Changes in temperature inside an optomechanical model of the human eye during emulated transscleral cyclophotocoagulation.

Currently, many diseases of the eye are treated by laser surgery. An understanding of light propagation and the heating of eye tissue during laser exposure is crucial to improving the outcome of these procedures. Here, we present the development of physical and computational models of the human eye by combining optical light propagation and thermal characteristics. For the physical model, all parts of the eye, including cornea, lens, ciliary body, sclera, aqueous and vitreous humors, and iris, were fabricated using a 3D printed holder and modified polydimethylsiloxane. We also present a computational model based on finite element analysis that allows for a direct comparison between the simulation and experimental measurements. These models provide an opportunity to directly assess the rise in temperature in all eye tissues. The simulated and physical models showed good agreement for the transmission of light at varying incident angles. The heating of optical components was investigated in the retina and the ciliary body during simulated laser surgery. Temperature increases of 45.3°C and 30.6°C in the retina and ciliary bodies, respectively, were found in the physical model after 1 minute of exposure to 186 mW of 850 nm laser radiation. This compared to 29.8°C and 33.9°C increases seen under the same conditions in the simulation model with human eye parameters and 48.1°C and 28.7°C for physical model parameters. These results and these models are very promising for further investigation of the impact of laser surgery.

Determination of optical parameters of the porcine eye and development of a simulated model.

The eye is a very sophisticated system of optical elements for the preeminent sense of vision. In recent years, the number of laser surgery to correct the optical aberration such as myopia or astigmatism has significantly increased. Consequently, improving the knowledge related to the interactions of light with the eye is very important in order to enhance the efficiency of the surgery. For this reason, a complete optical characterization of the porcine eye is presented in this study. Kubelka-Munk and Inverse Adding-Doubling methods were applied to spectroscopy measurement to determine the absorption and scattering coefficients. Furthermore, the refractive index has been measured by ellipsometry. The different parameters were obtained for the cornea, lens, vitreous humor, sclera, iris, choroids and eyelid in the visible and infrared region. Thereafter, the results are implemented in a COMSOL Multiphysics® software to create an eye model. This model gives a better understanding of the propagation of light in the eye by adding optical parts such as the iris, the sclera or the ciliary bodies. Two simulations show the propagation of light from the cornea to the retina but also from the sclera to the retina. This last possibility provides a better understanding of light propagation during eye laser surgery such as, for example, transscleral cyclophotocoagulation. Figure: Eye simulation models allow the development of new laser treatments in a simple and safe way for patients. To this purpose, the creation of an eye simulated model based on optical parameters obtained from experimental data is presented in this study. This model will facilitate the understanding of the light propagation inside the porcine eye.

Effect of E Cigarette Emissions on Tracheal Cells Monitored at the Air-Liquid Interface Using an Organic Electrochemical Transistor.

E-cigarettes have been suggested as a potentially healthier alternative to cigarettes based on studies using cell viability, DNA damage, and transcriptional response assays. However, little is known about the effect of e-cigarette aerosols on the integrity of the tracheal epithelium, specifically with respect to barrier resistance. This is partly due to the lack of methods for monitoring epithelia at the air-liquid interface (ALI), i.e., under physiological conditions. Here, it is shown that an organic electrochemical transistor can be adapted for the measurement of barrier resistance at the ALI. This technology enables accurate, continuous quantification of tracheal barrier integrity through the use of a conformable gate electrode placed on top of the cell-secreted mucus, obviating the need for addition of culture medium or buffer as a conductance medium for rigid electrodes. This platform allows for the detection of a dose-dependent, rapid decrease in barrier resistance of an in vitro model of human bronchial epithelium (MucilAir) after E-cigarette aerosols exposure. The system represents a powerful tool to study tissue responses of the human airway epithelium to inhaled smoke. The same technology will have broad applications for toxicology studies on other tissues with ALI, including other airway tissues and skin.

Profiling the biological effects of wastewater samples via bioluminescent bacterial biosensors combined with estrogenic assays.

Various water samples were successfully evaluated using a panel of different recombinant bioluminescent bacteria and estrogenic activity analysis. The bioluminescent bacteria strains induced by oxidative (superoxide radical or hydroxyl radical), protein damage, cell membrane damage, or cellular toxicity were used. Estrogenic activities were examined by using the yeast strain BY4741, which carries the ß-galactosidase reporter gene under the control of the estrogen-responsive element (ERE). A total of 14 samples from three wastewater treatment plants, one textile factory, and seawater locations in Tunisia were analyzed. A wide range of bio-responses were described. Site/sample heterogeneity was prevalent, in combination with generally high relative bioluminescence scores for oxidative stress (OH•). Estrogenic activity was detected at all sites and was particularly elevated at certain sites. Our perspectives include the future exploration of the variation detected in relation to treatment plant operations and environmental impacts. In conclusion, this new multi-experimental method can be used for rapid bio-response profile monitoring and the evaluation of environmental samples spanning a wide range of domains. This study confirms that bio-reactive wastewater treatment plant (WWTP) effluents are discharged into seawater, where they may impact coastal populations.

Optimization of a planar all-polymer transistor for characterization of barrier tissue.

The organic electrochemical transistor (OECT) is a unique device that shows great promise for sensing in biomedical applications such as monitoring of the integrity of epithelial tissue. It is a label-free sensor that is amenable to low-cost production by roll-to-roll or other printing technologies. Herein, the optimization of a planar OECT for the characterization of barrier tissue is presented. Evaluation of surface coating, gate biocompatibility and performance, and optimization of the geometry of the transistor are highlighted. The conducting polymer poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate), which is used as the active material in the transistor, has the added advantage of allowing significant light transmission compared to traditional electrode materials and thus permits high-quality optical microscopy. The combination of optical and electronic monitoring of cells shown herein provides the opportunity to couple two very complementary techniques to yield a low-cost method for in vitro cell sensing.

Combined optical and electronic sensing of epithelial cells using planar organic transistors.

A planar, conducting-polymer-based transistor for combined optical and electronic monitoring of live cells provides a unique platform for monitoring the health of cells in vitro. Monitoring of MDCK-I epithelial cells over several days is shown, along with a demonstration of the device for toxicology studies, of use in future drug discovery or diagnostics applications.