Browsing by Author "Tobaldi, David M."
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- Calcium phosphate-based materials of natural origin showing photocatalytic activityPublication . Piccirillo, Clara; Dunnill, Charles W.; Pullar, Robert C.; Tobaldi, David M.; Labrincha, João A.; Parkin, Ivan P.; Pintado, Manuela M.; Castro, Paula M. L.Calcium phosphate based materials of natural origin with photocatalytic properties were produced. Bones of Atlantic cod fish were treated in appropriate solutions (either Ca- or Ti-containing salts) and successively annealed. Results showed multiphasic materials (hydroxyapatite, beta-tricalcium phosphate and anatase titania) with excellent photocatalytic performance under both UV and visible light, with an anatase concentration of only about 2 mol%. Results with such a low amount of anatase have never been reported before for a calcium phosphate-based material; this is attributed to the presence of anatase being mainly on the surface. Single-phase hydroxyapatite (Ca-10(PO4)(6)(OH)(2) or HAp) also showed some photocatalytic properties and antibacterial activity.
- Films of chitosan and natural modified hydroxyapatite as effective UV-protecting, biocompatible and antibacterial wound dressingsPublication . Cunha, Carla S.; Castro, Pedro J.; Sousa, Sérgio C.; Pullar, Robert C.; Tobaldi, David M.; Piccirillo, Clara; Pintado, Maria M.Chitosan is a natural polysaccharide widely used in biomedicine, for instance for wound dressing. Hydroxyapatite is a very bioactive calcium phosphate which, if modified with an appropriate element (iron Fe), can also have UV-absorbing properties. In this work, we report the study of films of chitosan incorporated with iron-modified hydroxyapatite of natural origin (from cod fish bones); this combination led to an innovative chitosan-based material with excellent and advanced functional properties. The films showed very high UV absorption (Ultraviolet Protection Factor (UPF) value higher than 50). This is the first time that a chitosan-based material has shown such high UV protection properties. The films also showed to be non-cytotoxic, and possessed antimicrobial activity towards both Gram-positive and negative strains. Their mechanical properties, optimised with an experimental design approach, confirmed their potential use as multifunctional wound dressing, capable of reducing bacterial infections and, at the same time, protecting from UV light.
- Increased UV absorption properties of natural hydroxyapatite-based sunscreen through laser ablation modification in liquidPublication . Piccirillo, Clara; Fernández‐Arias, Mónica; Boutinguiza, Mohamed; Tobaldi, David M.; Del Val, Jesus; Pintado, Maria M.; Pou, JuanSunfilters based on hydroxyapatite (HAp) and iron‐containing compounds (Fe2O3 and calcium iron phosphates) are of increasing interest, as they show UV absorption without generating health endanger free radicals (usually observed when other inorganic sunscreens are used). In this paper, laser ablation of solids in liquids has been applied to improve the UV absorption properties of a HAp based Fe‐containing sunscreen powder derived from cod fish bones. Two different laser wavelengths were explored (532 and 1064 nm, green and infrared, respectively); an improved experimental device was used, to allow a fine control of the volume of the irradiated particles. Results show an increased UV absorbance for the laser‐treated powders in comparison with the untreated ones; this can be explained considering the smaller particle size and increased surface area; the higher iron concentration in the powders may also be determinant. Enhanced absorption was also observed in the near‐infrared range, making the powders even more suitable for sunscreen applications. The green laser was more effective than the infrared one. Overall, laser ablation showed to be a powerful technique to control the size of the sunscreen particles and tailor their optical properties.
- Luminescent calcium phosphate bioceramics doped with europium derived from fish industry byproductsPublication . Piccirillo, Clara; Adamiano, Alessio; Tobaldi, David M.; Montalti, Marco; Manzi, Jeannette; Castro, P. M. Lima; Panseri, Silvia; Montesi, Monica; Sprio, Simone; Tampieri, Anna; Iafisco, MicheleThe recovery of valuable compounds from byproducts is at present a priority topic for social, environmental, and economic reasons. In this work we report for the first time the preparation of luminescent calcium phosphate (CaP) bioceramics from waste codfish bones. Codfish bones were treated in aqueous Eu(NO 3 ) 3 solu- tions of different concentrations, followed by thermal treatment at either 700°Cor 1100°C. The resulting materials consisted of hydroxyapatite (HAp), b-tricalcium phosphate (b-TCP) and a small amount of Eu 2 O 3 . Chemical and structural charac- terization showed that the Eu ions were successfully introduced into the bones and, hence, in the thermally treated CaP phases obtained from them, although mainly in the b-TCP lattice. Photol uminescence investigatio n revealed that all the materials are luminescent, with samples treated at 1100°C having more intense luminescence than those prepared at 700°C. In vitro evaluation of cell-materials interaction indicated that all the samples displayed good cytocompatibility toward osteoblast cells. This work demonstrates that a simple and effective process, employing Eu as a dopant, can convert fish industry byproducts into highly valu- able luminescent CaP bioceramics, having potential applications in biology and medicine for bio-imaging
- A sustainable replacement for TiO2 in photocatalyst construction materials: Hydroxyapatite-based photocatalytic additives, made from the valorisation of food wastes of marine originPublication . Saeli, Manfredi; Piccirillo, Clara; Tobaldi, David M.; Binions, Russell; Castro, Paula M. L.; Pullar, Robert C.The use of waste materials and by-products in building materials is of increasing importance to improve sustainability in construction, as is the incorporation of photocatalytic materials to both combat atmospheric pollution and protect the structures and façades. This work reports the innovative use of photocatalytic hydroxyapatite (HAp) based powders, derived from Atlantic codfish bone wastes, as an additive to natural hydraulic lime mortars. HAp is the main component of bone, and hence is non-toxic and biocompatible. This is the first time that such a calcium phosphate-based photocatalyst, or indeed any fish/marine derived wastes, have been added to building materials. A key factor is that this HApbased photocatalyst contains only 1 wt% TiO2, the material usually used as a photocatalyst in construction materials. As we only add 1e5 wt% of our total HAp-based material to the mortar, this means our photocatalytic mortars only contain 0.01e0.05 wt% titania (100e500 ppm), two orders of magnitude less than the quantities of 2e10 wt% TiO2 which are usually needed. Our photocatalyst is made from a sustainable waste stream by simple solution and thermal processing, and thus with a much smaller impact on the environment. Specimens were made by either traditional intermixing techniques, or by a post-curing coating procedure. All showed gas-phase photocatalytic activity for abatement of NOx pollutants under solar light. With intermixing, NOx abatement of 6.3e8.3% was observed. However, for coated mortars, superior NOx conversion rates were achieved of 7.1% and 23.8%, with 1 and 5 wt% additions, respectively. These results show the potential of this naturally-derived photocatalyst for applications in the construction industry, leading to lower atmospheric pollution and the creation of more durable/lower maintenance building façades, and environmentally sustainable materials for the preservation of cultural heritage.