A Broken Tip Allows a Better Trip: Translocation of Gold Nanoparticles Clusters through a Nanopipette

Nanopipette analysis is a sensitive sensing technology depending on the application of a potential to generate an ionic current at the orifice. Analytes such as DNA, proteins, and vesicles can be driven by the electric field inside the nanopipette, leading to detectable current blockage. However, it remains challenging to translocate negatively charged gold nanoparticles (AuNPs) through a conventional sharp nanopipette filled with symmetric physiological buffer. In this work, we introduce a strategy to drive the AuNPs out of the nanopipette tip conveniently without inner-wall functionalization. We intentionally break the nanopipette tip to change the geometry of orifice. Compared with intact nanopipettes, translocation events of AuNPs are significantly increased and detectable upon using nanopipettes with a broken-tip. This allows us to gain valuable insights into the driving force and translocation behaviour of AuNPs in nanopipettes with short necks and irregular edge at the tip. Our findings demonstrate a simple and effective strategy for AuNPs detection by nanopipettes and highlight the important role of tip geometry in pressure-assisted nanoparticle transport.