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Immunology
Published in Paul Pumpens, Single-Stranded RNA Phages, 2020
Electrochemical biosensors featuring oriented antibody immobilization via electrografted and self-assembled hydrazide chemistry were applied for the MS2 detection by Prieto-Simón et al. (2014). This study presented two new functionalization strategies that preserved proper folding and binding potential of antibodies by forcing their oriented immobilization. Both strategies were based on the formation of hydrazone bonds between aldehyde groups on the Fc moieties of periodate-oxidized antibodies and hydrazide groups on functionalized gold electrodes. Those hydrazide groups were introduced by electrografting of diazonium salts or by self-assembly of mono- and dithiolated hydrazide linkers, resulting in films with tailored functional groups, and thus antibody distribution and spacing. The MS2 detection was performed through either a direct assay using electrochemical impedance spectroscopy or through a sandwich assay using differential pulse voltammetry. The best results of 15 pfu/mL were achieved for immunosensors based on mixed monolayers of hydrazide and hydroxyl diothiolated linkers (Prieto-Simón et al. 2014).
Regeneration: Nanomaterials for Tissue Regeneration
Published in Harry F. Tibbals, Medical Nanotechnology and Nanomedicine, 2017
In a related series of experiments, the Texas Scottish Rite group tested elec-trodeposited, photolithographic, and micromachined gold microelectrodes for nerve cell stimulation [45]. The gold microprobe interface was modified by the addition of conductive polymers and carbon nanotubes. It was observed that the addition of carbon nanotubes favors the formation of nodules and increases the surface roughness. Also, electrochemical impedance spectroscopy revealed that conductive polymer composites lower the impedance of gold microelectrodes by three orders of magnitude. The carbon nanotube/polymer composite-coated electrodes maintain intimate contact with axons, enabling high-quality nerve spike signals and electrical stimulation of neurons.
Energy Medicine: Focus on Nonthermal Electromagnetic Therapies
Published in Len Wisneski, The Scientific Basis of Integrative Health, 2017
Len Wisneski, Bernard O. Williams
In recent years, the increase in instrument power and sophistication has permitted the visualization of body energy beyond the boundary of the skin. Superconducting quantum interference devices, or SQUID, routinely detect magnetic signals from the brain, heart, and other endogenous current sources. Chapter 6 presents the finding that SQUID measurements have demonstrated energetic effects emanating from the hands of QiGong Masters. This and similar technologies have focused on particular subsystems of the body; however, an application of multi-instrument computerized tomography potentially might be capable of synthesizing subsystem measurements into a representation of Liboff's electrogenomic composite field vector. In a review of progress in magnetoencephalography (MEG), an imaging technique that measures magnetic fields produced by electrical activity in the brain, Ioannides, a leader in the field of magnetic field imaging, concluded that: “a noninvasive and truly functional imaging capability of the brain and body is within reach” (Ioannides, 1994). Although the precise way to achieve this integration is unclear, Ioannides suggests that combining information from regular and functional magnetic resonance imaging, positron emission tomography, MEG, and EEG would surely contribute to studies of the mind. Similarly, James Oschman proposes that recent developments in electrical impedance tomography assessments of the electronic properties of living matter may soon be capable of visualizing human energy (IEEE, 2002, Oschman, 2004). As mentioned, later in this chapter, two additional innovations in bioelectrical impedance assessments, the SEQEX and EIS systems, will be reviewed.
Nucleic acid-based electrochemical biosensors for rapid clinical diagnosis: advances, challenges, and opportunities
Published in Critical Reviews in Clinical Laboratory Sciences, 2022
Abu Hashem, M. A. Motalib Hossain, Ab Rahman Marlinda, Mohammad Al Mamun, Suresh Sagadevan, Zohreh Shahnavaz, Khanom Simarani, Mohd Rafie Johan
The impedimetric biosensor, which is fabricated by immobilizing the NA probe onto the transducer surface, uses impedance as the transduction principle. Impedimetric biosensors measure the variation in charge capacitance and conductance of the electrode surface as determined by the variation in the activity of the electrons or ions generated during the conjugation of receptors and target analytes [71]. Generally, an electrochemical impedance spectroscopy (EIS) technique is used to measure the changes in impedance [72] generated due to hybridization or coupling of analytes with designed probes or aptamers. EIS is a sensitive indicator for diverse chemical and physical properties [73–75]. It may also be designed without the need for indicator molecules, that is, for label-free detection. This non-destructive technique could be used as a tool for investigating biorecognition events at the electrode surface [76]. However, it is time-consuming compared with amperometry or potentiometry, and may not be appropriate for POC applications. An example of an impedimetric biosensor is shown in Figure 5 [77].
A simple immunosensor for thyroid stimulating hormone
Published in Artificial Cells, Nanomedicine, and Biotechnology, 2021
Hakki Mevlut Ozcan, Umut Deniz Aydin
In recent years, Electrochemical Impedance Spectroscopy (EIS) based impedimetric biosensors are interesting because of their short determination times, high sensitivity, low detection limits and simplicity. Impedimetric immunosensors have been developed for hormones such as oestrogen, parathyroid hormone, human growth hormone, insulin and TSH [40–44]. The concentration of the target analyte can easily be determined with EIS by measuring the change in the charge transfer resistance that occurs when the antigen was bounded to the antibody immobilized on the working electrode surface. Nyquist curves obtained from EIS spectra are typically composed of two sections, linear and semicircular, and the diameter of the semicircle is used to calculate the charge transfer resistance on the surface of the working electrode [45].
Continuous flow system for biofilm formation using controlled concentrations of Pseudomonas putida from chicken carcass and coupled to electrochemical impedance detection
Published in Biofouling, 2020
Daoyuan Yang, José I. Reyes-De-Corcuera
The electrochemical impedance spectroscopy (EIS) was performed by a Reference 600 potentiostat (Gamry, Warminster, PA). Two SS tubes identical to those used to recover biofilm cells for TPC served as the working and counter electrodes, which were assumed to have the same level of biofilm formation as the other tubing pieces tested using TPC. The ‘LowProfile’ 60-mm long Ag|AgCl glass electrode filled with 3.5 M KCl (Pine Research Instrumentation, Durham, NC) was used as the reference electrode. The three electrodes were inserted into a custom-made ‘T’ connector to be the electrochemical cell (Figure 1D). The SS tubes were placed to ensure their distance to the reference electrode the same every time. The reference electrode was precisely inserted with its frit end flushed with the inner surface of the ‘T’ connector. The use of SS tubes as working and counter electrodes was for the simplicity by introducing only the reference electrode to potentially apply this study to pipelines in industry to develop an in-line biofilm detector.