Spatiotemporal 3D cell impedance monitoring for metal nanoparticle risk assessment by plug-in vertical electrode array.

Metal nanoparticles are commonly found in our daily lives and pose great risks to people's health. Therefore, it is crucial to establish a research model for the toxic effects of metal nanoparticles. In recent decades, three-dimensional (3D) cell models have attracted increasing interest in the fields of cell barriers, nanotoxicology, and drug screening, as they have significant advantages over two-dimensional (2D) cell models in accurately simulating behavior of human cells.

Real-time cell barrier monitoring by spatial transepithelial electrical resistance measurement on a microelectrode array integrated Transwell.

Transepithelial electrical resistance (TEER) measurement is a label free, rapid and real-time technique, which is commonly used to evaluate the integrity of cell barriers. TEER characterization is important for applications, such as tissue (brain, intestines, lungs) barrier modeling, drug screening, and cell growth monitoring. Traditional TEER methods usually only show the average impedance of the whole cell layer, and lack accuracy and the characterization of internal spatial differences within cell layer regions.

Exosomal membrane proteins analysis using a silicon nanowire field effect transistor biosensor.

Exosomes are of great significance in clinical diagnosis, due to their high homology with parental generation, which can reflect the pathophysiological status. However, the quantitative and classification detection of exosomes is still faced with the challenges of low sensitivity and complex operation. In this study, we develop an electrical and label-free method to directly detect exosomes with high sensitivity based on a Silicon nanowire field effect transistor biosensor (Si-NW Bio-FET).

Volatile carbonyl metabolites analysis of nanoparticle exposed lung cells in an organ-on-a-chip system.

The evaluation of nanoparticles (NPs) cytotoxicity is crucial for advancing nanotechnology and assessing environmental pollution. However, existing methods for NPs cytotoxicity evaluation suffer from limited accuracy and inadequate information content. In the study, we developed a novel detection platform that enables the identification of cellular carbonyl metabolites at the organ level.

Real-time measurement of the trans-epithelial electrical resistance in an organ-on-a-chip during cell proliferation.

The trans-epithelial electrical resistance (TEER) is widely used to quantitatively evaluate cellular barrier function at the organ level . The measurement of the TEER in organ-on-chips (organ chips) plays a significant role in medical and pharmacological research. However, due to the limitation of the electrical equivalent model for organ chips, the existing TEER measurements usually neglect the changes of the TEER during cell proliferation, resulting in the low accuracy of the measurements.

Collisional dynamics in laser-induced plasmas: evidence for electron-impact excitation.

We have experimentally investigated the collisional dynamics in femtosecond-laser-induced plasmas and presented the evidence for electron-impact excitation through enhanced high-order harmonic (HH) generation. The measurements were carried out by using an elliptically polarized pump pulse to induce the underdense plasmas and by using a time-delayed linearly polarized probe pulse to drive the HH generation from the plasmas. We found that the rise time of this enhanced HH generation was insensitive to the ellipticity degree (ED) of pump pulse but sensitive to its laser intensity (LI).

Probing electron-atom collision dynamics in gas plasma by high-order harmonic spectroscopy.

Plasma is a complex system involving diverse collisional processes and interactions, such as electron-impact excitation, ionization, recombination, etc. One of the most important methods for studying the properties and dynamics of plasma is to analyze the radiations from plasma. Here, we demonstrate the high-order harmonic (HH) spectroscopy for probing the complex electron-atom collision (EAC) dynamics in a laser-induced gas plasma.

Ultrafast molecular orbital imaging based on attosecond photoelectron diffraction.

We present ab initio numerical study of ultrafast ionization dynamics of H(2)(+) as well as CO(2) and N(2) exposed to linearly polarized attosecond extreme ultraviolet pulses. When the molecules are aligned perpendicular to laser polarization direction, photonionization of these molecules show clear and distinguishing diffraction patterns in molecular attosecond photoelectron momentum distributions. The internuclear distances of the molecules are related to the position of the associated diffraction patterns, which can be determined with high accuracy.

Probing rotational wave-packet dynamics with the structural minimum in high-order harmonic spectra.

We investigate the alignment-dependent high-order harmonic spectrum generated from nonadiabatically aligned molecules around the first half rotational revival. It is found that the evolution of the molecular alignment is encoded in the structural minima. To reveal the relation between the molecular alignment and the structural minimum in the high-order harmonic spectrum, we perform an analysis based on the two-center interference model.

Influence of large permanent dipoles on molecular orbital tomography.

The influence of large permanent dipoles on molecular orbital tomography via high-order harmonic generation (HHG) is investigated in this work. It is found that, owing to the modification of the angle-dependent ionization rate resulting from the Stark shift, the one-side-recollision condition for the tomographic imaging can not be satisfied even with the few-cycle driving pulses. To overcome this problem, we employ a tailored driving pulse by adding a weak low-frequency pulse to the few-cycle laser pulse to control the HHG process and the recollision of the continuum electrons are effectively restricted to only one side of the core.

Quantum-orbit analysis for yield and ellipticity of high order harmonic generation with elliptically polarized laser field.

We perform a quantum-orbit analysis for the dependence of high-order-harmonic yield on the driving field ellipticity and the polarization properties of the generated high harmonics. The electron trajectories responsible for the emission of particular harmonics are identified. It is found that, in elliptically polarized driving field, the electrons have ellipticity-dependent initial velocities, which lead to the decrease of the ionization rate.

Tomographic imaging of asymmetric molecular orbitals with a two-color multicycle laser field.

We theoretically demonstrate a scheme for tomographic reconstruction of asymmetric molecular orbitals based on high-order harmonic generation with a two-color multicycle laser field. It is shown that by adjusting the relative phase of the two fields, the returning electrons can be forced to recollide from one direction for all the orientations of molecules. Thus, the reconstruction of the asymmetric orbitals can be carried out with multicycle laser field.

Imprints of the molecular-orbital geometry on the high-harmonic ellipticity.

The influence of the orbital symmetry on the ellipticity of the high-order harmonics is investigated. It is found that the ellipticity maps have distinct shapes for the molecular orbitals with different symmetry. Our analysis shows that the feature of the harmonic ellipticity map is essentially determined by the nodal structure of the nonsymmetric orbital.

Broadband large-ellipticity harmonic generation with polar molecules.

We investigate the polarization properties of high harmonic generation from polar molecules with a linearly polarized field. It is found that elliptically polarized harmonics are observed in a wide spectral range from the plateau to the cutoff. Further analyses show that the nonsymmetric structure of the highest occupied molecular orbital is the origin of ellipticity of the harmonics.