Wetting Properties of Simulated and Commercial Contaminants on High Transmittance Superhydrophobic Coating.

The large and necessary diffusion of huge solar plants in extra urban areas implies the adoption of maintenance strategies especially where human intervention would require high costs and logistic problems. Animal dejections like bird droppings and agricultural sprays are environmental agents able to significantly decrease light absorption and, in some cases, cause serious damage to the electric conversion systems in a photovoltaic panel. In this work, the performance of a superhydrophobic (SH) coating in terms of durable self-cleaning properties and transparency has been studied in the presence of commercial and simulated contaminants on glass reference and solar panel surfaces. Wettability studies have been carried out both in static and dynamic conditions in order to compare the compositional effect of commercial liquids used as fertilizers or pesticides and molecules like pancreatin as model substances simulating bird droppings. From these studies, it can be observed that the superhydrophobic coating, independently from the surface where it is applied, is able to repel water and substances used such as fertilizers or pesticides and substances simulating bird droppings, maintaining its properties and transparency. This kind of approach can provide information to design suitable spray formulations without the above-mentioned drawbacks to be used in natural environment areas and agrosolar plants.

Spheroid Formation and Recovery Using Superhydrophobic Coating for Regenerative Purposes.

Cell therapies commonly pursue tissue stimulation for regenerative purposes by replacing cell numbers or supplying for functional deficiencies. To this aim, monodispersed cells are usually transplanted for incorporation by local injection. The limitations of this strategy include poor success associated with cell death, insufficient retention, or cell damage due to shear forces associated with the injection. Spheroids have recently emerged as a model that mimics an in vivo environment with more representative cell-to-cell interactions and better intercellular communication. Nevertheless, cost-effective and lab friendly fabrication and effectively performed recovery are challenges that restrict the broad application of spheroids. In this work, glass surfaces were modified with an environmentally friendly superhydrophobic coating. The superhydrophobic surfaces were used for the 3D spheroid preparation of fibroblasts (3T3 cell line) and keratinocytes (HaCaT cell line). The effectiveness of the spheroids to be recovered and grown under 2D culture conditions was evaluated. The morphology of the migrated cells from the 3D spheroids was characterized at the nano-microscale through 3D profilometry. The results demonstrated improved adhesion and proliferation in the migrated cells, both advanced properties for regenerative applications.

Super Liquid-repellent Surfaces and 3D Spheroids Growth.

Substrates composition and surface features of materials rule adhesion control of cells to surfaces. As a result, most of the aspects of cell functions, such as spreading, migration, proliferation, and differentiation, can be significantly influenced in biomedical applications. Cell cultures make possible to understand cell biology, tissue morphology, mechanisms of diseases, drug action, and tissue engineering development, among others. Recent techniques related to culturing 3D cell aggregates in the presence of very low wettable surfaces represent an innovative field for in vitro experimentation aimed at more reliable conditions to investigate both tumor and non-tumor cell lines. Matching in particular cell biology to innovative materials, this work reviews the recent literature available on promoting cell aggregates formation strongly influenced by the high surface hydrophobicity. In particular, for spheroid formation, the highest water repellent coatings seem to be required for the significant effectiveness of the process. In this way, 3D cell culture has become a reliable method for reproducing in vitro cellular growth in more realistic physiological conditions.

Mammalian Cell Spheroids on Mixed Organic-Inorganic Superhydrophobic Coating.

Three-dimensional cell culture has become a reliable method for reproducing in vitro cellular growth in more realistic physiological conditions. The surface hydrophobicity strongly influences the promotion of cell aggregate formation. In particular, for spheroid formation, highly water-repellent coatings seem to be required for the significant effects of the process. In this work, surfaces at different wettability have been compared to observe their influence on the growth and promotion of aggregates of representative mammalian cell lines, both tumoral and non-tumoral (3T3, HaCat and MCF-7 cell lines). The effect of increased hydrophobicity from TCPS to agarose hydrogel to mixed organic-inorganic superhydrophobic (SH) coating has been investigated by optical and fluorescence microscopy, and by 3D confocal profilometry, in a time scale of 24 h. The results show the role of less wettable substrates in inducing the formation of spheroid-like cell aggregates at a higher degree of sphericity for the studied cell lines.

High transmittance and highly amphiphobic coatings for environmental protection of solar panels.

In this work the authors review the recent literature related to new solutions to prepare coatings with amphiphobic properties in order to provide self-maintaining systems able to limit the human intervention especially in large plants or harsh environments or, generally speaking, to keep the original functionalities of a solar module. Amphiphobic coatings match the requirements preventing both water and oil based pollutants from dust accumulation to natural and urban aerosols, from agriculture dispersions to bird droppings. The increasing need of renewable energy requires this step to be seriously faced with the aim to increase the yield and decrease the modules degradation. Still many issues have to be overcome and here we focus on surface aspects of aging and possible maintenance of the optical features of a solar panel.

3D profilometry and cell viability studies for drug response screening.

In vitro tests for assessing cell viability and drug response are widely employed for determining cytotoxicity of drugs, chemicals, or material substrates. These assays have some advantages, such as speed, reduced cost, and potential for automation. However, since these tests are often run with a huge amount of cells, the characteristic properties of a single cell can be masked leading to a lack of the diagnostic features of these assays. Vital processes as proliferation and cell death (either necrosis or apoptosis) are associated to drastic changes of volume and surface analysis techniques like 3D optical scanning profilometry allow noninvasive and nondestructive approach with fast detection and good resolution at nano-microscale. Here, we demonstrate how coupling noninvasive morphological surface analysis techniques with well assessed biochemical methods can help to establish the relationship between the modifications on cellular viability induced by precursors of proliferation and cell death and variations on cell volume induced by these treatments. The proposed approach has demonstrated improved efficiency on the assessment of inductive changes on tumoral cells in comparison to non-tumoral cells upon administration of proliferative nontoxic or cytotoxic substances like chemotherapeutics.

Mammalian cell viability on hydrophobic and superhydrophobic fabrics.

Surface properties like hydrophobicity and morphology of the substrate are essential for cell proliferation affecting its growth, survival and also for its communication with other cells on fabrics. The combination of low surface energy and a specific surface morphology (micro/nano-roughness) leads to significantly less wettable surfaces, known as superhydrophobic characterized by high contact angle above 150° and a very small hysteresis. Such high water repellent coatings feature small area available to be exploited in many applications where interactions with aqueous environment are strongly to be avoided. In this work, the authors have investigated the influence of coating polyester fabric at different degree of hydrophobicity by mixed organic-inorganic coating with moderated to highly water repellence. Depending on the coating composition and structure, the hydrophobicity of the fabric can be finely modulated by an easy-to-prepare method applicable to commercial, low cost fabric substrates providing advanced performance. In vitro experiments have been performed in order to establish the influence of surface modification on adhesion of representative model mammalian cell lines such as 3T3 fibroblasts, HaCaT keratinocytes and HeLa epithelial carcinoma cells. The obtained results suggested that, in addition to the chemistry and morphology of the coating, the characteristics of the substrate are important parameters on the final cell viabilities.

Potentiodynamic study of Al-Mg alloy with superhydrophobic coating in photobiologically active/not active natural seawater.

Superhydrophobic coating technology is regarded as an attractive possibility for the protection of materials in a sea environment. DC techniques are a useful tool to characterize metals' behavior in seawater in the presence/absence of coatings and/or corrosion inhibitors. In this work, investigations concerning Al-5%Mg alloy with and without a sprayed superhydrophobic coating were carried out with potentiodynamic scans in photobiologically active and not active seawater (3 weeks of immersion). In not photobiologically active seawater, the presence of the superhydrophobic coating did not prevent pitting corrosion. With time, the coating underwent local exfoliations, but intact areas still preserved superhydrophobicity. In photobiologically active seawater, on samples without the superhydrophobic coating (controls) pitting was inhibited, probably due to the adsorption of organic compounds produced by the photobiological activity. After 3 weeks of immersion, the surface of the coating became hydrophilic due to diatom coverage. As suggested by intermediate observations, the surface below the diatom layer is suspected of having lost its superhydrophobicity due to early stages of biofouling processes (organic molecule adsorption and diatom attachment/gliding). Polarization curves also revealed that the metal below the coating underwent corrosion inhibiting phenomena as observed in controls, likely due to the permeation of organic molecules through the coating. Hence, the initial biofouling stages (days) occurring in photobiologically active seawater can both accelerate the loss of superhydrophobicity of coatings and promote corrosion inhibition on the underlying metal. Finally, time durability of superhydrophobic surfaces in real seawater still remains the main challenge for applications, where the early stages of immersion are demonstrated to be of crucial importance.

Toxicity study in blood and tumor cells of laser produced medicines for application in fabrics.

Phenothiazine derivatives are non-antibiotics with antimicrobial, fungistatic and fungicidal effects. We exposed to a high energy UV laser beam phenothiazines solutions in water at 20mg/mL concentration to increase antibacterial activity of resulting mixtures. Compared to previous results obtained on bacteria, more research is needed about UV laser irradiated phenothiazines applications on cancer cell cultures to evidence possible anticancerous properties. Evaluation of the safety of the newly obtained photoproducts in view of use on humans is also needed. Due to expensive animal testing in toxicology and pressure from general public and governments to develop alternatives to in vivo testing, in vitro cell-based models are attractive for preliminary testing of new materials. Cytotoxicity screening reported here shows that laser irradiated (4h exposure time length) chlorpromazine and promazine are more efficient against some cell cultures. Interaction of laser irradiated phenothiazines with fabrics show that promethazine and chlorpromazine have improved wetting properties. Correlation of these two groups of properties shows that chlorpromazine appears to be more recommended for applications on tissues using fabrics as transport vectors. The reported results concern stability study of phenothiazines water solutions to know the time limits within which they are stable and may be used.