Development of a carboxyl-terminated Indium Tin Oxide electrode for improving cell adhesion and facilitating low noise, real-time impedance measurements

The working electrode's surface property is crucial to cell adhesion and signal collection in electric cell-substrate impedance spectroscopy (ECIS). To date, the indium tin oxide (ITO) based working electrode is of interest in ECIS study due to its high transparency and biocompatibility. Of great concern is the impedance signal loss, distortion, and data interpretation conflict profoundly created by the movement of multiple cells during ECIS study. Here, a carboxyl- terminated-ITO substrate was prepared by stepwise surface amino silanization, with N-Hydroxy succinimide (NHS), and (1-ethyl-3-(3-dimethyl aminopropyl) carbodiimide hydrochloride) (EDC) treatment, respectively. We investigated the stepwise changes in the property of the treated ITO, cell-substrate adhesion, collective cell mobility, and time course of change in absolute impedance from multiple CHO cells ((Δt-Δ|Z|)CELLS). The carboxyl-terminated ITO substrate with a surface roughness of 6.37 nm shows enhanced conductivity, 75% visible light transparency, improved cell adherence, reduced collective cell migration speed by ~2 fold, and diminished signal distortion in the ((Δt-Δ|Z|)CELLS). Thus, our study provides an ITO surface-treatment strategy to reduce multiple cell movement effects and to obtain essential cell information from the ECIS study of multiple cells through undistorted (Δt-Δ|Z|)CELLS

Fabrication and Photovoltaic Properties of Organic Solar Cell Based on Zinc Phthalocyanine

Herein, we report thin films’ characterizations and photovoltaic properties of an organic semiconductor zinc phthalocyanine (ZnPc). To study the former, a 100 nm thick film of ZnPc is thermally deposited on quartz glass by using vacuum thermal evaporator at 1.5 × 10−6 mbar. Surface features of the ZnPc film are studied by using scanning electron microscope (SEM) with in situ energy dispersive x-ray spectroscopy (EDS) analysis and atomic force microscope (AFM) which reveal uniform film growth, grain sizes and shapes with slight random distribution of the grains. Ultraviolet-visible (UV-vis) and Fourier Transform Infrared (FTIR) spectroscopies are carried out of the ZnPc thin films to measure its optical bandgap (1.55 eV and 3.08 eV) as well as to study chemical composition and bond-dynamics. To explore photovoltaic properties of ZnPc, an Ag/ZnPc/PEDOT:PSS/ITO cell is fabricated by spin coating a 20 nm thick film of hole transport layer (HTL)—poly-(3,4-ethylenedioxythiophene) poly(styrene sulfonic acid) (PEDOT:PSS)—on indium tin oxide (ITO) substrate followed by thermal evaporation of a 100 nm layer of ZnPc and 50 nm silver (Ag) electrode. Current-voltage (I-V) properties of the fabricated device are measured in dark as well as under illumination at standard testing conditions (STC), i.e., 300 K, 100 mW/cm2 and 1.5 AM global by using solar simulator. The key device parameters such as ideality factor (n), barrier height ( ϕ b ), junction/interfacial resistance (Rs) and forward current rectification of the device are measured in the dark which exhibit the formation of depletion region. The Ag/ZnPc/PEDOT:PSS/ITO device demonstrates good photovoltaic characteristics by offering 0.48 fill factor (FF) and 1.28 ± 0.05% power conversion efficiency (PCE), η.

Numerical elimination methods of ITO cell contribution to dielectric spectra of ferroelectric liquid crystals

Indium tin oxide (ITO) electrodes are widely used for liquid crystal applications as well as for measuring cells. Unfortunately, ITO layer possesses its own non zero resistivity R which produces (with the capacity C) the cut-off frequency f0 of RC circuit. Dielectric spectroscopy cannot be performed for high frequencies because of high frequency losses caused by the cell behaviour. Four procedures for estimating and extracting high frequency losses in ITO cells are presented and compared in this paper. Their limitations and viability are discussed.

Comments on R. Karbe and R. L. Kerlin (2002). Cystic Degeneration/Spongiosis Hepatis (Toxicol Pathol 30 (2), 216—227) PETER BANNASCH

Karbe and Kerlin have questioned the classification of spongiosis hepatis as a preneoplastic lesion or even a benign neoplasm, designated as spongiotic pericytoma, and have proposed to use the term cystic degeneration for this lesion in rats and fish. However, the reclassification of spongiosis as cystic degeneration is unwarranted for several reasons. In the rat, spongiosis hepatis represents a specific pathomorphologic entity, originating from the perisinusoidal (Ito) cells; it may occur spontaneously in aged animals but its number and size increases significantly after exposure to various (hepato)carcinogens. Comparative morphological, immunohistochemical, and autoradiographic studies in rats exposed to N-nitrosomorpholine revealed that spongiosis hepatis is an integral part of larger proliferative Ito-cell aggregates showing an autonomous, progressive growth. The classification of spongiosis hepatis as a benign neoplasm is based on these findings that endorse and extend previous considerations on the preneoplastic or neoplastic nature of this lesion. Irrespective of the classification of spongiosis hepatis as a benign neoplastic or a preneoplastic lesion, there is compelling evidence for its reliability as a sensitive marker for (hepato)carcinogenic effects in rats and fish. The data collected by Karbe and Kerlin support rather than contradict the reliability of spongiosis hepatis as an effect marker for carcinogens.