The feasibility of using quartz nanopipets as simple and cost-effective Coulter counters for calibration-less quantitation and sizing of nanoparticles by resistive pulsing sensing (RPS) was investigated. A refined theory was implemented to calculate the size distribution of nanoparticles based on the amplitude of resistive pulses caused by their translocation through nanopipets of known geometry. The RPS provided diameters of monodisperse latex nanoparticles agreed within the experimental error with those measured by using scanning electron microscopy (SEM), dynamic light scattering (DLS), and nanoparticle tracking analysis (NTA). The nanopipet-based counter, by detecting individual nanoparticles, could resolve with similar resolution as SEM mixtures of monodisperse nanoparticles having partially overlapping size distributions, which could not be discriminated by DLS or NTA. Furthermore, by calculating the hydrodynamic resistance of the nanopipets and consequently the volume flow through the tip enabled for the first time the calibration-less determination of nanoparticle concentrations with nanopipets. The calibration-less methodology is applied to sizing and quantitation of inactivated poliovirus of ∼26 nm diameter, which is the smallest size spherical shape virus ever measured by resistive pulse sensing.
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