Tension Sensing Nanoparticles for Mechano-Imaging at the Living/ Nonliving Interface

ABSTRACT: Studying chemomechanical coupling at interfaces is important for fields ranging from lubrication and tribology to microfluidics and cell biology. Several polymeric macro- and microscopic systems and cantilevers have been developed to image forces at interfaces, but few materials are amenable for molecular tension sensing. To address this issue, we have developed a gold nanoparticle sensor for molecular tension-based fluorescence micro-scopy. As a proof of concept, we imaged the tension exerted by integrin receptors at the interface between living cells and a substrate with high spatial (<1 μm) resolution, at 100 ms acquisition times and with molecular specificity. We report integrin tension values ranging from 1 to 15 pN and a mean of ∼1 pN within focal adhesions. Through the use of a conventional fluorescence micro