Inverting a standard experiment sometimes produces different results

The standard experimental setup for measuring the cellular uptake of nanoparticles is to place cells in a well on a culture plate and cover them with culture medium containing nanoparticles. The assumption underlying these experiments is that the particles remain well-dispersed. But when a Washington University scientist turned cell cultures upside down, he discovered that this assumption doesn’t always hold. Some experiments preparing for the clinical use of nanoparticles may therefore need to be redone.