Temperature Tolerance Electric Cell-Substrate Impedance Sensing for Joint Assessment of Cell Viability and Vitality

Microplate-based impedance and thermal sensing system for concurrent cell viability and counting analysis

Cell count and viability are critical parameters in biological research, drug discovery, and bioprocessing. Traditional methods for assessing these metrics often rely on destructive, end-point analyses. This research presents a novel multi-parameter sensing platform that enables concurrent analysis of cell viability and count in a microplate format. The platform combines thermal-based and impedance-based sensing to harness the distinct responses of these methods to variations in cell number and viability. Crucially, both techniques are influenced by cell viability and count, but to different degrees. This difference in sensitivity allows for the exploitation of both methods to independently assess these parameters. Thermal sensing primarily quantifies cell biomass, while impedance measurements are more sensitive to membrane integrity changes associated with cell viability. The integration of these sensing elements into a standard microwell format facilitates real-time and label-free measurements. Experiments with Saccharomyces cerevisiae cultures at various concentrations and viability states demonstrated the platform's capabilities. Multivariate regression models were developed to independently predict cell number and viability, achieving root mean square errors of 0.106 ×107 cells and 19.67% viability respectively. Notably, performance improved at higher cell concentrations, with viability prediction error reduced to 5.02%. This integrated approach shows promise for continuous, non-destructive monitoring of cell cultures, offering a cost-effective alternative to traditional end-point analysis methods. The platform's ability to provide real-time insights into cell population dynamics could significantly enhance various applications in biotechnology, including bioprocess optimization, drug screening, and toxicity testing. Furthermore, its compatibility with standard microplate formats facilitates easy integration into existing laboratory workflows.

Evaluation of Cancer Cell Invasion Ability Based on Electrochemical Impedance

Cancer metastasis is the leading cause of cancer-related deaths, with the ability of cancer cells to invade blood vessels or lymphatic systems, determining their metastatic potential. Therefore, the rapid and accurate assessment of cell invasiveness is crucial. Current methods, such as the Transwell assay and fluorescent labeling, are complex, invasive, and may disrupt the physiological state of live cells. In this study, we introduce an electrochemical impedance-based method for evaluating cancer cell invasiveness, combining Transwell and microfluidic technologies to monitor the invasion process in a dynamic environment. A stable microfluidic chip with 30 μm interdigital electrodes was developed, optimized for HeLa cell detection. We identified 1 kHz as the optimal frequency for achieving the maximum impedance resolution of cancer cell invasiveness. By correlating the impedance response of Zcells/Zno-cells with invasiveness, we established a reliable electrochemical model. This model was validated with a hydrogen peroxide cytotoxicity assay, showing a high correlation with optical staining and a minimal error of 1.89%, underscoring its potential for drug efficacy prediction. The proposed method offers rapid detection, low cost, and requires no manual intervention, making it an efficient and reliable tool for assessing cancer cell invasiveness in therapeutic research.

Cell viability assessment by using GelRed/SYTO 9-based double staining

Cell viability assessment plays a crucial role in biological research, pharmaceutical development, and toxicological identification. Here, we used GelRed, a sensitive and safer nucleic acid dye, to selectively label dead cells with red fluorescence (FL) thus distinguishing dead cells from live ones. Further more, the combined use of GelRed and SYTO 9 (another nucleic acid dye) enabled the clear differentiation in FL spectra between the two physiological statuses. The GelRed and SYTO 9 concentrations were optimized to obtain the highest FL ratio of dead to live cells. The GelRed/SYTO 9-based double staining could quantify the cell viability through flow cytometry analysis, with a good correlation between the detected and theoretical dead cell ratios. Compared with traditional prodium iodide (PI) staining, the GelRed/SYTO 9-based double staining showed high accuracy in quantifying dead cell of low levels. The as-developed staining method could be used in biomedical research to accurately measure the cytotoxic effect of various substances in living cells.

Study on Microfluidic Chip Flow Rate Uniformity for Cell Activity Detection

During the cell viability detection process inside a microfluidic chip, the more uniform the distribution of medium flow rates, the higher the accuracy of detection results. In order to achieve this goal, a multichannel microfluidic chip with uniform distribution of medium flow rates has been successfully designed. The multichannel microfluidic chip is designed with cell injection channels, vascular network-shaped medium injection channels, buffer zones, and a culture chamber. The medium flow rates inside culture chambers of the multichannel microfluidic chip and the common single-channel microfluidic chip are compared by COMSOL Multiphysics software and particle velocimetry experiment. The simulation and experimental results show that the medium flow rate distribution inside the culture chamber of the multichannel microfluidic chip is more uniform and changes more smoothly. When the medium perfusion flow rate is 0.5 μL/min, the maximum flow rate difference inside the culture chamber of the single-channel microfluidic chip is more than 13 times that of the multichannel microfluidic chip. Therefore, the multichannel microfluidic chip can ensure a uniform supply of medium inside the culture chamber, which is beneficial to improve the accuracy of cell viability detection.

A Detection Method for Crop Fungal Spores Based on Microfluidic Separation Enrichment and AC Impedance Characteristics

The timely monitoring of airborne crop fungal spores is important for maintaining food security. In this study, a method based on microfluidic separation and enrichment and AC impedance characteristics was proposed to detect spores of fungal pathogens that cause diseases on crops. Firstly, a microfluidic chip with tertiary structure was designed for the direct separation and enrichment of Ustilaginoidea virens spores, Magnaporthe grisea spores, and Aspergillus niger spores from the air. Then, the impedance characteristics of fungal spores were measured by impedance analyzer in the enrichment area of a microfluidic chip. The impedance characteristics of fungal spores were analyzed, and four impedance characteristics were extracted: absolute value of impedance (abs), real part of impedance (real), imaginary part of impedance (imag), and impedance phase (phase). Finally, based on the impedance characteristics of extracted fungal spores, K-proximity (KNN), random forest (RF), and support vector machine (SVM) classification models were established to classify the three fungal spores. The results showed that the microfluidic chip designed in this study could well collect the spores of three fungal diseases, and the collection rate was up to 97. The average accuracy of KNN model, RF model, and SVM model for the detection of three disease spores was 93.33, 96.44 and 97.78, respectively. The F1-Score of KNN model, RF model, and SVM model was 90, 94.65, and 96.18, respectively. The accuracy, precision, recall, and F1-Score of the SVM model were all the highest, at 97.78, 96.67, 96.69, and 96.18, respectively. Therefore, the detection method of crop fungal spores based on microfluidic separation, enrichment, and impedance characteristics proposed in this study can be used for the detection of airborne crop fungal spores, providing a basis for the subsequent detection of crop fungal spores.