Dynamic Control of Nanoprecipitation in a Nanopipette

Abstract

Studying the earliest stages of precipitation at the nanoscale is technically challenging but quite valuable as such phenomena reflect important processes such as crystallization and biomineralization. Using a quartz nanopipette as a nanoreactor, we induced precipitation of an insoluble salt to generate oscillating current blockades. The reversible process can be used to measure both kinetics of precipitation and relative size of the resulting nanoparticles. Counter ions for the highly water-insoluble salt zinc phosphate were separated by the pore of a nanopipette and a potential applied to cause ion migration to the interface. By analyzing the kinetics of pore blockage, two distinct mechanisms were identified: a slower process due to precipitation from solution, and a faster process attributed to voltage-driven migration of a trapped precipitate. We discuss the potential of these techniques in studying precipitation dynamics, trapping particles within a nanoreactor, and electrical sensors based on nanoprecipitation.

The Influence of Divalent Anions on the Rectification Properties of Nanofluidic Diodes: Insights from Experiments and Theoretical Simulations

“…Even though the incidence of geometry and surface charge in the rectification behavior of nanopores has been thoroughly studied, there is still a lack of understanding of fundamental issues like the importance of the nature of the electrolyte in the current transport. Despite existing previous works that reported the use of different ions in the electrolyte solution, most of these reports studied the effect of monovalent and divalent cations . The analysis of those results was not so straightforward, because the strong interactions between the inner surface of the nanopores, normally bearing a net negative charge, and the cations, were also associated with nanoprecipitation and charge reversal effects.…”

“…Despite existing previous works that reportedt he use of different ions in the electrolyte solution, most of these reports studied the effect of monovalent and divalentc ations. [25][26][27][28][29][30][31] The analysis of those resultsw as not so straightforward, because the strong interactions between the inner surfaceo ft he nanopores, normallyb earing an et negative charge, and the cations, were also associated with nanoprecipitation and charge reversal effects. We believe it is necessary to understand the influence of the transported ions nature on the transport properties of the rectifying nanofluidic devices.…”

Electrochemical Control of Calcium Carbonate Crystallization and Dissolution in Nanopipettes

“…Simultaneously, the ionic current through the end of the nanopipette is sensitive to these events and can be monitored with high time resolution. This approach builds on earlier work that considered the crystallization of zinc phosphate in a nanopipette, showing that the current through the nanopipette was sensitive to growth events and that this process could be manipulated through alteration of the local electric field . Our work develops and advances this methodology significantly and puts it on a quantitative footing.…”

Reversible thrombin detection by aptamer functionalized STING sensors

“…As a nanopipette approaches a surface, the ionic current through the pipette will decrease due to “current squeezing,” a well known effect, exploited to great benefit in scanning ion conductance microscopy (SICM) (Hansma et al 1989). Besides sensing, nanopipette based platforms have been used to control chemical reactions at the nanoscale (Vilozny et al 2011), investigate single-molecule biophysics (Clarke et al 2005), for the controlled delivery of molecules inside a single cell (Laforge et al 2007), and to image cells at the nanoscale (Klenerman and Korchev 2006). …”