Biomineralization: A new tool for developing eco-sustainable Ti-doped hydroxyapatite-based hybrid UV filters.

It is well known that the prolonged exposure to UV radiation from sunlight can compromise human health and is particularly damaging to the skin, leading to sunburn, photo-aging and skin cancer. Sunscreen formulations containing UV-filters present a barrier against solar UV and help to mitigate the harmful effects however, concern about their safety for both human and environmental health is still a much-debated topic. EC regulations classify UV-filters depending on their chemical nature, particle size, and mechanism of action. Furthermore, it regulates their use in cosmetic products with specific limitations in terms of concentration (organic UV filters) and particle size and surface modification to reduce their photo-activity (mineral UV filters). The regulations have prompted researchers to identify new materials that show promise for use in sunscreens. In this work, biomimetic hybrid materials composed of titanium-doped hydroxyapatite (TiHA) grown on two different organic templates, derived from animal (gelatin - from pig skin) and vegetable (alginate - from algae) sources. These novel materials were developed and characterized to obtain sustainable UV-filters as a safer alternative for both human and ecosystem health. This 'biomineralization' process yielded TiHA nanoparticles that demonstrated high UV reflectance, low photoactivity, good biocompatibility and an aggregate morphology which prevents dermal penetration. The materials are safe for topical application and for the marine environment; moreover, they can protect organic sunscreen components from photodegradation and yield long-lasting protection.

Surface properties modulate protein corona formation and determine cellular uptake and cytotoxicity of silver nanoparticles.

Nanoparticles (NPs) have been studied for biomedical applications, ranging from prevention, diagnosis and treatment of diseases. However, the lack of the basic understanding of how NPs interact with the biological environment has severely limited their delivery efficiency to the target tissue and clinical translation. Here, we show the effective regulation of the surface properties of NPs, by controlling the surface ligand density, and their effect on serum protein adsorption, cellular uptake and cytotoxicity. The surface properties of NPs are tuned through the controlled replacement of native ligands, which favor protein adsorption, with ligands capable of increasing protein adsorption resistance. The extent and composition of the protein layer adsorbed on NPs are strongly correlated to the degree of ligands replaced on their surface and, while BSA is the most abundant protein detected, ApoE is the one whose amount is most affected by surface properties. On increasing the protein resistance, cellular uptake and cytotoxicity in mouse embryonic fibroblasts of NPs are drastically reduced, but the surface coating has no effect on the process by which NPs mainly induce cell death. Overall, this study reveals that the tuning of the surface properties of NPs allows us to regulate their biological outcomes by controlling their ability to adsorb serum proteins.

Luminescent protein staining with Re(i) tetrazolato complexes.

Within the general framework of our past and current studies dealing with the investigation of the photophysical properties and the biological behavior of the family of tetrazolato and tetrazole Re(i) complexes, we have endeavored to investigate their potential in the luminescent staining of proteins purified by acrylamide gel electrophoresis. With the aim to provide the first examples of luminescent Re(i) complexes to be exploited for this specific purpose, we have designed and prepared four new Re(i)-based species with the general formula fac-[Re(CO)3(N^N)(Tph)]2-/0, where Tph is the 5-(phenyl)tetrazolato anion and N^N is in turn represented by bathophenanthroline disulfonate (BPS), bathocuproine disulfonate (BCS) or by the SO3- free bathocuproine (BC). In this latter case, the neutral complex fac-[Re(CO)3(BC)(Tph)] served as a model species for the characterization of the former disulfonate complexes. Its cationic analogue fac-[Re(CO)3(BC)(Tph-Me)]+ was also prepared by a straightforward methylation reaction. All complexes displayed bright phosphorescence in organic media and, relative to their water solubility, the dianionic species fac-[Re(CO)3(BPS)(Tph)]2- and fac-[Re(CO)3(BCS)(Tph)]2- were also highly emissive in aqueous solution. The sulfonate groups played a key role in promoting and significantly enhancing the luminescent staining performances of both the Re(i) complexes fac-[Re(CO)3(BPS)(Tph)]2- and fac-[Re(CO)3(BCS)(Tph)]2- for proteins. Highlighting a response superior to that of Coomassie Blue and comparable to the one obtained by the well-known silver staining method, these dianionic Re(i)-complexes could efficiently detect up to 50 ng of pure Bovine Serum Albumin (BSA), as well as all proteins found in a Standard Protein Marker mix and from a total protein extract. A lower but still good response for luminescent protein staining was surprisingly obtained by employing the -SO3- free neutral and cationic complexes fac-[Re(CO)3(BC)(Tph)] and fac-[Re(CO)3(BC)(Tph-Me)]+, respectively. These preliminary results open up new possibilities for the further widening of the use of Re(i)-based complexes as luminescent protein staining agents.