Intense Pulsed Electric Fields Denature Urease Proteins

AbstractThis paper describes the effects of nanosecond pulsed electric fields (nsPEFs) on the structure and enzyme activity of three kinds of proteins. Intense (up to 300 kV/cm), 5-ns-long electrical pulses were applied to solutions of lysozyme (14 kDa, monomer), albumin (67 kDa, monomer), and urease (480 kDa, hexamer). We analyzed the tertiary and quaternary structures of these proteins as well as their enzyme activity. The results indicated the deformation of both the quaternary and tertiary structures of urease upon exposure to an electric field of 250 kV/cm or more, whereas no structural changes were observed in lysozyme or albumin, even at 300 kV/cm. The enzyme activity of urease also decreased at field strengths of 250 kV/cm or more. Our experiments demonstrated that intense nsPEFs physically affect the conformation and function of some kinds of proteins. Such intense electric fields often occur on cell membranes when these are exposed to a moderate pulsed electric field.

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Simulation of Carbon Nanotube-Based Enhancement of Cellular Electroporation under Nanosecond Pulsed Electric Fields

BioMed Research International ◽

10.1155/2019/9654583 ◽

2019 ◽

Vol 2019 ◽

pp. 1-10

Author(s):

Yan Mi ◽

Quan Liu ◽

Pan Li ◽

Jin Xu

Keyword(s):

Field Strength ◽

Electric Field ◽

Electric Field Strength ◽

Tumor Cells ◽

Electric Fields ◽

Pulsed Electric Fields ◽

Local Electric Field ◽

Killing Effect ◽

Nanosecond Pulsed Electric Fields ◽

Local Electric Field Strength

Carbon nanotubes (CNTs) with large aspect ratios and excellent electrical properties can enhance the killing effect of nanosecond pulsed electric fields (nsPEFs) on tumor cells, which can improve the electrical safety of nsPEF during tumor treatment. To study the mechanism of the CNT-enhanced killing effect of a nsPEF on tumor cells, a spherical, single-cell, five-layer dielectric model containing randomly distributed CNTs was established using COMSOL and MATLAB, and then, the effects of the addition of CNTs on the electric field and the electroporation effect on the inner and outer membranes were analyzed. The results showed that CNTs can enhance the local electric field strength due to a lightning rod effect, and the closer the CNT tip was to the cell, the greater the electric field strength was around the cell. This increase in the local electric field strength near the cells enhanced the electroporation effects, including pore density, pore area, and pore flux. The simulation results presented in this paper provide theoretical guidance for subsequent development of nsPEF combined with CNTs for use in both cell and tissue experiments.

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Printed Flexible Microelectrode for Application of Nanosecond Pulsed Electric Fields on Cells

Materials ◽

10.3390/ma12172713 ◽

2019 ◽

Vol 12 (17) ◽

pp. 2713 ◽

Cited By ~ 1

Author(s):

Martin Schubert ◽

Jens Rasche ◽

Mika-Matti Laurila ◽

Tiina Vuorinen ◽

Matti Mäntysalo ◽

...

Keyword(s):

Electric Fields ◽

Low Cost ◽

Human Fibroblasts ◽

Tumor Therapy ◽

Pulsed Electric Fields ◽

Electrical Circuit ◽

Electrical Pulses ◽

Nanosecond Pulsed Electric Fields ◽

Field Strengths

Medical treatment is increasingly benefiting from biomedical microsystems, especially the trending telemedical application. A promising modality for tumor therapy showed the application of nanosecond pulsed electric fields (nsPEF) on cells to achieve nanoporation, cell death, and other cell reactions. A key technology for this method is the generation of pulsed fields in the nanosecond range with high-field strengths in the range of several kilovolts per centimeter. For further biomedical applications, state-of-the-art setups need to decrease in size and improve their capability of integration into microsystems. Due to demanding electronic requirements, i.e., using high voltages and fast pulses, miniaturization and low-cost fabrication of the electrode is first considered. This paper proposes a proof-of-concept for a miniaturized printed flexible electrode that can apply nsPEF on adherent fibroblast cells. The interdigital gold electrode was printed on polyimide with line-width of about 10 µm using an electrohydrodynamic inkjet printer. Furthermore, an electrical circuit was developed to generate both electrical pulses in the nano-second range and voltages up to 180 V. The electrode was integrated into an experimental setup for in-vitro application to human fibroblasts. Field strengths up to 100 kV/cm with 45 ns pulse duration were applied, depending on the degree of cell confluence. The cells show contraction, detachment from the electrode, and lethal reactions after the nsPEF treatment. Furthermore, this printed miniaturized electrode was found to be suitable for subsequent microsystem integration and further cell experiments to optimize pulse parameters for control of cell reaction and behavior.

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Towards Solid Tumor Treatment by Nanosecond Pulsed Electric Fields

Technology in Cancer Research & Treatment ◽

10.1177/153303460900800406 ◽

2009 ◽

Vol 8 (4) ◽

pp. 289-306 ◽

Cited By ~ 38

Author(s):

Axel T. Esser ◽

Kyle C. Smith ◽

T. R. Gowrishankar ◽

James C. Weaver

Keyword(s):

Cell Death ◽

Electric Field ◽

Spatial Scale ◽

Electric Fields ◽

Solid Tumor ◽

Irreversible Electroporation ◽

Pulsed Electric Fields ◽

Underlying Mechanism ◽

Tumor Ablation ◽

Nanosecond Pulsed Electric Fields

Local and drug-free solid tumor ablation by large nanosecond pulsed electric fields leads to supra-electroporation of all cellular membranes and has been observed to trigger nonthermal cell death by apoptosis. To establish pore-based effects as the underlying mechanism inducing apoptosis, we use a multicellular system model (spatial scale 100 μm) that has irregularly shaped liver cells and a multiscale liver tissue model (spatial scale 200 mm). Pore histograms for the multicellular model demonstrate the presence of only nanometer-sized pores due to nanosecond electric field pulses. The number of pores in the plasma membrane is such that the average tissue conductance during nanosecond electric field pulses is even higher than for longer irreversible electroporation pulses. It is shown, however, that these nanometer-sized pores, although numerous, only significantly change the permeability of the cellular membranes to small ions, but not to larger molecules. Tumor ablation by nanosecond pulsed electric fields causes small to moderate temperature increases. Thus, the underlying mechanism(s) that trigger cell death by apoptosis must be non-thermal electrical interactions, presumably leading to different ionic and molecular transport than for much longer irreversible electroporation pulses.

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Tuning the Electric Field Response of MOFs by Rotatable Dipolar Linkers

10.26434/chemrxiv.8153198.v1 ◽

2019 ◽

Author(s):

Johannes P. Dürholt ◽

Babak Farhadi Jahromi ◽

Rochus Schmid

Keyword(s):

Electric Field ◽

Electric Fields ◽

Structural Changes ◽

Dielectric Behavior ◽

Two Dimensions ◽

Dielectric Constants ◽

Electric Response ◽

Dipole Strength ◽

Metal Organic ◽

Dynamics Simulations

Recently the possibility of using electric fields as a further stimulus to trigger structural changes in metal-organic frameworks (MOFs) has been investigated. In general, rotatable groups or other types of mechanical motion can be driven by electric fields. In this study we demonstrate how the electric response of MOFs can be tuned by adding rotatable dipolar linkers, generating a material that exhibits paralectric behavior in two dimensions and dielectric behavior in one dimension. The suitability of four different methods to compute the relative permittivity κ by means of molecular dynamics simulations was validated. The dependency of the permittivity on temperature T and dipole strength μ was determined. It was found that the herein investigated systems exhibit a high degree of tunability and substantially larger dielectric constants as expected for MOFs in general. The temperature dependency of κ obeys the Curie-Weiss law. In addition, the influence of dipolar linkers on the electric field induced breathing behavior was investigated. With increasing dipole moment, lower field strength are required to trigger the contraction. These investigations set the stage for an application of such systems as dielectric sensors, order-disorder ferroelectrics or any scenario where movable dipolar fragments respond to external electric fields.

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Gene expression analysis of apoptosis pathway in HeLa S3 cells subjected to nanosecond pulsed electric fields

2011 IEEE Pulsed Power Conference ◽

10.1109/ppc.2011.6191588 ◽

2011 ◽

Author(s):

M. Yano ◽

K. Abe ◽

S. Katsuki ◽

H. Akiyama

Keyword(s):

Gene Expression ◽

Electric Fields ◽

Expression Analysis ◽

Gene Expression Analysis ◽

Pulsed Electric Fields ◽

Apoptosis Pathway ◽

Hela S3 ◽

Nanosecond Pulsed Electric Fields ◽

Hela S3 Cells

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Integrating flexible electronics for pulsed electric field delivery in a vascularized 3D glioblastoma model

npj Flexible Electronics ◽

10.1038/s41528-021-00115-x ◽

2021 ◽

Vol 5 (1) ◽

Author(s):

Marie C. Lefevre ◽

Gerwin Dijk ◽

Attila Kaszas ◽

Martin Baca ◽

David Moreau ◽

...

Keyword(s):

Electric Field ◽

Electric Fields ◽

Flexible Electronics ◽

Soft Tissues ◽

Multiphoton Microscopy ◽

Membrane Integrity ◽

Tumor Model ◽

Pulsed Electric Fields ◽

In Ovo ◽

Cell Membrane Integrity

AbstractGlioblastoma is a highly aggressive brain tumor, very invasive and thus difficult to eradicate with standard oncology therapies. Bioelectric treatments based on pulsed electric fields have proven to be a successful method to treat cancerous tissues. However, they rely on stiff electrodes, which cause acute and chronic injuries, especially in soft tissues like the brain. Here we demonstrate the feasibility of delivering pulsed electric fields with flexible electronics using an in ovo vascularized tumor model. We show with fluorescence widefield and multiphoton microscopy that pulsed electric fields induce vasoconstriction of blood vessels and evoke calcium signals in vascularized glioblastoma spheroids stably expressing a genetically encoded fluorescence reporter. Simulations of the electric field delivery are compared with the measured influence of electric field effects on cell membrane integrity in exposed tumor cells. Our results confirm the feasibility of flexible electronics as a means of delivering intense pulsed electric fields to tumors in an intravital 3D vascularized model of human glioblastoma.

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