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Two-dimensional graphitic carbon, graphene, is a new form of nanomaterial with great potential in a wide variety of applications. It is therefore crucial to investigate the behaviour of graphene in biological systems to assess potential adverse effects that might follow from inhalation exposure. In this study we focussed on medium-term effects of graphene in lung tissue by investigating the pulmonary inflammation 6 weeks after pharyngeal aspiration of unoxidised multilayered graphene platelets (GPs) in mice and assessed their biopersistence in the lung tissue using Raman spectroscopy. Additionally, GP degradation in vitro was examined after horseradish peroxidase (HRP) treatment up to 1 week. Building on our previous report showing acute inflammation in mice lungs at 1 day, pristine GP showed minimal inflammation in mouse lungs after 6 weeks even though no degradation of GP in lung tissue was observed and large deposits of GP were evident in the lungs. Raman analysis of GP in tissue sections showed minimal oxidation, and in vitro examinations of enzymatic oxidation of GP via HRP and H2O2 showed only slight increases in ID/IG ratio and the appearance of the Raman D' band at 1620 cm(-1) (surrogates of graphene oxidation). Our results showing non-inflammogenicity at medium time points have important implications in the hazard identification of GPs following inhalation exposure and for their use in biomedical applications. Additionally, the biopersistence of pristine GP in vivo with no associated inflammation could open the way to applications in tissue engineering and drug delivery.

Monodisperse nanosuspension droplets, placed on a flat surface, evaporated following the stick-slip motion of the three-phase contact line. Unexpectedly, a disordered region formed at the exterior edge of a closely packed nanocolloidal crystalline structure during the "stick" period. In order to assess the role of particle velocity on particle structuring, we did experiments in a reduced pressure environment which allowed the enhancement of particle velocity. These experiments revealed the promotion of hexagonal packing at the very edge of the crystallite with increasing velocity. Quantification of particle velocity and comparison with measured deposit shape for each case allowed us to provide a tentative description of the underlying mechanisms that govern particle deposition of nanoparticles at the triple line of an evaporating droplet. Behavior is governed by an interplay between the fluid, and hence particle, flow velocity (main ordering parameter) and wedge constraints, and consequently disjoining pressure (main disordering parameter). Furthermore, the formation of a second disordered particle region at the interior edge of the deposit (towards bulk fluid) was found and attributed to the rapid motion of the triple line during the "slip" regime. Additionally, the magnitude of the pinning forces acting on the triple line of the same drops was calculated. These findings provide further insight into the mechanisms of the phenomenon and could facilitate its exploitation in various nanotechnological applications.

Non-wetting surfaces engineered from intrinsically hydrophilic metallic materials are promising for self-cleaning, anti-icing and/or condensation heat transfer applications where the durability of the coating is an issue. In this work, we fabricate two metallic non-wetting surfaces with varying number and size of the roughness tiers without further hydrophobic coating procedure. The wetting behaviour and the condensation performance is then addressed.On one hand, the surface resembling a rose petal exhibits a sticky non-wetting behaviour as drops wet the microscopic roughness features with the consequent enhanced drop adhesion. In turn, this stickiness leads to filmwise condensation. On the other hand, the surface resembling a lotus leaf provides super-repellent non-wetting behaviour prompting the continuous nucleation, growth and departure of spherical drops in a dropwise condensation fashion. The additional oxidation step, which creates a third nano-scale roughness tier on the surface resembling a lotus leaf, is found to be paramount in prompting the growth of drops in the Cassie state with the benefit of minimal condensate adhesion. The two different condensation behaviours reported are well supported by a drop surface energy analysis, which accounts for the different wetting performance and the surface structure underneath the condensing drops. Further, we coated the above-mentioned surfaces with polydimethylsiloxane surfaces, which resulted in filmwise condensation due to the smoothening of the different roughness tiers. The first, to the best of our knowledge, continuous dropwise condensation on a metallic surface without the need for a conformal hydrophobic coating is hence demonstrated, which offers a novel path for the design and manufacture of non-coated metallic super-repellent surfaces for condensation phase change applications, amongst others.