Extracellular Surface Potential Mapping by Scanning Ion Conductance Microscopy Revealed Transient Transmembrane Pore Formation Induced by Conjugated Polymer Nanoparticles

Abstract

In‐depth understanding of the biophysicochemical interactions at the nano–bio interface is important for basic cell biology and applications in nanomedicine and nanobiosensors. Here, the extracellular surface potential and topography changes of live cell membranes interacting with polymeric nanomaterials using a scanning ion conductance microscopy‐based potential imaging technique are investigated. Two structurally similar amphiphilic conjugated polymer nanoparticles (CPNs) containing different functional groups (i.e., primary amine versus guanidine) are used to study incubation time and functional group‐dependent extracellular surface potential and topographic changes. Transmembrane pores, which induce significant changes in potential, only appear transiently in the live cell membranes during the initial interactions. The cells are able to self‐repair the damaged membrane and become resilient to prolonged CPN exposure. This study provides an important observation on how the cells interact with and respond to extracellular polymeric nanomaterials at the early stage. This study also demonstrates that extracellular surface potential imaging can provide a new insight to help understand the complicated interactions at the nano–bio interface and the following cellular responses.

Interactions of Cell-Penetrating Peptide-Modified Nanoparticles with Cells Evaluated Using Single Particle Tracking

“…Surface modifications of nanoparticles with CPPs were shown to increase the interactions of the nanoparticles with the cell membrane. The internalization of PLGA nanoparticles and CPP solutions including penetratin and branched peptides is reported to take place within 1 h in cells − indicating that cell interactions occur within a short time. While the internalization of particles is generally well studied, the early cell interaction and thus the effect of surface decorating nanoparticles with CPPs have not been investigated.…”

Scanning Ion Conductance Microscopy Study Reveals the Disruption of the Integrity of the Human Cell Membrane Structure by Oxidative DNA Damage

“…The ΔV is defined as the potential difference between the potential values at the closest point and the farthest point from the cell surface in each ARS cycle. 27 The topography image resolution was ∼80 to 100 nm/pixel with the typical setting here. The time to acquire an image of 128 × 128 pixels was about 25 min.…”

“…0.90 mm, Sutter Instruments USA) were prepared by the pipette puller with the following parameters: HEAT = 805, FIL = 3, VEL = 40, DEL = 220, and PUL = 165. The formed double-barrel nanopipettes with the diameter of each nanopore around 170–200 nm were filled with the extracellular solution and used as the probe for SICM imaging. , It should be noted that the pore diameter is relatively bigger than the usual nanopore diameter below 100 nm size. The HEK293H cells show high secretion activities, which introduce a bigger noise in the measured ionic current during live cell imaging.…”

“…24 In our previous studies, we have utilized SICM to map and reveal submicrometer size changes of the cell membrane induced by cell-penetration polymer nanoparticles. 25 Based on SICM, a potential sensing probe can be added to qualitatively map the surface charge/ potential distribution of the cell membrane (see Figure 1), first introduced by Baker et al 26 We have used P-SICM to reveal both the topography and surface potential/charge changes induced by positively charged polymer nanoparticles 27 and elevated extracellular potassium concentration. 28 Here, our P-SICM studies found that the exposure to low concentrations of K 2 CrO 4 did not obviously affect surface charge/potential of the cell membrane, but resulted in a roughened cell membrane and the appearance of submicrometer-to micrometer-sized defects in the HEK293H cell membrane, indicating the disruption of the cell membrane structure.…”

Application of scanning ion conductance microscope in cell characterizations

“…此外, 细胞(淋巴细胞)的表面电荷还可反映 机体的免疫状态. 因此, 细胞局部表面电荷的可视化表 征及细胞表面电荷的不均匀性检测有利于深度了解细 胞功能 [90] . 目前, 虽然广泛用于细胞形貌表征的AFM 技术可检测细胞的表面电荷 [91,92] , 但由于AFM力作用 于探针 [93] , 力-距离曲线不易分析, 而且在高电解质浓 度(生理条件)下, AFM对表面电荷变得敏感, 当尖端到 基底距离压缩到1 nm或更小时, 细胞表面的电荷测量 很困难 [21] .…”