Conical nanopores enhance local nanopore electroporation for intracellular drug delivery.

Abstract

Localized nanopore electroporation improves intracellular delivery by concentrating membrane permeabilization at nanoscale cell-substrate interfaces. For nanopore-based substrates, the voltage fraction coupled to the cell-pore region contributes to local transmembrane potential (TMP), which determines the electroporation threshold. Here, we propose conical nanopores to enhance electric field focusing and facilitate electroporation. This effect was studied by varying the taper ratio of the nanopores from α = 1 to α = 4 through directional chemical etching to nanopore membranes. Lumped-parameter and finite-element simulations showed that this geometry doubled the estimated TMP under the same pulse condition. When performing electroporation to A549 cells, α = 4 structure achieved 62.1% propidium iodide (PI) delivery rate at a pulse voltage of 10 V, while ∼20 V was required to obtain a similar efficiency for α = 1. Besides, the PI delivery efficiency was greatly improved by increasing the taper ratio, from 55.3% to 80.4% for α = 4 at 15 V while maintaining 90.4% cell viability. In cisplatin electrochemotherapy, high-taper nanopores produced stronger growth inhibition and reduced 7-day outgrowth to over 34%. These results show that conical nanopore geometry improves voltage utilization and supports enhanced localized membrane permeabilization at lower applied voltages, and provide a viable strategy for practical applications such as drug delivery and transfection.