A novel impedimetric sensor based on N-acetyl-L-cysteine for the determination of hydroxyl radicals in cell cultures in vitro.

We report a novel impedimetric sensor based on a graphite electrode impregnated with polyethylene and paraffin under vacuum (IGE) modified with electrochemically deposited gold and a self-assembled monolayer of N-acetyl-L-cysteine (NAC/Au/IGE) for selective and sensitive determination of extracellular hydroxyl radicals (OH•) generated by living cells. The application of a sulphur-containing molecule oxidized by OH• predicts the high selectivity of the sensor, and the utilization of the non-faradaic impedance spectroscopy for recording an analytical response makes it possible to achieve superior sensitivity with a detection limit of 0.01 nM and a linear dynamic range of 0.08-8 nM. Meanwhile, NAC/Au/IGE demonstrated a strong potential of detecting OH• generated by biological objects via successful determination of extracellular hydroxyl radicals generated by normal fibroblast cells and prostate carcinoma cells.

Soliton dynamics in media with space stimulated Raman scattering and synchronic spatial variation of dispersion and self-phase modulation.

Solitons dynamics in the frame of the extended nonlinear Schrödinger equation taking into account space stimulated Raman scattering (SSRS), synchronic spatial variation of inhomogeneous second-order dispersion (SOD), and self-phase modulation (SPM) is considered both analytically and numerically. Compensation of soliton Raman self-wave number down shift by synchronically increasing SOD and SPM is shown. Analytical soliton solution as a result of the equilibrium of SSRS and increasing both SOD and SPM is found. Regime of the dynamical equilibrium of SSRS and inhomogeneous media with periodical variation of soliton's parameters is found. Analytical and numerical results are in a good agreement.