Dependence of Impedance of Embedded Single Cells on Cellular Behaviour

Quantification of non-alcoholic fatty liver disease progression in 3D liver microtissues using impedance spectroscopy

Non-alcoholic fatty liver disease (NAFLD) has become a global pandemic. However, a pharmacological cure has not been approved for NAFLD treatment. The greatest barriers to the development of new treatments are the ambiguous criteria among the NAFLD stages and the lack of quantitative methodologies for its disease assessment in a translatable preclinical model. In this study, we developed impedance assessment systems to quantify NAFLD progression in three-dimensional (3D) liver microtissue (hMT). The hMT model undergoing NAFLD represents clinical-like characteristics for a range of stages, such as lipid accumulation, cell ballooning, and stiffening. Each stage can be quantitatively assessed by an impedance system with microchannels under constant or dynamic pressure, depending on the relevant mechanical and morphological changes used in the clinical assessment of NAFLD. We determined a correlation between the impedance parameters and pathophysiological characteristics, such as gap widening and cytoplasmic deformation associated with NAFLD progression using bioimpedance simulation, showing hMTs struggling to return to normal states. In addition, we identified the relative stiffness to assess fibrogenesis from the correlation of resistance change and elongation length into the smaller channel of hMTs. We hope this methodology will have a significant impact on drug development by facilitating improved NAFLD assessment.

Making a big thing of a small cell--recent advances in single cell analysis

Single cell analysis is an emerging field requiring a high level interdisciplinary collaboration to provide detailed insights into the complex organisation, function and heterogeneity of life. This review is addressed to life science researchers as well as researchers developing novel technologies. It covers all aspects of the characterisation of single cells (with a special focus on mammalian cells) from morphology to genetics and different omics-techniques to physiological, mechanical and electrical methods. In recent years, tremendous advances have been achieved in all fields of single cell analysis: (1) improved spatial and temporal resolution of imaging techniques to enable the tracking of single molecule dynamics within single cells; (2) increased throughput to reveal unexpected heterogeneity between different individual cells raising the question what characterizes a cell type and what is just natural biological variation; and (3) emerging multimodal approaches trying to bring together information from complementary techniques paving the way for a deeper understanding of the complexity of biological processes. This review also covers the first successful translations of single cell analysis methods to diagnostic applications in the field of tumour research (especially circulating tumour cells), regenerative medicine, drug discovery and immunology.

Single-cell resolution diagnosis of cancer cells by carbon nanotube electrical spectroscopy

We report the use of vertically aligned carbon nanotubes (VACNTs) as electrical endoscopes (biosensors) for cancer metastatic diagnosis at single-cell resolution. The device is based on direct signal extraction by means of vertically aligned conductive carbon nanotubes from a live cell membrane, which has been disrupted during carcinogenesis at its primary and progressive stages. The value of this electrical disruption depends on the cancer metastatic grade. In addition, the electrical resonance behavior of the cell, halted during cancer progression, could be monitored as a new cancer diagnostic profile. By taking a second derivative of the cell impedance with respect to applied frequency, we have arrived at a new spectroscopy tool for distinguishing cancerous stages of colon and breast carcinoma cells.

Utilization of Electrochemical Sensors and Biosensors in Biochemistry and Molecular Biology

A special issue of Sensors entitled “Utilization of Electrochemical Sensors and Biosensors in Biochemistry and Molecular Biology” has been prepared over a period of three years. In this Editorial Note we would like to highlight one of the possible directions for electrochemical sensor and biosensor research resulting from the ideas of Czechoslovakian Nobel Prize winner Jaroslav Heyrovsky and his colleague Rudolf Brdicka.