Towards Nanomechanical Properties from Pipette Ion Currents

Abstract

Recent studies have correlated biological functions and diseases of various organs and tissues in the human body with their mechanical properties. In addition, interest in extracellular vesicles has surged as they have been found to play a crucial role in intercellular communications and regulatory functions. Both developments have fueled interest in the field of nanoscale biomechanics. A recently-developed technique called microaspiration (MA), which characterizes the mechanical properties of ‘soft’ particles, is well-suited for this task. MA operates by applying a negative pressure to aspirate samples through a micropipette (translocation) while monitoring both optical and electrical (ion current) data. Both sets of data are then used to derive mechanical properties by applying appropriate models. It has been demonstrated that MA can be used to derive mechanical properties from translocation events for both biological and polymer samples. To translate the technique down to the nanoscale an extensive and systematic study is required. As such, polydimethylsiloxane (PDMS) emulsions are excellent standard test samples due to their well-known material properties, and their tunable size range which covers both microscale and nanoscale. Results from MA experiments can also be correlated with those derived from colloidal probe atomic force microscopy (AFM). This comparative study aims to comprehensively adapt this mechanical characterization tool to the nanoscale.