Characterizations of nanospheres and nanorods using resistive-pulse sensing

Nanoparticles, such as colloids, liposomes, and extracellular vesicles, have important roles in a wide range of processes and applications. The detection and characterization of nanoparticles remain technological hurdles because of the small size of nanoparticles, especially when they are heterogeneous. Resistive-pulse sensing technology measures nanoparticles on a single-particle basis. We investigate multiple parameters, including shape and size of the nanoparticles and pores, affecting the transmembrane, blockade of ion current, or the resistive pulse. Finite-element simulations and experimental results agreed reasonable well with each other when monodisperse carboxylated polystyrene nanospheres were used. Compared to using a cylindrical pore, resistive pulses of larger magnitudes were generated using a conical pore of the same diameter. In addition, analyses of the resistive pulse provided information on the shape of nanoparticles, such as spheres or cylinders. This methodology, we believe, open opportunities to improve the characterization of nanoparticles.