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The authors would like to correct a mistake in Figure 3 as published in the original publication [...].
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Simple carbohydrates are associated with the enhanced risk of cardiovascular disease and adverse changes in lipoproteins in the organism. Conversely, sugars are known to exert a stabilizing effect on biological membranes, and this effect is widely exploited in medicine and industry for cryopreservation of tissues and materials. In view of elucidating molecular mechanisms involved in the interaction of mono- and disaccharides with biomimetic lipid systems, we study the alteration of dielectric properties, the degree of hydration, and the rotational order parameter and dipole potential of lipid bilayers in the presence of sugars. Frequency-dependent deformation of cell-size unilamellar lipid vesicles in alternating electric fields and fast Fourier transform electrochemical impedance spectroscopy are applied to measure the specific capacitance of phosphatidylcholine lipid bilayers in sucrose, glucose and fructose aqueous solutions. Alteration of membrane specific capacitance is reported in sucrose solutions, while preservation of membrane dielectric properties is established in the presence of glucose and fructose. We address the effect of sugars on the hydration and the rotational order parameter for 1-palmitoyl-2-oleoyl-sn-glycero-3- phosphocholine (POPC) and 1-stearoyl-2-oleoyl-sn-glycero-3- phosphocholine (SOPC). An increased degree of lipid packing is reported in sucrose solutions. The obtained results provide evidence that some small carbohydrates are able to change membrane dielectric properties, structure, and order related to membrane homeostasis. The reported data are also relevant to future developments based on the response of lipid bilayers to external physical stimuli such as electric fields and temperature changes.
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In this study, some crucial parameters were determined of flexible polymer-organic solar cells prepared from an active layer blend of poly(3-hexylthiophene) (P3HT) and the fullerene derivative [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) mixed in 1:1 mass ratio and deposited from chlorobenzene solution by spin-coating on poly(ethylene terephthalate) (PET)/ITO substrates. Additionally, the positive effect of an electron transport layer (ETL) prepared from zinc oxide nanoparticles (ZnO np) on flexible photovoltaic elements' performance and stability was investigated. Test devices with above normal architecture and silver back electrodes deposed by magnetron sputtering were constructed under environmental conditions. They were characterized by current-voltage (I-V) measurements, quantum efficiency, impedance spectroscopy, surface morphology, and time-degradation experiments. The control over morphology of active layer thin film was achieved by post-deposition thermal treatment at temperatures of 110-120 °C, which led to optimization of device morphology and electrical parameters. The impedance spectroscopy results of flexible photovoltaic elements were fitted using two R||CPE circuits in series. Polymer-organic solar cells prepared on plastic substrates showed comparable current-voltage characteristics and structural properties but need further device stability improvement according to traditionally constructed cells on glass substrates.
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Scanning electrochemical microscopy (SECM) hybridized with fast Fourier transform-based electrochemical impedance spectroscopy (FFT-EIS) seems to be a powerful variation of scanning electrochemical impedance microscopy (SEIM), wherein both state-of-the-art techniques are combined (FFT-SEIM) and can be used for the investigation and treatment of tissues at single cell level. However, in most EIS-based experiments, harmful redox mediators are applied, which affect the functioning of living cells and tissues. Therefore, the development of a redox-probe-free FFT-SEIM is still a very important challenge in electrochemistry. For this reason, in this research, we have demonstrated a redox-probe-free evaluation of conducting and non-conducting surfaces by combining scanning electrochemical microscopy with FFT-EIS. It was demonstrated that using the fast Fourier transform-based FFT-EIS technique, EIS spectra could be registered much faster compared to experiments performed using the conventional EIS equipment. An ultramicroelectrode (UME) was used as a scanning electrode to ensure high spatial resolution. We have performed FFT-SEIM measurements in a redox-probe-free mode (without any additional redox probes) and have investigated several surfaces with different conductivities. The FFT-EIS equipment and the built-in software help to avoid the influence of possible formation of hydrogen bubbles on the UME. This research opens up a new avenue for the application of FFT-SEIM in the investigation of samples that are unstable and very sensitive towards redox mediators (e.g., tissues and/or living cells).
