nucleic acids, proteins, and live cells. ITP is a versatile technique which requires no specific geometric design or material, and is compatible with a wide range of microfluidic and automated platforms. Though ITP has traditionally been used as a purification and separation technique, recent years have seen its emergence as a method to automate and speed up chemical reactions. ITP has been used to demonstrate up to 14,000-fold acceleration of nucleic acid assays, and has been used to enhance lateral flow and other immunoassays, and even whole bacterial cell detection assays. We here classify these studies into two categories: homogeneous (all reactants in solution) and heterogeneous (at least one reactant immobilized on a solid surface) assay configurations. For each category, we review and describe physical modeling and scaling of ITP-aided reaction assays, and elucidate key principles in ITP assay design. We summarize experimental advances, and identify common threads and approaches which researchers have used to optimize assay performance. Lastly, we propose unaddressed challenges and opportunities that could further improve these applications of ITP.