Tunable Resistive Pulse Sensing (TRPS) monitors current flow through a tunable nanopore. Particles crossing the nanopore cause transient changes in the flow of an ionic current, which can be detected and analysed via the resulting blockades. Each particle size is determined for individual particles; blockade magnitude is proportional to particle size, and particle concentration is calculated from the particle flow rate measured at several different applied pressures. Zeta potential (a measure of the effective surface charge) is derived by measuring electrophoretic mobility, which is calculated based on the speed at which the particle traverses the nanopore. For those looking to gain real insights into the size and concentration, or size and zeta potential, of particles in their sample, Tunable Resistive Pulse Sensing (TRPS) is a far superior technique. Unlike Dynamic Light Scattering (DLS), which is an ensemble technique that measures the average intensity of light scattered by particles in a solution, TRPS is a single-particle analytical method and uses more direct measurements of physical characteristics. This allows you to detect subtle differences between subpopulations of particles in your sample – differences which may be critical indicators of sample stability, aggregation, or differences in drug loading efficiency. With DLS, these subtle differences can easily be missed. TRPS enables high-resolution particle measurement (40 nm to > 11 µm), allowing a wide range of particle types to be characterised. Unlike DLS, TRPS measurements are independent of the particle or dispersant’s optical properties, allowing you to confidently measure samples with heterogenous optical densities. Given its ability to accurately and reproducibly resolve samples to a high level of resolution, Tunable Resistive Pulse Sensing (TRPS) lends itself to a wide range of applications across biological and pharmaceutical research and development. TRPS has filled the unmet need for precise characterisation for a range of particle types. In the context of measuring exosomes and other extracellular vesicles (EVs), TRPS is commonly used to identify differences in EV concentration under different physiological conditions, verify the presence of EVs via measurements of particle size distribution, and identify changes to zeta potential under different conditions (e.g. studies of EV storage conditions). In nanomedicine, TRPS has far-reaching applications, enabling stability and characterisation studies across the development of monoclonal antibodies, lipid nanoparticles, virus-like particle vaccines, and virus preparations.
