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Diagnosis: Nanosensors in Diagnosis and Medical Monitoring
Published in Harry F. Tibbals, Medical Nanotechnology and Nanomedicine, 2017
Cells and polarizable particles can be moved and manipulated by the application of electromagnetic fields, either static (electrophoresis) or dynamic (dielectrophoresis) [216-218]. Electrophoresis is a relatively straightforward technique compared to generating and applying more complex variable fields needed for dielectrophoresis, whose development has only come about with the availability of sophisticated digital electronics. The forces on cells produced by dielectrophoresis depend on the polarizability as well as size; dynamic electromagnetic fields focused by electrodes surrounding a fluid can be used to separate different types of cells, including normal and cancer cells [219-221]. Nonlinear effects produced by high localized field strengths and spatial variation of the field densities can produce eddys, traps, and nonlinear effects [222,223]. Electromagnetic fields can be used for electroosmotic mixing in microfluidics. Dielectrophoresis and electroosmotic mixing can be applied by means of noncontact electrodes, eliminating contamination and electrochemical reactions at the electrode surface, and facilitating reusable designs [224,225]. Electrodes surrounding or incorporating microfluidic channels and chambers can be made by coatings of biocompatible conductive materials, machined out of metals, or printed on circuit boards [226-228]. Various related means of forming traps with electromagnetic fields have been developed and applied to microflu-idic analysis [228,229].
The Kinetics of Artificially Induced Membrane Fusion
Published in Sek Wen Hui, Freeze-Fracture Studies of Membranes, 1989
The kinetics of electrofusion of erythrocyte membranes was determined by a fluorescence contents mixing assays. A special front-face fluorometer curvette with built-in electrodes was constructed for this purpose.22 Human erythrocyte ghost membranes were loaded with Tb or DPA as described by Hoestra et al.,23 and placed between electrodes in the curvette. The loaded cells were prealigned by dielectrophoresis in a 1-MHz electric field of the strength 500 V/cm. A short (15 to 50 μs) square pulse at 2.5 to 5.0 kV/cm was applied to induce fusion between aligned cells. Fusion was measured as the increase of fluorescence upon the mixing of Tb and DPA, whereas leakage was measured as the decrease of fluorescence from vesicles loaded with mixed Tb + DPA and suspended in a EDTA-containing medium. Fluorescence intensity increased immediately after the pulse application. Within 2 s, the fluorescence reached its peak value, then declined slowly over a period of tens of seconds.22 The maximum rate of fusion occurs within the first second and reaches a percentage rate of 50%/s.
Low frequency vortex magnetic field reduces amyloid β aggregation, increase cell viability and protect from amyloid β toxicity
Published in Electromagnetic Biology and Medicine, 2021
Alejandro Maldonado-Moreles, Teodoro Cordova-Fraga, Herlinda Bonilla-Jaime, Perla Y. Lopez-Camacho, Gustavo Basurto-Islas
This is the first report that demonstrates VMF stimulation blocks or delays Aβ peptide fibril formation. Likewise, VMF prevented Aβ aggregates toxicity and increased cell viability in neuroblastoma cell line. A significant decrease in Aβ aggregates was observed by Th-T assay and WB after exposure to VMF, which can be explained assuming that MF inhibits Aβ-Aβ binding at least during the exposed time, arresting the sequential process of Aβ aggregation in the nucleation phase, identified by low molecular weight oligomers showed by WB. The inhibition of Aβ fibril formation by VMF stimulation was assessed indirectly by cell viability assay in SH-SY5Y cell culture. As expected, VMF bear the antiaggregatory effect on resuspended Aβ in culture media, since it is known that water induces a minimal effect on MF. Nevertheless, the molecular mechanism involved in cell proliferation by VMF stimulation remains obscure. It is known that uniform EMF promotes human cell proliferation by decreasing intracellular reactive oxygen species levels and increasing expression of cell cycle markers, so it is possible that VMF induces a similar molecular mechanism. Intracellular dielectrophoresis occurs when EMF stimulate cells, moving polar molecules toward higher field intensities and thus generating different effects in reactive oxygen species or inducing the activation of proliferation signaling pathways. Recently our research group exposed SH-SY5Y cells to VMF and identify by proteomics more than 100 differential protein (unpublished data), the analysis leads us to understand the biological alteration induced by VMF, not only to evaluate the possibility of harmful effects at the metabolic level of exposure to VMF but also to investigate possible therapeutic applications.
The potential of monitoring treatment response in non-small cell lung cancer using circulating tumour cells
Published in Expert Review of Molecular Diagnostics, 2019
Marianna Gallo, Antonella De Luca, Daniela Frezzetti, Valeria Passaro, Monica R. Maiello, Nicola Normanno
Devices based on dielectrophoresis (DEP) enable to sort and recover pure single cells avoiding contaminations from leucocytes. The DEPArray technology allows single CTC isolation of cells trapped in electric cages, subjected to an electric field and individually moved into a holding chamber for the subsequent detection and recovery [35]. The DEPArray System has been used to isolate single viable cells with a high grade of purity from different tumor types [36–38]. However, this technology requires previous capture and enrichment of CTCs with other methods.
The prognostic role of circulating tumor cells in colorectal cancer
Published in Expert Review of Anticancer Therapy, 2019
Lahiri Kanth Nanduri, Barbara Hissa, Jürgen Weitz, Sebastian Schölch, Ulrich Bork
Dielectrophoresis (DEP), for example, is another CTC isolation method that relies on bioelectrical properties to sort the cells. Using this procedure, CTCs are trapped inside di-electrophoretic cages. DEP, commercially available as DEPArray, allows isolation of single cells that can be evaluated both genomically and transcriptomically [81,82]. This method is also using biomarker targeting. For a list of methods used for CTC isolation, please see Table 1.