Optimization, fabrication, and characterization of four electrode-based sensors for blood impedance measurement.

In this work, an optimized, non-invasive four electrode-based impedimetric sensors have been designed, fabricated, and characterized for measuring the impedance of a biological cell. The impedimetric sensors having four mono-polar electrodes were fabricated utilizing the photolithography technique with gold as the electrode material. Furthermore, the impedance of the electrolyte/electrode interface was simulated by optimizing different parameters, including applied voltage, PBS thickness, and diameter, using COMSOL Multiphysics software for a frequency range of 100 Hz to 1 MHz. Next, the impedance of the fabricated device was measured experimentally using the electrochemical impedance spectroscopy (EIS) technique. Then, the COMSOL data was equated with the impedance obtained from the fabricated devices to realize the feasibility and error percentage (RSE < 5%) of the sensor. The equivalent circuit model for the measured impedance data of PBS was obtained utilizing the ZsimpWin software. Besides, the mathematical relations between the impedance, phase angle and the area of the electrode were interpreted for the fabricated impedimetric sensors. Later on, a real blood sample was also characterized to demonstrate the feasibility and the validity of the proposed technique and the fabricated devices in cell diagnosis.

Four electrode-based impedimetric biosensors for evaluating cytotoxicity of tamoxifen on cervical cancer cells.

In the current study, novel four electrode-based impedimetric biosensors have been fabricated using photolithography techniques and utilized to evaluate the cytotoxicity of tamoxifen on cervical cancer cell lines. The cell impedance was measured employing the electric cell-substrate impedance sensing (ECIS) method over the frequency range of 100 Hz to 1 MHz. The results obtained from impedimetric biosensors indicate that tamoxifen caused a significant reduction in the number of HeLa cells on the electrode surfaces in a dose-dependent manner. Next, the impedance values recorded by the fabricated biosensors have been compared with the results obtained from the different conventional techniques such as 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT), live-dead cell assay, and flow cytometric analysis to estimate the cytotoxicity of tamoxifen. The impedimetric cytotoxicity of tamoxifen over the growth and proliferation of HeLa cells correlates well with the traditional methods. In addition, the IC50 values obtained from impedimetric data and MTT assay are comparable, signifying that the ECIS technique can be an alternative method to assess the cytotoxicity of different novel drugs. The working principle of the biosensor has been examined by scanning electron microscopy, indicating the detachment of cells from gold surfaces in a dose-dependent manner, signifying the decrease in impedance at higher drug doses.

Differential neural cell adhesion and neurite outgrowth on carbon nanotube and graphene reinforced polymeric scaffolds.

Carbon nanomaterials, such as graphene nanoplatelets (GNPs) and multiwalled carbon nanotubes (MWCNTs) are potential candidates in a large number of biomedical applications. The present study investigates the effect of the difference in morphology of these materials on neural cell regeneration on a biodegradable scaffold. Electrical conductivities of all the hybrid scaffolds are found to be in between that of MWCNT/chitosan scaffold (highest-conductivity) and GNP/chitosan scaffold (lowest-conductivity). While, hybrid scaffolds show improvement in elastic modulus and ultimate tensile strength over MWCNT/chitosan and GNP/chitosan scaffolds. The protein adsorption isotherms of bovine serum albumin (BSA) show greater equilibrium constant (Keq) on GNP/chitosan composites as compared to MWCNT/chitosan composites, proving more potential for cell adhesion in the former. Interactions of HT-22 hippocampal neurons with MWCNT/chitosan, GNP/chitosan and various MWCNT/GNP hybrid chitosan matrices prove cytocompatibility. The neurons acquire elongated geometry on the MWCNT/chitosan scaffold, while GNP reinforcement drives the neurons to spread cellular processes radially.