Tracking cell-nanoparticle interactions.

Nanoparticles are highly attractive tools for future biomedical applications. Essential steps towards using nanoparticles in living organisms include the development of strategies for a defined nanoparticle uptake by the cell, the availability of appropriate particle tracking methods and the design of nanoparticles with low cytotoxicity. Optical tweezers are versatile tools to study the interaction between particles and cells with nanometre, piconewton and microsecond resolution and they have proven capable of trapping and tracking individual nanoparticles in three dimensions. This minireview presents recent achievements for the usage of nanoparticles in in vivo studies and discusses how optical tweezers can be employed to quantify cell-nanoparticle interactions at the single particle level.