Microfluidic radiobioassays: a radiometric detection tool for understanding cellular physiology and pharmacokinetics

The investigation of molecular uptake and its kinetics in cells is valuable for understanding the cellular physiological status, the observation of drug interventions, and the development of imaging agents and pharmaceuticals. Microfluidic radiobioassays, or microfluidic radiometric bioassays, constitute a radiometric imaging-on-a-chip technology for the assay of biological samples using radiotracers. From 2006 to date, microfluidic radiobioassays have shown advantages in many applications, including radiotracer characterization, enzyme activity radiobioassays, fast drug evaluation, single-cell imaging, facilitation of dynamic positron emission tomography (PET) imaging, and cellular pharmacokinetics (PK)/pharmacodynamics (PD) studies. These advantages lie in the minimized and integrated detection scheme, allowing real-time tracking of dynamic uptake, high sensitivity radiotracer imaging, and quantitative interpretation of imaging results. In this review, the basics of radiotracers, various radiometric detection methods, and applications of microfluidic radiobioassays will be introduced and summarized, and the potential applications and future directions of microfluidic radiobioassays will be forecasted.