Intense pulsed electric fields (PEF) are a novel modality for the efficient and targeted ablation of tumors by electroporation. The major adverse side effects of PEF therapies are strong involuntary muscle contractions and pain. Nanosecond-range PEF (nsPEF) are less efficient at neurostimulation and can be employed to minimize such side effects. We quantified the impact of the electrode configuration, PEF strength (up to 20 kV/cm), repetition rate (up to 3 MHz), bi- and triphasic pulse shapes, and pulse duration (down to 10 ns) on eliciting compound action potentials (CAPs) in nerve fibers. The excitation thresholds for single unipolar but not bipolar stimuli followed the classic strength–duration dependence. The addition of the opposite polarity phase for nsPEF increased the excitation threshold, with symmetrical bipolar nsPEF being the least efficient. Stimulation by nsPEF bursts decreased the excitation threshold as a power function above a critical duty cycle of 0.1%. The threshold reduction was much weaker for symmetrical bipolar nsPEF. Supramaximal stimulation by high-rate nsPEF bursts elicited only a single CAP as long as the burst duration did not exceed the nerve refractory period. Such brief bursts of bipolar nsPEF could be the best choice to minimize neuromuscular stimulation in ablation therapies.

In the present paper the results of a study of new planar composite nanosystems on the basis of complexes formed by amphiphilic polyamine, magnetite nanoparticles, and DNA molecules are presented. Amphiphilic polyamine stearylspermine is synthesized and characterized by the FTIR spectroscopy technique. It is found that a Langmuir monolayer on an aqueous subphase surface can be formed by synthesized stearylspermine molecules. The stearylspermine Langmuir monolayer compression isotherm changes caused by the interaction of a monolayer with colloid magnetite nanoparticles and DNA molecules from the aqueous phase have been studied. The monolayer nanostructures on the surface of mica substrate-Langmuir-Blodgett films of complexes formed by stearylspermine, magnetite nanoparticles, and DNA molecules are formed. The structure of the obtained monolayer films was investigated using the AFM scanning probe technique. Possibilities for the formation of polycomplexes which comprise stearylspermine molecules, functional inorganic nanoparticles, and polymers have been discussed.

Reversing the pulse polarity, i.e., changing the electric field direction by 180°, inhibits electroporation and electrostimulation by nanosecond electric pulses (nsEPs). This feature, known as “bipolar cancellation,” enables selective remote targeting with nsEPs and reduces the neuromuscular side effects of ablation therapies. We analyzed the biophysical mechanisms and measured how cancellation weakens and is replaced by facilitation when nsEPs are applied from different directions at angles from 0 to 180°. Monolayers of endothelial cells were electroporated by a train of five pulses (600 ns) or five paired pulses (600 + 600 ns) applied at 1 Hz or 833 kHz. Reversing the electric field in the pairs (180° direction change) caused 2-fold (1 Hz) or 20-fold (833 kHz) weaker electroporation than the train of single nsEPs. Reducing the angle between pulse directions in the pairs weakened cancellation and replaced it with facilitation at angles <160° (1 Hz) and <130° (833 kHz). Facilitation plateaued at about three-fold stronger electroporation compared to single pulses at 90–100° angle for both nsEP frequencies. The profound dependence of the efficiency on the angle enables novel protocols for highly selective focal electroporation at one electrode in a three-electrode array while avoiding effects at the other electrodes. Nanosecond-resolution imaging of cell membrane potential was used to link the selectivity to charging kinetics by co- and counter-directional nsEPs.

We prepared platinum nanoparticle ink usable for the fabrication of MEMS microheaters of high-temperature gas sensors and thermoresistors operating up to 450 °C and present some preliminary results on the application of the ink in sensor microheater manufacturing. The ink consists of platinum particles (3–8 nm) suspended in ethylene glycol solution of polyvinylpyrrolidone. The ink is usable in both InkJet and AerosolJet printers. The annealing at temperature of about 600 °C leads to the formation of uniform microheater structure. The experiments on microheater aging confirm the stability of the printed microstructure at 450 °C for at least one year of operation. The substrates used for printing were thin alumina and LTCC ceramics with thickness of 12–20 μm.