Bio-nano Science: Better Metrics Would Accelerate Progress

An early step of evaluating a nanomaterial’s potential for biological applications is investigating its interactions with cells and biological fluids. These experiments generate complex data, which are summarized and analyzed through the use of metrics. Choosing appropriate metrics is thus critical to build a foundation for nanomaterial research. Unfortunately, several widely used metrics in the bio-nano scientific literature have significant issues and may not be delivering their intended insight. This perspective will label and discuss three problematic metrics in wide use within the field: Percentage Cell Association, used to measure the interaction strength between a cell and a nanoengineered material; Internalization Factor, used to measure the ability of a cell to internalize a nanoengineered system; and Detected Protein Abundance, used to analyze the composition of proteins that adsorb to a nanoengineered surface. We review the origin of each metric and explain why each fails to deliver the intended insight in the domain of bio-nano experiments. Finally, for each metric, we present alternative metrics that deliver the necessary insight while imposing little (or no) additional experimental burden. We hope that this perspective will increase the use of better metrics, improve reporting, and ultimately aid the transition of bio-nano science to a more quantitative field