Capacitive coupling increases the accuracy of cell-specific tumour disruption by electric fields

Rapid Cryptococcus electroporated-lysis and sensitive detection on a miniaturized platform

Fast and accurate detection of Cryptococcus and precise differentiation of its subtypes is of great significance in protecting people from cryptococcal disease and preventing its spread in populations. However, traditional Cryptococcus identification and detection techniques still face significant challenges in achieving high analysis speed as well as high sensitivity. In this work, we report an electric microfluidic biochip. Compared to conventional methods that take several hours or even a day, this chip can detect Cryptococcus within 20 min, and achieve its maximum detection limit within 1 h, with the ability to differentiate between the Cryptococcus neoformans (NEO) and rare Cryptococcus gattii (GAT) efficiently, which accounts for nearly 100%. This device integrated two functional zones of an electroporation lysis (EL) zone for rapid cell lysis (<30 s) and an electrochemical detection (ED) zone for sensitive analysis of the released nucleic acids. The EL zone adopted a design of microelectrode arrays, which obtains a large electric field intensity at the constriction of the microchannel, addressing the safety concerns associated with high-voltage lysis. The device enables a limit of detection (LOD) of 60 pg/mL for NEO and 100 pg/mL for GAT through the modification of nanocomposites and specific probes. In terms of the detection time and sensitivity, the integrated microfluidic biochip demonstrates broad potential in Cryptococcus diagnosis and disease prevention.

Recent Advances in Microscale Electroporation

Electroporation (EP) is a commonly used strategy to increase cell permeability for intracellular cargo delivery or irreversible cell membrane disruption using electric fields. In recent years, EP performance has been improved by shrinking electrodes and device structures to the microscale. Integration with microfluidics has led to the design of devices performing static EP, where cells are fixed in a defined region, or continuous EP, where cells constantly pass through the device. Each device type performs superior to conventional, macroscale EP devices while providing additional advantages in precision manipulation (static EP) and increased throughput (continuous EP). Microscale EP is gentle on cells and has enabled more sensitive assaying of cells with novel applications. In this Review, we present the physical principles of microscale EP devices and examine design trends in recent years. In addition, we discuss the use of reversible and irreversible EP in the development of therapeutics and analysis of intracellular contents, among other noteworthy applications. This Review aims to inform and encourage scientists and engineers to expand the use of efficient and versatile microscale EP technologies.

Advantages and limitations of various treatment chamber designs for reversible and irreversible electroporation in life sciences

The fundamental mechanisms of pulsed electric fields on biological cells are not yet fully elucidated, though it is apparent that membrane electroporation plays a crucial role. Little is known about treatment-chamber-specific effects, and systematic studies are scarce. Thus, the present study evaluates the (dis-)advantages of various treatment chamber designs for liquid applications at differing scales. Three chambers, namely parallel plate microfluidic (V̇: 0.1 ml/min; titanium electrodes), co-linear meso (V̇: 5.0 ml/min; stainless steel electrodes), and co-linear macro (V̇: 83.3 ml/min; stainless steel electrodes) chambers, were studied. Electroporation effects on Escherichia coli in media with 0.1-10.0 mS/cm were evaluated by plate counts and flow cytometry at 8, 16, and 20 kV/cm. For the microfluidic chamber, predominantly irreversible electroporation (2.5 logs₁₀ reductions) was seen at 0.1 mS/cm, while high irreversible electroporation (4.2 logs₁₀ reductions) at 10.0 mS/cm was observed for the macro chamber. The meso chamber indicated a similar trend towards increased conductivity, even though only low inactivation levels were present. Variation in conductivity and electrode configuration or area likely induces effects resulting in distinct electroporation levels, as observed for the micro and macro chamber. Suitable application scenarios, depending on targeted electroporation effects, were suggested.