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A hydroxyapatite–Fe2O3 based material of natural origin as an active sunscreen filter

Publication . Piccirillo, C.; Rocha, C.; Tobaldi, D. M.; Pullar, R. C.; Labrincha, J. A.; Ferreira, M. O.; Castro, Paula M. L.; Pintado, M. E.

The use of sunscreens as protective barriers against skin damage and cancer, by absorbing harmful UVA and UVB rays, is becoming an increasingly important issue. Such products are usually based on TiO2 or ZnO, although both Fe2O3 and hydroxyapatite (Ca10(PO4)6(OH)2, HAp) doped with metal ions have been reported as being ultraviolet (UV) absorbing materials. HAp is the main component of bone; it is, therefore, highly biocompatible. In the present work, an iron-doped HAp-based material, containing both Fe ions substituted into the HAp structure and iron oxide in hematite (a-Fe2O3) form, was successfully developed from waste cod fish bones. This was achieved through a simple process of treating the bones in a Fe(II) containing solution, followed by heating at 700 C. The material showed good absorption in the whole UV range and did not form radicals when irradiated. The sunscreen cream formulated with this material could be used as a broad sunscreen protector (lcrit > 370 nm), showing high absorption both in the UVA and UVB ranges. Because of its absorption properties it would be classified as 5 star protection according to the Boots UVA star rating system. The cream is also photostable, and does not cause irritation or erythema formation when in contact with the human skin. These results show that a food by-product such as fish bones could be converted into a valuable product, with potential applications in health care and cosmetics. This is the first time a HAp-based sunscreen cream has been developed and validated as a proof of concept.

2014Journal article

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Hydroxyapatite-based materials of marine origin: a bioactivity and sintering study

Publication . Piccirillo, C.; Pullar, R. C.; Costa, E.; Santos-Silva, A.; Pintado, Manuela; Castro, Paula M. L.

Single phase hydroxyapatite (HAp) and biphasic material hydroxyapatite/beta-tricalcium phosphate (HAp/beta-TCP) were obtained from a marine source (Atlantic cod fish bones). Here we report a study on the biological properties of these materials, including cytotoxicity, bioactivity and haemocompatibility. Results showed that the materials are not cytotoxic, neither in their powder nor in pellet form; indeed growth of Saos-2 cells was comparable to that of commercial. The haemolysis rate was lower than 2%; hence the materials can be classified as non-haemolytic. Moreover, when immersed in Simulated Body Fluid (SBF), crystal formation was observed on the surface of both materials. The sintering behaviour of the samples was also studied; both powders showed very high sinterability (density higher than 95% of the theoretical value). Overall, these results confirm the suitability of these materials for biomedical applications.

2015Journal article

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Hydroxyapatite and chloroapatite derived from sardine by-products

Publication . Piccirillo, C.; Pullar, R. C.; Tobaldi, D. M.; Castro, Paula M. L.; Pintado, M. E.

In this paper, phosphate-based compounds used in biomedicine were extracted from bones and scales of European sardines (Sardina pilchardus); this is the first time that different parts of the same fish are used for the extraction of these kinds of materials. The bones and scales behave very differently with processing, producing different materials when annealed between 600 and 1000 °C. The bones formed a mixture of hydroxyapatite (Ca10(PO4)6(OH)2, HAp) and β-tri-calcium phosphate (β-Ca3(PO4)2, β-TCP), with a higher content of β-TCP obtained with increasing temperature. This bi-phasic material has a high added value, as it is employed as a bioceramic; in fact HAp has good biocompatibility while β-TCP has better resorbability than HAp, despite being less biocompatible. With scales, on the other hand, either a HAp-based material or a chlorine-substitute HAp containing material (chloroapatite (Ca10(PO4)6Cl2, ClAp) were produced. HAp-based material was obtained with a simple annealing process; for ClAp, on the other hand, a combined washing–annealing process was used. ClAp is also used in biomedicine, due to its improved resorption, mechanical properties and bioactivity. This is the first time ClAp of marine origin was produced.

2014Journal article

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Nuclear magnetic resonance metabolomics of iron deficiency in soybean leaves

Publication . Lima, Marta R. M.; Diaz, Sílvia O.; Lamego, Inês; Grusak, Michael A.; Vasconcelos, Marta; Gil, Ana M.

Iron (Fe) deficiency is an important agricultural concern that leads to lower yields and crop quality. A better understanding of the condition at the metabolome level could contribute to the design of strategies to ameliorate Fe-deficiency problems. Fe-sufficient and Fe-deficient soybean leaf extracts and whole leaves were analyzed by liquid 1H nuclear magnetic resonance (NMR) and high-resolution magic-angle spinning NMR spectroscopy, respectively. Overall, 30 compounds were measurable and identifiable (comprising amino and organic acids, fatty acids, carbohydrates, alcohols, polyphenols, and others), along with 22 additional spin systems (still unassigned). Thus, metabolite differences between treatment conditions could be evaluated for different compound families simultaneously. Statistically relevant metabolite changes upon Fe deficiency included higher levels of alanine, asparagine/aspartate, threonine, valine, GABA, acetate, choline, ethanolamine, hypoxanthine, trigonelline, and polyphenols and lower levels of citrate, malate, ethanol, methanol, chlorogenate, and 3-methyl-2-oxovalerate. The data indicate that the main metabolic impacts of Fe deficiency in soybean include enhanced tricarboxylic acid cycle activity, enhanced activation of oxidative stress protection mechanisms and enhanced amino acid accumulation. Metabolites showing accumulation differences in Fe-starved but visually asymptomatic leaves could serve as biomarkers for early detection of Fe-deficiency stress.

2014Journal article

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