Pesticides have been considered potential chemical mutagens and various agrochemical ingredients possess mutagenic properties. Biomonitoring provides a useful tool to estimate the genetic risk from exposure to a complex mixture of chemicals. In general genetic damage associated with pesticides occurs in human populations subject to high exposure levels due to ...

Leaf-level microscopical symptom structure and physiological responses were investigated in seedlings experimentally exposed to ozone (O3) in indoor chambers (150 ppb, 8 h d(-1)/7 weeks), and field trees of Manna ash (Fraxinus ornus) exposed to ambient O3 (max 93 ppb/one growing season). Ozone-induced leaf injury, including leaf reddening and stippling, ...

In this study, the potential of gold nanoparticles (20 nm) to deliver electrical stimulation to nerve cell cultures in vitro to induce nerve regeneration was evaluated. In order to use these biomaterials to deliver an electrical stimulus, we devised a novel method for the fabrication of a nanostructured 2D substrate ...

Electrochemical measurement of transmitter or hormone release from individual cells on microchips has applications both in basic science and drug screening. High-resolution measurement of quantal exocytosis requires the working electrode to be small (cell-sized) and located in immediate proximity to the cell. We examined the ability of candidate electrode materials ...

Endogenous direct-current electric fields (dcEFs) occur in vivo in the form of epithelial transcellular potentials or neuronal field potentials. A variety of cells respond to dcEFs by migrating directionally, and this is termed galvanotaxis. The mechanism by which dcEFs direct cell movement, however, is not yet understood, and the effects ...

Fr??hlich postulated coherent polar oscillations as a fundamental biophysical property of biological systems. Recently, Pelling et al. (2004, 2005) detected mechanical vibrations of yeast cell membrane with atomic force microscope (AFM) and analyzed by Fourier analysis in the frequency range 0.5-2 kHz with amplitudes of the order of 1 nm. ...

A cell-electrode interface noise model is developed which is dedicated to enable the co-simulation of the cell-electrode electrical characteristics, along with the electronics of novel CMOS-based MEA. The electrode noise is investigated for Pt and Pt black electrodes. It is shown that the electrode noise can be the dominant noise ...

We developed extremely small functionalized magnetic nanoparticles (MNPs) for use as an in vivo delivery system for pharmaceuticals and biomolecules. We functionalized the MNPs (d = 3 nm) by silanization of amino groups on the particles with (3-aminopropyl)triethoxysilane for subsequent cross-linking with pharmaceuticals and biomolecules. The MNPs were successfully introduced ...

Using a novel pressure membrane (PM) apparatus for the extraction of apoplastic fluid from field-grown grape (Vitis vinifera L.) berries, our hypothesis that significant apoplast solutes accumulate at the beginning of the ripening process (i.e. veraison), and that this accumulation might contribute to progressive berry softening due to a progressive ...

Removal of algal blooms in freshwater using magnetic polymer was studied by magnetic field. Results showed that magnetic polymer at optimal loadings (4 mg/Lferroferric oxide modified with 1.6 mg/Lchitosan) could remove over 99% algal cells; meanwhile, the removal efficiency of COD, total nitrogen and phosphorus was found to be 85.0%, ...

Cellular mechanics is known to play an important role in the cell homeostasis including proliferation, motility, and differentiation. Significant variation in the mechanical properties between different cell types suggests that control of the cell metabolism is feasible through manipulation of the cell mechanical parameters using external physical stimuli. We investigated ...

Focusing cells into a single stream is usually a necessary step prior to counting and separating them in microfluidic devices such as flow cytometers and cell sorters. This work presents a sheathless electrokinetic focusing of yeast cells in a planar serpentine microchannel using dc-biased ac electric fields. The concurrent pumping ...

In this paper, we describe the localized and selective electrical stimulation of single cells using a three-dimensional electrode array. The chip consisted of 84 nail-like electrodes with a stimulation surface of 0.8 um and interelectrode distances as small as 3 um. N2A cells were used to compare bipolar stimulation between ...

In vitro, morphogens such as transforming growth factor (TGF)-beta can up-and down-regulate cell growth at low and high concentrations respectively, i.e. they behave like hormetic agents. The hormetic morphogen theory of curvature proposes that in vivo tissue gradients of such morphogens secreted by source cells determine the fate of cells ...

This work investigates the effect of ultrasound exposure parameters on the sonoporation of KHT-C cells in suspension by perflutren microbubbles. Variations in insonating acoustic pressure (0.05 to 3.5 MPa), pulse frequency (0.5 to 5.0 MHz), pulse repetition frequency (10 to 3000 Hz), pulse duration (4 to 32 micros) and insonation ...

The use of cell-penetrating peptides as transduction vectors is a promising approach to deliver peptides and proteins into cells. However, the uptake and bioavailability of trans-activating transcriptor (TAT)-conjugated molecules vary depending on the cell type and the cargo. This study aimed to determine whether a low-voltage electrical pulse can enhance ...

Drought is the single most limiting factor in crop production. This study was conducted to investigate if a cell viability assay could serve as an effective, efficient screen to determine post-anthesis drought tolerance in sorghum (Sorghum bicolor [L.] Moench) and maize (Zea mays [L]). The assay measured decline in chlorophyll ...

This paper presents hydrodynamic trapping of bioparticles in a microfluidic device. An in-plane oscillatory microplate, driven via Lorentz law, generates two counter-rotating microvortices, trapping the bioparticles within the confines of the microvortices. The force required to trap bioparticles is quantified by tuning the background flow and the microplate's excitation voltage. ...

AIM: Efforts are underway to establish a preparation method for the phycoerythrin subunit (PE-sub) liposome, and enhance the cellular uptake and photodynamic therapy (PDT) effect on cancer cells. METHODS: A film dispersion method was used to prepare the PE-sub liposome, an orthogonal analysis was conducted to optimize the PE-sub liposome ...

Vertically aligned Mg-doped GaN nanorods have been epitaxially grown on n-type Si substrate to form a heterostructure for fabricating p-n heterojunction photovoltaic cells. The p-type GaN nanorod/n-Si heterojunction cell shows a well-defined rectifying behavior with a rectification ratio larger than 10(4) in dark. The cell has a high short-circuit photocurrent ...

The authors present the use of electric-field constriction created by a microfabricated structure to realise high-yield electrofusion of biological cells. The method uses an orifice on an electrically insulating wall (orifice plate) whose diameter is as small as that of the cells. Owing to the field constriction created by the ...

Two lipophilic methotrexate analogues have been synthesized and evaluated for cytotoxicity against KATO III and HT-29 human colon cancer cells. Both analogues contained a C16-alkyl chain attached to the gamma-carboxylic acid and one of the analogues had an additional benzyl group attached to the alpha-carboxylic acid. The cytotoxicity of the ...

Magnetic selection allows high-throughput sorting of target cells based on surface markers, and it is extensively used in biotechnology for a wide range of applications from in vitro diagnostics to cell-based therapies. However, existing methods can only perform separation based on a single parameter (i.e., the presence or absence of ...

PURPOSE: The objective of this research is to investigate dynamic responses of the piezoelectric Braille cell when it is subjected to both electrical signal and touching force. METHOD: Physical behavior of the piezoelectric actuator inside the piezoelectric Braille cell is analyzed. The mathematical model of the piezoelectric Braille system is ...

Defibrillator-type shocks may cause electric and contractile dysfunction. In this study, we determined the relationship between probability of lethal injury and electric field intensity (E in isolated rat ventricular myocytes, with emphasis on field orientation and stimulus waveform. This relationship was sigmoidal with irreversible injury for E > 50 V/cm ...

Neuro-electronic hybrid devices are cell based biosensors using neuronal cells. The electrical activity of these cells allows integration with electrical read-out sensors and stimulation electrodes. The electrical coupling between the neurons and the sensor is critical element in order to obtain high signal to noise ratio recordings and controlled stimulation.<br/> ...

We report on the electrical impedance spectroscopy characterization of OVCA429 ovarian cancer cells. A commercially available eight-well cell culture impedance array (ECIS-8W1E), commonly used in electrical cell-substrate impedance sensing (ECIS), was used for OVCA429 characterization. Impedances of ECIS-8W1E array were recorded with cell culture medium (without cells) and with OVCA429 ...

This paper presents hydrodynamic trapping of bioparticles in a microfluidic device. An in-plane oscillatory microplate, driven via Lorentz law, generates two counter-rotating microvortices, trapping the bioparticles within the confines of the microvortices. The force required to trap bioparticles is quantified by tuning the background flow and the microplate's excitation voltage. ...

Vertically aligned Mg-doped GaN nanorods have been epitaxially grown on n-type Si substrate to form a heterostructure for fabricating p-n heterojunction photovoltaic cells. The p-type GaN nanorod/n-Si heterojunction cell shows a well-defined rectifying behavior with a rectification ratio larger than 10 (4) in dark. The cell has a high short-circuit ...

An efficient numerical method based on the Dirichlet-to-Neumann (DtN) maps of the unit cells is developed for accurate simulations of two-dimensional photonic crystal (PhC) devices in the frequency domain. The DtN map of a unit cell is an operator that maps the wave field on the boundary of the cell ...

This paper describes the fabrication of microarrays that enable the parallel electroporation of small interfering RNAs (siRNAs) into mammalian cells. To optimize the conditions of microarray preparation and electric pulsing, a self-assembled monolayer was formed on a gold electrode, and a cationic polymer was adsorbed by the entire surface of ...

Pesticides used to control unwanted insects are potentially toxic to humans. In assessing the risk involved in exposure to pesticides or complex chemical mixtures, an in vitro cell-based test can provide useful information regarding danger to human health. Cell differentiation is a biological process of fundamental importance in developing and ...

The ability to rapidly and efficiently isolate specific viruses, bacteria, or mammalian cells from complex mixtures lies at the heart of biomedical applications ranging from in vitro diagnostics to cell transplantation therapies. Unfortunately, many current selection methods for cell separation, such as magnetic activated cell sorting (MACS), only allow the ...

Microchip technology has matured over the years into an important field in which novel technologies are being constantly invented, and down-sizing and incorporation of already existing methodologies into the microscale is increasing assay performance and bearing the promise of future total integration for simple, widespread use. One rapidly growing sub-discipline ...

Impedance spectroscopy is a sensitive technique to characterize the chemical and physical properties of solid, liquid, and gas phase materials. In recent years this technique has gained widespread use in developing biosensors for monitoring the catalyzed reaction of enzymes; the bio-molecular recognition events of specific proteins, nucleic acids, whole cells, ...

We document the activation of transient polar arcs emanating from the cusp within a 15 min long intermediate phase during the transition from a standard two-cell convection pattern, representative of a strongly southward interplanetary magnetic field (IMF), to a "reverse" two-cell pattern, representative of strongly northward IMF conditions. During the ...

Owing to the small quantities of analytes and small volumes involved in single-cell analysis techniques, manipulation strategies must be chosen carefully. The lysis of single cells for downstream chemical analysis in capillaries and lab-on-a-chip devices can be achieved by optical, acoustic, mechanical, electrical or chemical means, each having their respective ...

Lab-on-a-chip systems offer a versatile environment in which low numbers of cells and molecules can be manipulated, captured, detected and analysed. We describe here a microfluidic device that allows the isolation, electroporation and lysis of single cells. A431 human epithelial carcinoma cells, expressing a green fluorescent protein-labelled actin, were trapped ...

For this special issue of J. R. Soc. Interface we present an overview of the driving forces behind technological advances in the field of single-cell analysis. These range from increasing our understanding of cellular heterogeneity through to the study of rare cells, areas of research that cannot be tackled effectively ...

A miniaturized microfluidic device was developed to facilitate electromanipulation of bacterial respiratory pathogens. The device comprises a microchip with circular aluminum electrodes patterned on glass, which is housed in a microfluidic system fabricated utilizing polydimethylsiloxane. The device provides sample preparation capability by exploiting positive dielectrophoresis (DEP) in conjunction with pulsed ...

Cochlear implants (CIs) can restore hearing in deaf patients by electrical stimulation of the auditory nerve. To optimize the electrical stimulation, the number of independent channels must be increased by reduction of connective tissue growth on the electrode surface and selective neuronal cell contact. The femtosecond laser microstructuring of the ...

Pulsed power for biological investigations newly developed at USC include a fast diode-based systems designed to drive cell suspensions in a microscope slide electrode microchamber for observations of living cells during pulse exposure with pulse durations from 3 ns to 30 ns and electric fields from 1 MV/m to 10 ...

Single-cell electroporation (SCEP) is a recently developing powerful technique for cell analysis and cell manipulation. In the first chapter of this thesis, a review about the theories and techniques is fulfilled, including a detailed description of the factors affecting SCEP, and a discussion about how to optimize SCEP for high ...

In this review we compile and discuss the published plethora of cell biological effects which are ascribed to electric fields (EF), magnetic fields (MF) and electromagnetic fields (EMF). In recent years, a change in paradigm took place concerning the endogenously produced static EF of cells and tissues. Here, modern molecular ...

We have investigated interaction of alkyphospholipid (APL) liposomes consisting of 1,1-dimethylpiperidin-1-ium-4-yl) octadecyl phosphate (OPP) and different concentrations of cholesterol (CH) with human MT-3 breast-cancer cells using electron paramagnetic resonance method (EPR) with advanced characterization of EPR spectra of spin labeled liposome membranes. After incubation of OPP liposomes with MT-3 cells, ...

We have developed novel cocktail liposomes bearing doxorubicin in their hydrophilic cores, and amiodarone, a potent multidrug resistance inhibitor, in their lipid bilayers. The efficacy of these liposomes was studied in DU145 human prostate carcinoma cells. Intracellular calcein retention, which is inversely proportional to multidrug resistance activity, significantly increased following ...

This work tackles the development of numerical methods in order to study the influence of a nanosecond electrical pulse on the phenomena arising in a biological cell. Formulations employed are presented and applied to the observation of the sensitivity of an eukaryote cell to the orientation of the electric field.

On the 22 December 2002 the interplanetary magnetic field (IMF) was directed northwards for more than 12h. The Northern and Southern Hemisphere SuperDARN radars were used to study global high-latitude convection during this interval, complemented by data from the ACE and DMSP F13 spacecraft. The relative magnitudes of the IMF ...

Cells undergoing apoptosis lose lipid asymmetry that is often manifested by the exposure of phosphatidylserine (PS) to the outer surface of the cell membrane. Macrophages and other cell types recognize externalized PS to signal phagocytosis, thereby eliciting a non-inflammatory response. PS exposure is obligatory in the recognition and clearance of ...

PURPOSE: The aim of the study was to analyze the influence of rotating magnetic fields (RMF) on the expression and intranuclear distribution of nucleolin, protein involved in ribosome biosynthesis, in HL-60 (acute promyelocytic leukemia) and K-562 (chronic myelogenous leukemia) established human cell lines. MATERIALS AND METHODS: Cells were exposed to ...