Cell-based therapies have a relatively long tradition in modern medicine. Since the 70s surgeons tried to treat malignant and non-malignant disease with direct injection of bone marrow cells. Other cell-based therapies have been proposed after these initial achievements, but it was only in the late eighties that a new concept of therapy, based on cells, has been organically developed. In that years, R. Langer, J. and C. Vacanti proposed the combined use of cells and materials (i.e., scaffolds) to repair tissues and organs, so overcoming the several problems associated with the use of transplants. They coined the term “tissue engineering” as “an interdisciplinary field that applies the principles of engineering and life sciences toward the development of biological substitutes that restore, maintain, or improve tissue function or a whole organ”. The practical application of these concepts started at the Howard Green & Associates with the researches on cultured sheets of autologous epidermis transplanted to patients suffering from different types of skin lesions1. Other remarkable examples followed this initial attempt. Autologous osteoblast cells, taken from the periosteum and seeded into coral scaffolds, have been used to reconstruct the traumatically lost thumb of a patient. Occluded pulmonary arteries, replaced with a polycaprolactone-polyglycolic acid copolymers scaffold, seeded with own patient peripheral blood vessels cells, gave positive results. Similarly, isolated vascular smooth muscles and endothelial cells were used to reconstruct arteries. Another example is the attempted substitution of surgical bladder augmentation in favour of tissue engineered bladders made by collagen in which urothelial and smooth muscle cells have been seeded. The therapeutic approaches on which tissue engineering has been initially based can be divided in two major techniques: i) the use of scaffold embedded with cells that adhered and proliferated in it and ii) direct seeding of isolated cells in the injured part to promote regeneration. In more recent time, however, an new approach has been developed by a Japanese research group coordinated by prof. Okano. This has been named by him “cell sheet engineering”. The technique is based on the possibility to harvest an undamaged sheet of cells that can be directly transplanted to the injured organ and promote its recovery. Cell sheet engineering possess some advantages over the other techniques as will be clear from the next chapter. Nevertheless, it needs to be improved and, in particular, further studies are necessary to better comprehend the mechanisms by which the cell layer is harvested. This process is based on the behaviour of a “smart polymer” called poly(N-isopropylacrylamide) (PNIPAM) that is capable to trigger cells adhesion simply varying temperature. At 37 °C, cells can adhere and proliferate on substrates grafted with this peculiar polymer, but, once temperature is decreased, it modifies its structure causing cell detachment. If the cells are confluent, then a cell sheet can be harvested and, consequently, used for tissue engineering applications. The focus of the present work has been the study and characterization of smart substrates employed for cell sheet engineering. A general overview on tissue engineering and “cell sheet engineering” applications are summarized in the background (Chapter 1). The state of the art on the different substrates employed and the behaviour of smart polymer are introduced. The general introduction is concluded with the basic concepts on the synthesis route adopted (Chapter 2). The experimental section is divided in two distinct parts: 1) the first part (Chapter 3) is focused on PNIPAM. A deeper description of the characteristics and the applications for this polymer are presented in a brief introduction. Then, the synthesis and general characterization of the polymer are discussed. The smart properties of tethered PNIPAM are tested by in vitro cell cultures and cell sheets, harvested from the obtained samples, characterized. The behaviour of the outermost region of the PNIPAM-coating are deeply investigated by means of Wilhelmy plate technique. A possible model for the evolution of the observed phenomena is given. In the end, an analysis related to the influence of PNIPAM thickness is presented. In particular, the correlation between the polymer chins length and the smart behaviour is investigated by cell culture test and dynamic contact angle. 2) The second part of the of the work (Chapter 4) is dedicated to a different approach to obtain a cell sheet. In the initial section of the chapter, a possible electroactive substrate is examined as an alternative to PNIPAM. The unexpected results, however, led to a different strategy that is presented. Despite limited to a specific cell line, this method allowed for a simple cell sheet harvesting that is described. A possible application is proposed and the characterization of the substrates used for this approach are exposed. Finally, the biological response and the cell sheets obtained by this method are studied.

Ultrafine grained (~ 1μm) steels have been the subject of extensive research work during the past years. These steels generally offer interesting perspectives looking for improved mechanical properties. UFG Powder Metallurgy hot work tool steels (HWTS) can be fabricated by high energy mechanical milling (MM) followed by spark plasma sintering (SPS). However, similarly to most UFG and Nano-Crystalline (NC) metals, reduced ductility and toughness result from the early plastic instabilities in these steels. Industrialization of UFG PM Tool Steels requires the application of specific metallurgical tailoring to produce tools with sound mechanical properties or in a more optimistic way, to break the Strength-Toughness “trade-off†in these materials. Among the possible ways proposed to restore ductility and toughness without losing the high strength, “Harmonic microstructure†design seems to be a very promising endeavor in this regard. Harmonic microstructure materials consist of a tunable volume fraction of evenly spaced “isolated†coarse-grained particles (CG) surrounded by a 3D interconnected network of UFG particles. CGs provide ductility and toughness, while high strength is guaranteed by the interconnected network of UFGs. This peculiar design offers an extra work hardening due to the generation of geometrically necessary dislocations at the interfaces of UFGs and confined CGs that are essentially present to accommodate the strain gradient imposed by the inhomogeneous (bimodal grained) microstructure. The first part of this work is devoted to the development of PM tool steels with harmonic microstructure. Due to the difficulties of processing hard tool steel particles according to the methods reported in the literature, an economical, simple alternative approach is also proposed. Near full density “Harmonic structure“ AISI H13 samples were produced using different volume fractions of UFG/NC mechanically milled (MM) and CG as-atomized particles followed by short time (30 min) low-temperature (1100°C) SPS. A combination of high hardness and significantly improved fracture toughness was achieved for the blends containing more that 50% UFG particles. The optimized mechanical properties was achieved by the mixture of 60% UFG particles where the sample showed a hardness near to the value predicted by the rule of mixtures (i.e. 405 HV10 vs. 406 HV10) while apparent fracture toughness (Kapp) was about 10% higher than that of predicted by the same rule (i.e. 52.0 MPa*m1/2 vs. ~47.0 MPa*m1/2). A toughening effect was evidenced for the samples essentially showing harmonic microstructure. Toughening was interpreted to be the result of the deviatory effect of coarse-grained round atomized particles together with energy dissipation by decohesion at the CG/UFG or UFG/UFG interfaces leading to a local drop of the driving force for the crack propagation. The design allowed to easily adjust the strength and toughness to meet the specific application-oriented requirements. The harmonic steel was also subjected to Thermal Fatigue (TF) testing. The preliminary results confirmed that this microstructure combined the beneficial effects of both of its constituents, i.e., the low crack nucleation rate of CG H13 and the low crack propagation rate of UFG H13, thus showing the lowest pyrocracking factor. Moreover, TF crack deflection as an extrinsic toughening mechanism was evidenced in Harmonic Microstructure. The second part of this work deals with the production and characterization of a PM HWTS reinforced with partially stabilized zirconia (PSZ). HWTS composites show improved hardness and remarkable wear resistance but generally also a systematic lower fracture toughness than the base material. Deteriorated toughness in metal matrix composites (MMCs) with a high strength matrix is mainly interpreted as a result of early damage initiation at the hard particles (HPs) or Matrix-HP interface. This damage can be even anticipated in the presence of readily damaged HPs (i.e. processing related flaws). Selection of PSZ as reinforcement was aimed at improving the strength and fracture toughness of the composite by taking advantage of the transformation toughening effect of PSZ. Two different types of PSZ, different volume fractions (10 and 20 vol. %) and sizes of reinforcement were used. Mechanical Alloying (MA) was used to process the composite powders to refine the matrix microstructure and both the matrix and PSZ particle size hence increasing the strength of the PSZ particles according to the Griffith strength formalism, and also to overcome the aggregation problems. Powders were consolidated by (SPS). The influence of processing parameters on density and microstructure was investigated. Short time (30 min) low-temperature (1100°C) consolidation by SPS allowed preserving the refined microstructure while achieving a maximum relative density of 98.6%. Moreover, short time sintering did not allow the extensive formation of thermodynamically plausible reaction products at the PSZ-H13 interface. As a result of dispersion hardening, the hardness of the as-sintered composites (i.e. maximum hardness of ~ 920 HV10) was increased compared to the mechanically milled UFG H13 (i.e. ~ 755 HV10), while in comparison to the as-atomized H13 (i.e. ~ 640 HV10) the improved hardness was ascribed to the synergic effect of dispersion hardening, microstructural refinement and strain hardening induced by MA. In these composites, tempering resistance at 550°C and 650°C was significantly improved due to the dispersion hardening effect. The hot compressive yield strength of the composites at 650°C and 450°C was increased up to 1.8 times the unreinforced UFG H13. t to m transformation during hot compression was evidenced and contributed to the strengthening. The hardness of the composites in heat treated condition (i.e. ~ 600 HV10) was significantly improved compared to that of the unreinforced matrix (i.e. ~ 420 HV10) while the apparent fracture toughness was drastically decreased to half the Kapp of the base material (19 MPa*m1/2 vs. 36 MPa*m1/2). However, the fracture toughness was slightly higher than that of a TiC reinforced H13 (i.e. 17 MPa*m1/2) with the same hardness (i.e. ~ 600 HV10).

A computer aided manufacturing approach to encapsulate viable mammalian cells in hydrogels and use these capsules as the building blocks for scaffolds. A novel 3D capable contactless bioprinter is presented that encapsulates cells in a alginate hydrogel through an electro hydro dynamic process and deposit these capsules on a specifically engineered substrate manufacturing scaffold without the need for further postprocessing.

The thesis work aimed to find appropriate syntheses procedures for the preparation of Nano Building Blocks (NBB) and Nano Particles (NP), starting from organo silanes as molecular precursors, using the Sol-Gel method. NBB were obtained by either non-hydrolytic or in situ water production (ISWP) route, depending on the reactive function’s loading. The obtained NBB were characterised by means of FT-IR, ATR/FT-IR, RAMAN, multinuclear NMR spectroscopies, SEM, N2 physisorption, Thermal analyses (TG/DTA), DSC. NBBs were used to prepare methacrylate-based matrices, which were subsequently exploited in order to produce patternable films by the two photon polymerisation technique (TPP). Epoxy-based matrices were also prepared and the films obtained were patterned by the UV photolithography technique. Both techniques gave high surface resolution patterning. NP were obtained with a modified Stöber method and organosilica NP were obtained. The NP were characterised by FT-IR and NMR spectroscopies. Morphology was observed and sizes calculated using SEM; N2- physisorption and thermal analyses (TG/DTA) were also carried out in order to complete the characterization. DSC measurements were performed on methacryloxypropyl-functionalised NP in order to control the ability to polymerise of the particles. Films of the different organic-modified NP were obtained by spin coating and contact angle measurements were performed. FE-SEM was used in order to observe an eventual change in morphology after thermal treatment under reduced atmosphere. The ability to retain the shape depends on the functional group on the NP. Finally a preliminary study on dye doping was accomplished. The NP were efficiently doped with a fluorescent dye: Rhodamine 6G (R6G). Absorption and emission spectra were recorded with a spectrofluorometer. It is observable that the emission spectra is influenced by the NP’s matrix.

Atomistic simulations based on Molecular Dynamics (MD) were used to model the lattice distortions in metallic nano-polycrystalline microstructures, with the purpose of supporting the analysis of the X-ray powder diffraction patterns with a better, atomic level understanding of the studied system. Complex microstructures were generated with a new modified Voronoi tessellation method which provides a direct relation between generation parameters and statistical properties of the resulting model. MD was used to equilibrate the system: the corresponding strain field was described both in the core and in surface regions of the different crystalline domains. New methods were developed to calculate the strain tensor at the atomic scale. Line Profile Analysis (LPA) was employed to retrieve the microstructure information (size and strain effects) from the powder diffraction patterns: a general algorithm with an atomic level resolution was developed to consider the size effects of crystalline domains of any arbitrary shape. The study provided a new point of view on the role of the grain boundary regions in nano-polycrystalline aggregates, exploring the interference effects between different domains and between grain boundary and crystalline regions. Usual concepts of solid mechanics were brought in the atomistic models to describe the strain effects on the powder diffraction pattern. To this purpose the new concept of Directional - Pair Distribution Function (D-PDF) was developed. D-PDFs calculated from equilibrated atomistic simulations provide a representation of the strain field which is directly comparable with the results of traditional LPA (e.g. Williamson-Hall plot and Warren-Averbach method). The D-PDF opens a new chapter in powder diffraction as new insights and a more sound interpretation of the results are made possible with this new approach to diffraction LPA.

This thesis describes the work of my Ph.D studies in Industrial Engineering during past three years. It regards preparation of copper-tin alloys from green solvents for decorative purposes. Actual industrial process involves cyanide based complex bath in order to produce white bronze layers and they often contain lead as brightener and whitener. The aim of the thesis is to develop a more environmental friendly process for white bronze electrodeposition. Two different electrolytes were considered as eligible candidates: one involves a simple organic acid aqueous solution as bulk electrolyte, and the other one is a new deep eutectic solvent bath. The investigation of electrodeposition using methanesulfonic acid as complexing agent considered a commercial bath and its optimization in order to be used in the decorative industry. The focus of the study was on the optimization of deposition parameters and verification of bath and deposit stability which was very important from industrial point of view. Obvious improvements on deposits quality and bath stability can be realized by replacement on anode material and utilization of pulse current. Contrary to that, research on electrodeposition from deep eutectic system was quite new and few relevant studies can be referred especially in the field of alloys. As a result, this work started from deposition of single metal for better understanding of behaviors of mixtures between choline chloride and ethylene glycol or urea. Successful deposition of copper-tin alloys can be carried out under warmed conditions and variation on film composition can be controlled by changing concentrations of metallic salts in the bath. Pulse current acted as an effective tool to refine microstructure of deposits in a similar way as in aqueous solvents. Since no brightener was added, reduced luster was observed here and working mechanism of additives was found to be rather different from that in conventional baths. In summary, operation parameters including temperature, salt concentration, anode material and supporting electrolytes influence the resultant properties of deposits in great extent. Deposit quality from both solvents can be improved by using pulse current with proper frequency.

The European Union has undertaken several efforts to reduce the non-exhaust particulate matter emissions from road vehicles. One of the major sources of these emissions is the wear of brake pads and discs. The experimental work presented in this thesis has been performed within the European project called LOWBRASYS that aims at reducing the particulate matter emissions due to the wear of the components of braking systems. Different strategies have been identified for reaching this aim but the present work focuses on the investigation of the wear mechanisms at the disc-pad interface and on their role on the emission in the atmosphere and in the environment of wear debris. In order to achieve the reduction in the particulate matter emissions, the traditional gray cast iron discs have been coated with different cermet coatings deposited via high velocity oxygen fuel (HVOF) process. A further attempt for improving the wear resistance of the gray cast iron discs was performed by applying on them an industrial heat treatment. The cermet coatings have been widely employed in the field of the oil and gas industry for improving the wear resistance and the service life of valves and pipes but their use in the field of road-vehicles-braking-systems has never been explored so far. The present work focuses on the tribological characterization of HVOF coated and heat treated discs performed by means of laboratory-scale-pin-on-disc tribometers at both room and high temperatures (300°C). The sliding speed of 1.57 m/s and the nominal contact pressure of 1 MPa used for this characterization have been selected in order to replicate the actual contact conditions between brake pads and brake discs during an urban cycle braking action. Since the use of lab-scale experimental apparatuses, these tests have not been meant to reproduce real braking conditions for which specific dyno bench tests have been performed in further characterization tests. The pins used during the PoD characterization, made of three different commercially-available friction materials, had dimensions of 12 mm in height and 6 and 10 mm in diameter. The discs, 6 mm in thickness and 58.9 mm in diameter, were coated with a 70 µm thick layer of cermet materials. The heat treated discs had the same dimensions of the coated ones. The tested specimens have been machined from the real braking components, the pins have been extracted from the brake pads while the discs from the braking tracks of the rotors. Since the novelty of the application of the HVOF coatings in the field of braking systems, two preliminary studies of the surface parameters of the coated discs and of the running-in of the pin-disc system have been performed. The first one was conducted on WC-CoCr coated discs polished with different intensities in order to achieve four different average surface roughnesses: 5, 1, 0.1, 0.04 µm respectively. The results of the study highlighted that the wear of the friction material decreased by four order of magnitude by passing from an average surface roughness equal to 5 µm to 0.04 µm. The friction coefficient followed the opposite trend passing from 0.3 for the 5 µm rough coating to 0.7 for the 0.04 µm. The SEM observation of the wear tracks on the discs revealed a high material transfer from the pins in the case of the 5 µm rough coatings due to the abrasive interaction exerted by the hard coating asperities on the relatively soft friction material. The compactness of the material transferred onto the disc surface increased as the average surface roughness of the coating decreased leading to the formation of contact patches also on the coated disc surfaces. From the profilometric analysis of the worn disc their wear resulted negligible. The EDXS analysis of the secondary plateaus of pins detected an increasingly concentration of tungsten and cobalt with the decrease in the surface roughness of the coating meaning that, although the wear of the coating could not be detected from the profilometer, some minor transfer of material occurred during the sliding action. From all the considerations mentioned above the most promising surface roughness, in terms of frictional performances and industrial feasibility, was equal to 1 µm. The second study aimed at the investigation of the running-in stage of the WC-CoCr and Cr3C2-NiCr coated discs in the as-sprayed (Ra ≈ 5 µm) and polished conditions (Ra ≈ 1 µm). From this former investigation the polishing procedure of the coated discs was found fundamental in order to reach the best frictional and wear performances; the spontaneous surface modifications occurring during pin-on-disc tests were not as efficient as the controlled polishing procedure in reducing the surface parameters of the coated discs and so in improving their performances. On the basis of the results of the two former studies presented above, the tribological characterization at both room and high temperature (300°C) of the WC-CoCr, Cr3C2-NiCr, WC-Cr3C2-CoCr, WC-FeCrAlY coated discs and of the heat treated one was performed on specimens with an average surface roughness at around 1 µm. Three different friction material formulations were used in order to optimize their frictional and wear performances with the disc counterface. In all cases the EDXS analysis detected the presence of the coating elements, i.e. tungsten, cobalt and nickel, inside the secondary plateaus of the friction material. Depending on the abrasive content of the friction materials and on the testing temperature the amount of the transferred elements varied, i.e. a low amount of abrasives and a high testing temperature gave rise to a reduction in the elements transferred on the pin surfaces. The best tribological combination was the coupling between the friction material FMB, i.e. the one with the lowest amount of abrasives, and the WC-FeCrAlY coated disc. The results attained with the pin-on-disc tribological characterization of the friction materials were validated during full-scale dyno bench tests. These tests were performed on the most promising materials and they had a twofold aim: as mentioned above they were used to validate the results of the tribometer tests and to collect the particulate matter emitted during braking. The analysis of the wear debris highlighted that, in the case of the friction material FM4 slid against the WC-CoCr coated disc, some cobalt was present. From the deeper analysis of the debris resulted that traces of tungsten and cobalt were found only in the coarser fraction of wear debris, collected on the PM1 filter. The coupled SEM+EDXS analysis of the finer particulate matter, with an average aerodynamic diameter varying from 0.25 to 0.054 µm, did not detected the presence of the coating elements. This was consistent with the observations of the PM1 wear debris that identified WC particles with dimensions comparable to that of the initial carbide particle size inside the coatings; the wear mechanism of the coatings seemed to be the carbide pullout from the metallic matrix without the further fragmentation of the particles due to sliding. Nevertheless, during one of the TEM observation of the particles with an average aerodynamic diameter of 0.094 µm the SAED analysis detected the presence of W2C. On the basis of this last observation and considering that the presence of cobalt inside the finest fraction of debris could not be completely disregarded since it could remain stuck on the W2C particles, the selected coating material for the application in braking systems was the WC-FeCrAlY. This conclusion was consistent with the frictional and wear data attained from the PoD tribological characterization that identified the FMB friction material and the WC-FeCrAlY coated discs as the best coupling in terms of frictional and wear behavior. The study of the thermal behavior of the novel developed braking materials during a pin-on-disc room temperature test was performed by means of a finite element simulation based on the perfect contact approach. The heat flux applied as the thermal input of the model was calculated from the experimental data acquired during the tests. The calibration of the boundary conditions was performed by comparing the experimental curves of the temperatures acquired during the tests with the temperature curves calculated from the FE analysis. The results of the simulations showed that the temperature field during the pin-on-disc tests was influenced from both the friction coefficient and from the thermal properties of the coated discs, i.e. the lower thermal conductivity of the coatings gave rise to a higher average contact temperature with respect the uncoated cast iron discs. The results of FE analysis were then used to propose an analytical relationship that could be used for describing the raise in temperature during a pin-on-disc test without performing further thermal simulations.

The implantation of stents is an effective procedure to unblock the arteries of patients with serious heart problems. Traditionally, stents are made of inert materials such as stainless steel and titanium alloys. It has been shown that the traditional stents can cause restenosis or thrombosis. In recent years the proposal of biodegradable stents is attracting the interest of the industry and the research, since the stent is mechanically needed only in the first year, eliminating the problems caused by the long duration of the implant. Magnesium (Mg) alloys are of increasing interest because of their engineering properties, including the high strength to density ratio. Recently, they have been also proposed as biomaterials for the production of bioabsorbable stents and for other medical devices due to its harmless effect to human body when compared with other structural materials. In this work, the possibility to produce biodegradable stents made of magnesium starting from the powder is investigated. Pure Mg and the AZ91 Mg powders were used in the present study. Pure Mg powder was sintered by Spark Plasma Sintering at 400 and 470 °C, and the AZ91 powder was sintered at 400 °C without homogenization and at 470 °C after homogenization. The preforms produced by sintering were then submitted to hot compression, rod extrusion and tube extrusion at 330 and 380 °C with different strain rates. During all the process was not possible to obtain recrystallization or grain refinement on pure Mg, and after the tube extrusion it has shown a high brittleness and sever defects, which led to the decision of proceed only with AZ91 alloy. The AZ91 presented good recrystallization in al process, always following the Zener-Hollomon relation. The grain size obtained was as small as 1.5 μm. The AZ91 tube was then submitted to manual machining and laser cutting and it was possible to obtain the stent precursors. The results of the present investigation have demonstrated the suitability of the proposed route for producing Mg-based stents. It is clear, however, that the process has to be further optimized, investigating also the possibility of using different types of powder with a tailored composition.

In the present work, micro-tubular solid oxide fuel cells μt-SOFCs) constituted by NiO/YSZ anode with an embedded current collector, YSZ as electrolyte, YSZ/LSM as functional cathode layer and pure LSM as cathode current collector layer were fabricated by dip-coating technique. The fuel cell was designed according to the anode-supported configuration with a metallic coil introduced within the anode during the cell fabrication. The production of the devices through wet colloidal process required the optimization of suspensions employed for the dip-coating. Then, investigation on rheological properties for the anode and electrolyte water-base slurries was carried out with particular emphasis to the solid loading and the concentration of slurry additives as well as temperature. In addition, thermal analyses elucidated the response of anode, electrolyte and cathode layers during drying, binder burn-out and sintering processes. The thermal behaviour of pyrolisable materials and oxidation of the metal components used as current collector was performed using conditions identical to cell fabrication like temperatures as high as 1400°C in oxidative atmosphere. After sintering, the complete μt-SOFCs with embedded current collector were produced with outer diameter as low as 1.0 mm and length of 30 mm with an effective active cathode length of 20 mm resulting in an active area of 0.63 cm2. The cell performance was analyzed by V-j plots in the temperature range of 700-800°C where the effect of the cell diameter and current collector characteristics on power density was pointed out. The efficiency of current collector was examined by comparing coils with different configurations (turns per unit length) as well as nature of the metal. The cell performance was demonstrated to be related to the current collector configuration. In particular, as twice the turns per unit length are as double the current density is, thus making the power density 4-fold. An additional improvement of the cell performance was found for the palladium current collector where the power density was increased by a factor more than 4 in comparison with the cell made with nickel collector due to the higher catalytic activity of palladium for electrochemical reactions. On the basis of these findings, a further development of μt-SOFCs with embedded collector was suggested with an alternative design of palladium current collector for which an estimate of power density of micro-tubular cell provided values higher than 0.7 W/cm2 at temperature of 800°C.

Surface porous silicon based ceramics are a class of materials with excellent mechanical, physical and chemical properties and for this reason they are widely used in different fields of application. The resultant properties of these material are due principally to the combination of the chemical composition (coordination with the Si atom) and the specific geometry of the pattern. These parameters are able to influence phenomena such as the biological activity, the exposed surface area and the thermal, mechanical and chemical resistance. Techniques used nowadays to synthesize these ceramics with a specific patter are usually really complicated, expensive and time-consuming with limitations for the large-scale industrial application. The Breath Figure method is a new fast and highly controllable technique that allows to decorate the surface of polymer films with different porous patterns. A large variety of starting materials can be used to perform this process, obtaining porous films with different characteristics and with a specific control on the entire process. In this work we used a UV cross-linkable polysiloxane as precursor for the Breath Figure process in order to combine the pattern procedure with the polymer derived ceramic method. Initially, the effects of the process variables on the final surface porosity was evaluated, identifying the parameters which most influence the final material. After the patterning, materials with different characteristics were pyrolyzed under different atmospheres in order to induce simultaneously the ceramic conversion and the chemical modification of the silicone structure. Three different porous silicon-based ceramics were obtained using flowing air, nitrogen and ammonia during the heat treatments, respectively: silicon dioxide, silicon oxycarbide and silicon oxynitride. All these material have been proposed as implant coating for different body districts, but recent studies demonstrated the potential application of silicon oxynitrides as bone implant coatings due to the enhanced bioactivity and osteoinductivity of the ceramic. For this reason in the second part of this work we evaluated the potential bioactivity of surface porous silicon oxynitrides in terms of bioactive silicon ions release capability and effects of different porosity degrees on cells behavior. Four different surface pattern were applied on titanium alloy disks and used for an in vitro characterization using human Mesenchymal Stem Cells and compared with uncoated titanium. The results indicated that the silicon ions release from the coating surface leads to an increase of the cellular activity with the porous pattern influencing the hMSC initial adhesion and proliferation.