Profiling Live Neuronal Cell Membrane Integrity with Microfluidic Electrorotation

Cell membrane damage is deeply connected to many diseases, including neurodegenerative disorders such as Parkinson’s disease. The plasma membrane controls transport, signaling, ion balance, and cellular homeostasis, so even subtle changes in membrane integrity can have major biological consequences. The challenge is that many common methods for studying membrane damage are either indirect, low-throughput, endpoint-based, or limited to localized regions of the cell surface. Dye-based assays, for example, often infer damage from permeability or metabolic changes rather than directly measuring the physical state of the whole membrane. Patch clamp and microscopy-based methods can provide rich information, but they are often slow, technically demanding, or difficult to scale for single-cell measurements in live cells. Microfluidic technology, however, has a solution. In this article, the research address this gap by developing a microfluidic chip that can monitor whole-cell membrane integrity in live neuronal cells using label-free dielectric measurements. The biological model they chose is especially relevant to Parkinson’s disease: different aggregated forms of α-Synuclein, a protein strongly associated with neurodegeneration and membrane disruption.

The authors propose a microfluidic electrorotation platform that measures membrane integrity at the single-cell level by analyzing how live neuronal cells rotate in a controlled electric field. The key idea is that a cell’s rotation depends on its dielectric properties, including membrane capacitance. When membrane integrity is compromised, the electrorotation spectrum shifts, allowing the researchers to extract changes in plasma membrane electrical capacitance. This gives them a way to compare how different α-Synuclein species affect the entire membrane surface of individual live cells over time. Their microfluidic device combines microfluidic flow, 3D microelectrodes, dielectrophoretic trapping, and optical imaging, enabling continuous analysis of up to 30 live neuronal cells per hour. Compared with bulk assays, this microfluidic design preserves single-cell resolution and can reveal heterogeneous membrane responses that might otherwise be hidden in population-level measurements.

The microfluidic device was microfabricated around five electrorotation microcages, each formed by three-dimensional platinum electrodes. The electrodes were 80 µm in diameter and spanned the full 50 µm height of the channel, which is important because 3D electrodes create a more uniform electric field across the channel height than planar electrodes. This improves cell capture and measurement reproducibility because cells experience more consistent dielectrophoretic forces regardless of their vertical position in the channel. The microfluidic device also included a Galton array upstream of the measurement region.

For microfabrication of the microfluidic chips, they used a glass wafer, patterned Ti/Pt/Ti metal layers for electrical connections, SiO₂ insulation, SU-8 scaffolds for the 3D electrode structures, and PDMS bonding to seal the microfluidic channel. In operation, M17 human neuroblastoma cells were suspended in a low-conductivity buffer with controlled osmolarity. Cells were introduced into the chip using pressure-driven flow. When a single cell reached a microcage, the flow was stopped and a dielectrophoretic trapping field centered the cell inside the cage. The researchers then applied a rotating electric field with a 90° phase shift between neighboring electrodes. Each cell was imaged while the field frequency was swept across 21 frequencies between 15 kHz and 2.14 MHz, producing an electrorotation spectrum for that individual cell. The spectra were fitted using a single-shell cell model to extract membrane electrical capacitance.

The biological experiments focused on different forms of human wild-type α-Synuclein: monomers, oligomers, fibrils, and a mixture of monomers and fibrils. M17 cells were incubated with these species for 0, 3, or 6 hours before measurement. The authors also used Miltefosine and Lovastatin as membrane-compromising drug controls. Cell viability was monitored directly on-chip with Calcein AM and ethidium homodimer-1 so that dead or membrane-compromised cells could be excluded from the live-cell datasets. Before electrorotation measurements, the authors confirmed that α-Synuclein species were present on the cell surface using fluorescently labeled monomers and fibrils. 

The first key result was technical validation. The Galton array improved microfluidic device performance by enriching single cells in the measurement region and reducing clogging from cell clusters. The device reached a maximum throughput of ~30 cells per hour, compared with ~20 cells per hour for the version without the Galton array. This is still not a high-throughput flow cytometer, but it is a meaningful step for single-cell electrorotation because each measurement extracts a biophysical membrane parameter rather than a simple fluorescence or scattering readout. The second key result was that the platform could detect membrane damage caused by known membrane-compromising compounds.

Overall, this study presents a microfluidic electrorotation platform for measuring whole-membrane integrity in live neuronal cells with single-cell resolution. Its main strength is that it converts subtle membrane damage into a quantitative dielectric readout, membrane electrical capacitance, while keeping the cells alive and measured under controlled flow conditions. The work shows how 3D electrodes, dielectrophoretic trapping, and single-cell electrorotation can be combined into a practical microfluidic platform for studying membrane-related toxicity. Beyond Parkinson’s disease, the same microfluidic approach could be useful for studying other protein aggregates, membrane-targeting toxins, drug-induced membrane effects, or early biophysical changes that occur before clear cytotoxicity appears.

 

Figures are reproduced from Ryser, T., Krichene, A., Marchi, N. et al. A microfluidic platform for whole-membrane integrity profiling in live neuronal cells. Microsyst Nanoeng 12, 225 (2026). https://doi.org/10.1038/s41378-026-01209-0 under a Creative Commons Attribution Attribution 4.0 International

Read the original article: A microfluidic platform for whole-membrane integrity profiling in live neuronal cells

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