A portable standalone wireless electric cell-substrate impedance sensing (ECIS) system for assessing dynamic behavior of mammalian cells

Reproducibility analysis of bioimpedance-based self-developed live cell assays

Bioimpedance spectrum (BIS) measurements have a great future in in vitro experiments, meeting all the requirements for non-destructive and label-free methods. Nevertheless, a real basic research can provide the necessary milestones to achieve the success of the method. In this paper a self-developed technology-based approach for in vitro assays is proposed. Authors invented a special graphene-based measuring plate in order to assess the high sensitivity and reproducibility of introduced technique. The design of the self-produced BIS plates maximizes the detection capacity of qualitative changes in cell culture and it is robust against physical effects and artifacts. The plates do not influence the viability and proliferation, however the results are robust, stable and reproducible regardless of when and where the experiments are carried out. In this study, physiological saline concentrations, two cancer and stem cell lines were utilized. All the results were statistically tested and confirmed. The findings of the assays show, that the introduced BIS technology is appropriate to be used in vitro experiments with high efficacy. The experimental results demonstrate high correlation values across the replicates, and the model parameters suggested that the characteristic differences among the various cell lines can be detected using appropriate hypothesis tests.

RGO-PANI composite Au microelectrodes for sensitive ECIS analysis of human gastric (MKN-1) cancer cells

Microelectrode-based cell chip studies for cellular responses often require improved adhesion and growth conditions for efficient cellular diagnosis and high throughput screening in drug discovery. Cell-chip studies are often performed on gold electrodes due to their biocompatibility, and stability, but the electrode-electrolyte interfacial capacitance is the main drawback to the overall sensitivity of the detection system. Thus, here, we developed reduced graphene oxide-polyaniline-modified gold microelectrodes for real-time impedance-based monitoring of human gastric adenocarcinoma cancer (MKN-1) cells. The impedance characterization on modified electrodes showed 28-fold enhanced conductivity than the bare electrodes, and the spectra were modeled with proper equivalent circuits to extrapolate the values of circuit elements. The impedance of both time-and frequency-dependent measurements of cell-covered modified electrodes with equivalent model circuits was analyzed to achieve cellular behavior, such as adhesion, spreading, proliferation, and influence of anti-cancer agents. The normalized impedance at 41.5 kHz (|Z|_{norm 41 kHz}) was selected to monitor the cell growth analysis, which was found linear with the proliferation of adherent cells along with the influence of the anticancer drug agent on the MKN-1 cells. The synergistic effects and biocompatible nature of PANI-RGO modifications improved the overall sensitivity for the cell-growth studies of MKN-1 cells.

Bioelectrical Impedance Spectroscopy for Monitoring Mammalian Cells and Tissues under Different Frequency Domains: A Review

Bioelectrical impedance analysis and bioelectrical impedance spectroscopy (BIA/BIS) of tissues reveal important information on molecular composition and physical structure that is useful in diagnostics and prognostics. The heterogeneity in structural elements of cells, tissues, organs, and the whole human body, the variability in molecular composition arising from the dynamics of biochemical reactions, and the contributions of inherently electroresponsive components, such as ions, proteins, and polarized membranes, have rendered bioimpedance challenging to interpret but also a powerful evaluation and monitoring technique in biomedicine. BIA/BIS has thus become the basis for a wide range of diagnostic and monitoring systems such as plethysmography and tomography. The use of BIA/BIS arises from (i) being a noninvasive and safe measurement modality, (ii) its ease of miniaturization, and (iii) multiple technological formats for its biomedical implementation. Considering the dependency of the absolute and relative values of impedance on frequency, and the uniqueness of the origins of the α-, β-, δ-, and γ-dispersions, this targeted review discusses biological events and underlying principles that are employed to analyze the impedance data based on the frequency range. The emergence of BIA/BIS in wearable devices and its relevance to the Internet of Medical Things (IoMT) are introduced and discussed.

A549 Cell-Covered Electrodes as a Sensing Element for Detection of Effects of Zn2+ Ions in a Solution

Electrochemical-based biosensors have the potential to be a fast, label-free, simple approach to detecting the effects of cytotoxic substances in liquid media. In the work presented here, a cell-based electrochemical biosensor was developed and evaluated to detect the cytotoxic effects of Zn²⁺ ions in a solution as a reference test chemical. A549 cells were attached to the surface of stainless-steel electrodes. After treatment with ZnCl₂, the morphological changes of the cells and, ultimately, their death and detachment from the electrode surface as cytotoxic effects were detected through changes in the electrical signal. Electrochemical cell-based impedance spectroscopy (ECIS) measurements were conducted with cytotoxicity tests and microscopic observation to investigate the behavior of the A549 cells. As expected, the Zn²⁺ ions caused changes in cell confluency and spreading, which were checked by light microscopy, while the cell morphology and attachment pattern were explored by scanning electron microscopy (SEM). The ECIS measurements confirmed the ability of the biosensor to detect the effects of Zn²⁺ ions on A549 cells attached to the low-cost stainless-steel surfaces and its potential for use as an inexpensive detector for a broad range of chemicals and nanomaterials in their cytotoxic concentrations.

Impact and trends in embedding field programmable gate arrays and microcontrollers in scientific instrumentation

Microcontrollers and field-programmable gate arrays have been largely leveraged in scientific instrumentation since decades. Recent advancements in the performance of these programmable digital devices, with hundreds of I/O pins, up to millions of logic cells, >10 Gb/s connectivity, and hundreds of MHz multiple clocks, have been accelerating this trend, extending the range of functions. The diversification of devices from very low-cost 8-bit microcontrollers up to 32-bit ARM-based ones and a system of chip combining programmable logic with processors make them ubiquitous in modern electronic systems, addressing diverse challenges from ultra-low power operation, with sub-µA quiescent current in sleep mode for portable and Internet of Things applications, to high-performance computing, such as in machine vision. In this Review, the main motivations (compactness, re-configurability, parallelization, low latency for sub-ns timing, and real-time control), the possible approaches of the adoption of embedded devices, and the achievable performances are discussed. Relevant examples of applications in opto-electronics, physics experiments, impedance, vibration, and temperature sensing from the recent literature are also reviewed. From this bird-eye view, key paradigms emerge, such as the blurring of boundaries between digital platforms and the pervasiveness of machine learning algorithms, significantly fostered by the possibility to be run in embedded devices for distributing intelligence in the environment.

Aluminium Oxide Thin-Film Based In Vitro Cell-Substrate Sensing Device for Monitoring Proliferation of Myoblast Cells

We demonstrate cell-substrate interaction on aluminium oxide thin-film in metal-insulator-metal structure followed by the change in dielectric characteristics of Al₂O₃ as a function of progression of cellular growth. The theoretical calculation of the fabricated biosensor reveals that the changes in the intrinsic elemental parameters are mainly attributed to the cell-induced behavioural changes.