A Review of Advanced Impedance Biosensors with Microfluidic Chips for Single-Cell Analysis

Electrical impedance biosensors combined with microfluidic devices can be used to analyze fundamental biological processes for high-throughput analysis at the single-cell scale. These specialized analytical tools can determine the effectiveness and toxicity of drugs with high sensitivity and demonstrate biological functions on a single-cell scale. Because the various parameters of the cells can be measured depending on methods of single-cell trapping, technological development ultimately determine the efficiency and performance of the sensors. Identifying the latest trends in single-cell trapping technologies afford opportunities such as new structural design and combination with other technologies. This will lead to more advanced applications towards improving measurement sensitivity to the desired target. In this review, we examined the basic principles of impedance sensors and their applications in various biological fields. In the next step, we introduced the latest trend of microfluidic chip technology for trapping single cells and summarized the important findings on the characteristics of single cells in impedance biosensor systems that successfully trapped single cells. This is expected to be used as a leading technology in cell biology, pathology, and pharmacological fields, promoting the further understanding of complex functions and mechanisms within individual cells with numerous data sampling and accurate analysis capabilities.

A Rapid Single-Cell Antimicrobial Susceptibility Testing Workflow for Bloodstream Infections

Bloodstream infections are a significant cause of morbidity and mortality worldwide. The rapid initiation of effective antibiotic treatment is critical for patients with bloodstream infections. However, the diagnosis of bloodborne pathogens is largely complicated by the matrix effect of blood and the lengthy blood tube culture procedure. Here we report a culture-free workflow for the rapid isolation and enrichment of bacterial pathogens from whole blood for single-cell antimicrobial susceptibility testing (AST). A dextran sedimentation step reduces the concentration of blood cells by 4 orders of magnitude in 20–30 min while maintaining the effective concentration of bacteria in the sample. Red blood cell depletion facilitates the downstream centrifugation-based enrichment step at a sepsis-relevant bacteria concentration. The workflow is compatible with common antibiotic-resistant bacteria and does not influence the minimum inhibitory concentrations. By applying a microfluidic single-cell trapping device, we demonstrate the workflow for the rapid determination of bacterial infection and antimicrobial susceptibility testing at the single-cell level. The entire workflow from blood to categorical AST result can be completed in less than two hours.

A Microfluidic Array Device for Single Cell Capture and Intracellular Ca2+ Response Analysis Induced by Dynamic Biochemical Stimulus

A microfluidic array was constructed for trapping single cell and loading identical dynamic biochemical stimulation for gain a better understanding of Ca2+ signalling in single cells by applying extracellular dynamic biochemical stimulus. This microfluidic array consists of multiple radially aligned flow channels with equal intersection angles, which was designed by a combination of stagnation point flow and physical barrier. Numerical simulation results and trajectory analysis shown the effectiveness of this single cell trapping device. Fluorescent experiment results demonstrated the effects of flow rate and frequency of dynamic stimulus on the profiles of biochemical concentration which exposed on captured cells. In this array chip, the captured single cells in each trapping channels were able to receive identical extracellular dynamic biochemical stimuli which being transmitted from the entrance at the middle of the microfluidic array. Besides, after loading dynamic Adenosine Triphosphate (ATP) stimulation on captured cells by this device, consistent average intracellular Ca2+ dynamics phase and cellular heterogeneity were observed in captured single K562 cells. Furthermore, this device is able to be used for investigating cellular respond in single cells to temporally varying environments by modulating the stimulation signal in terms of concentration, pattern, and duration of exposure.

Application of Microfluidics in Single-cell Manipulation, Omics and Drug Development

Background: Cell heterogeneity exists among different tissues even in the same type of cells. Cell heterogeneity leads to a difference in cell size, functions, biological activity, and for cancer cells it causes different drug responses and resistance. Meanwhile, microfluidics is a promising tool for single-cell research to reveal cell heterogeneity. Method: Through literature research conducted over the past ten years on microfluidics, we summarize and introduce the application of microfluidics in single-cell separation and manipulation, featuring techniques such as acoustic manipulation, optical manipulation, single-cell trapping, and patterning, as well as single-cell omics including single-cell genomics, single-cell transcriptomics, single-cell proteome, single-cell metabolome, and drug development. Results: Microfluidics is a flexible, precise tool, and it is easy to integrate with different functions. Firstly, it can be used as an important tool to separate rare but important cells according to the cell`s biological or physical properties. Secondly, microfluidics can provide the possibility of single-cell omics. Thirdly, microfluidics can be used in drug development specifically in drug delivery and drug combination. Meanwhile, droplet microfluidics has gradually become the most powerful tool to encapsulate single-cells with other reagents for DNA, RNA, or protein analysis. Conclusion: Microfluidics is a robust platform technology which is able to accomplish rare cell separation, efficient single-cell omics analysis and provide a platform for drug development and drug delivery.

A microfluidic device enabling deterministic single cell trapping and release

Successful single-cell isolation is a pivotal technique for subsequent biological and chemical analysis of single cells. Although significant advances have been made in single-cell isolation and analysis techniques, most passive...

FINITE SIMULATIONS OF MICRO-PARTICLE SUPPORTING FOR SINGLE CELL TRAPPING IN MICROFLUIDIC SYSTEM

Finite element method (FEM) is the most widely used approach in the simulation of micro-nano devices before actual fabrication. Using simulation software, 2D and 3D structures of the device are designed, meshed, and then simulated to optimize their parameters. In this work, we modeled and simulated the hydrodynamic trapping of micro-particle (μP) representing for single-cell in the microfluidic system. Besides, the interaction between μP and fluid, the effect of flow velocity, and the pressure field variation for increasing the trapping efficiency were investigated. Besides, a fully understanding the behavior of micro-particle during the trapping process is exhibited. Based on the achieved results, the optimization of the design will be adjusted as a pre-step before being used for fabrication and experiment. The simulation results are valuable for designing and fabricating the microfluidic platform for single-cell research.

High throughput profiling drug response and apoptosis of single polar cells

The drug response of single polar cells was evaluated via single cell trapping on anisotropic microwells for tumor heterogeneity.