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Amorphous calcium phosphate (ACP) is a material of high interest for dentistry, orthopedics, and other biomedical sectors. Being intrinsically metastable, the process of transformation of ACP into a crystalline phase upon heating is of high relevance for the development of innovative bioceramics. Here we have first studied the thermal behavior of a citrate-stabilized ACP (Cit-ACP) also doped with fluoride ions (Cit-FACP) prepared at three different nominal Cit/Ca ratios (i.e.4, 2, 1) by differential thermal analysis. Next, the physico-chemical features of the crystalline products as well as thein vitrocell response to the materials were investigated. A citrate and fluoride free ACP sample was also tested as the blank. We have found that the activation energy of crystallization of Cit-(F)ACP samples is lower in comparison to the blank ACP and this is influenced by the nominal Cit/Ca molar ratio. Interestingly, we have discovered that the thermal treatment of Cit-(F)ACP at 800 °C yields hydroxyapatite (HA) or fluorapatite (FHA) as the main products differently from blank ACP that, like most of the ACPs reported in the literature, yields ?-tricalcium phosphate. This was attributed to the Ca/P ratio of Cit-(F)ACP, which is similar to HA. A study of the crystalline products has revealed that all the (F)HA samples were non-cytotoxic, and retained carbonate ions in the crystal structure despite the heat treatment that should have induced decarbonation. The morphology of the products is influenced by the nominal Cit/Ca ratio and the presence of fluoride, ranging from spherical nanoparticles to micrometric hexagonal rods. Overall, our results prove that the thermal crystallization of Cit-(F)ACP is markedly different from classic ACP based materials and the thermal treatment of Cit-(F)ACP represents an attractive route for producing pure bioactive HA ceramics.

Materials science researchers and engineers are exploring the complex domain of biomaterials, as it requires consideration of biocompatibility and, in the frame of Regenerative Medicine, assessment on bioactivity, bio-reabsorbability and ability to be integrated and remodeled. Such a research field requires interdisciplinary approaches and robust knowledge of chemistry, biology and mechanics, in order to cope with the complex chemical composition, multiscale structure and biological functions of the organ to be replaced/regenerated. In fact, after decades of attempts to develop biomaterials able to effectively regenerate tissues/organs, most of them failed in their task and today the need of a radically new approach is commonly recognized. In this scenario, the article describes new frontiers in biomaterial development, fed by novel nature-inspired approaches, and able to circumvent the limitations of the current ceramic technology. Thus it will be illustrated how the biomineralization process, by which nature builds innumerable biologic structures, could be used to obtain scaffolds for regeneration of bone and also complex anatomical regions such as the osteochondral and periodontal tissues. Then the article will show recent developments for load-bearing scaffolds fabrication by using a revolutionary biomorphic transformation process, able to convert a natural hierarchically organized structure in fully ceramic and bioactive devices retaining the original 3-D multiscale structure and the unique damage tolerant performance. Finally, it will be shown how such new bio-devices can be powered by functionalization with magnetic doping and/or nanoparticles, to obtain on-demand activation of bio-functionalities. Particularly, the recent development of a biocompatible, bioactive superparamagnetic apatite is described, as a tool very promising to apply novel safer therapies in nanomedicine and to boost the endogenous potential of debilitated patients.

The present work describes biomimetic hybrid microspheres made of collagen type I-like peptide matrix (RCP) mineralised with Fe2+/Fe3+ doping hydroxyapatite (RCPFeHA) by a bio-inspired process. Superparamagnetic RCPFeHA microspheres are obtained by emulsification of the hybrid slurries in the presence of citrate ions, to achieve a biomimetic surface functionalization improving the bioactivity and the dispersion ability in cell culture medium. A biological in vitro study correlates the osteoblast cells behaviour to calcium and iron ions released by the hybrid microspheres in culture media mimicking physiological or inflammatory environment, evidencing a clear triggering of cell activity and bio-resorption ability. In presence of the microspheres, the osteoblast cells maintain their typical morphology and no cell damage was detected, whereas also showing up- regulation of osteogenic markers. The ability of the hybrid microspheres to undergo bio-resorption and release bioactive ions in response to different environmental stimuli without harmful effects opens new perspectives in bone regeneration, as magnetically active bone substitute with potential ability of drug carrier and smart response in the presence of inflammatory states.

First results of an innovative multi-proxy approach applied to glacier-related trees for assessing climatic and substrate influence on tree rings and needle VOCs are reported. Tree-ring stable isotopes, tree-ring growth patterns and needle volatile organic compounds where analysed at two Larix decidua Mill. sites in five trees of similar size growing in close areas mainly differentiated by the contrasting geomorphological features: the debriscovered Miage Glacier ("Glacier") and a lateral moraine ("Control"). Over the period 2003-2012, tree rings at the Glacier site showed more enriched 13C mean values (p

Scientific research on bone and osteochondral tissue regeneration is increasingly becoming the most promising response to a number of disabling pathologies with huge impact on the progressively growing and aging world population. The biomimicry of scaffolds with the target tissue is now universally considered to be a key requirement to properly instruct cells toward the restoration of specific physiological functioning. In this respect, this chapter presents an overview of recent findings on hydroxyapatite, biomimetic materials, and devices addressed to bone and osteochondral tissue regeneration. Particular focus is given to the novel biomimetic hydroxyapatite phases, including the newly discovered superparamagnetic hydroxyapatite nanoparticles and to the biomineralization process to develop bioinspired hybrid inorganic-polymeric porous scaffolds even endowed with magnetic features. Finally, the technology to transform ligneous sources into hierarchically organized biomorphic hydroxyapatite-based porous scaffolds that may provide novel and more effective solutions to assist the regeneration of long segmental bones was described.

Materials science is today experiencing a paradigmatic change in the development of new smart devices for biomedical applications. Indeed there is a strong demand for new solutions able to face and solve degenerative and highly invalidating diseases that involve a steadily increasing number of people, also due to the progressive ageing of the population. In particular, the regeneration of hard tissues (i.e. bone, cartilage, tooth) is one of the most demanding issues in medicine and requires smart devices showing high mimicry of the host tissues and able to instruct and address progenitor cells to the regeneration of new functional tissue. This chapter highlights the emerging concepts of bio-inspiration, by which natural processes can be reproduced in lab and addressed to the synthesisof scaffolds mimicking complex multi-functional tissues. Besides, nanobiomagnetism is presented as a new strategy to develop on demand bio-devices that can be activated and controlled by noninvasive remote signaling. These new concepts promise to be one of the most relevant drivers for the development of new generation smart biomedical devices with high regenerative performance in the next decade.

Objective. To determine the effect of laser irradiation at a low dose on human osteoblast- like cells. Materials and methods. 32 porous hydroxyapatite scaffolds currently used for bone tissue engineering were seeded with MG63 cells and irradiated or not with a GaAlAs diode laser (wavelength 915 nm, dose 2 J/cm2) using different power density and exposure duration. Results. After 72-h incubation, cells showed well spread morphology and good adhesion on both laser-treated and untreated scaffolds. Laser irradiation did not interfere in cell viability and proliferation as compared with the non-irradiated controls. Conclusion. This study suggests that there is no effect of 915 nm laser irradiation at a dose of 2 J/cm2 on the proliferation rate of MG63 cells. Future investigations are needed to compare different dose and wavelength regimens in order to determine the optimal set of laser parameters for maximum cell yield and safe clinical application.

Lactoferrin (LF) is a bioactive glycoprotein that became recently interesting in the field of bone regeneration for its modulatory effect on bone cells. On the basis of this evidence this work aims to functionalize biomimetic hydroxyapatite (HA) nanocrystals with LF to study their effect on osteogenic differentiation of mesenchymal stem cells (MSCs). The orientation of LF on the HA surface was analyzed by spectroscopic and thermal techniques. Three samples with different amounts of LF attached to HA nanocrystals were tested in vitro. The combined effect of HA and LF on MSC proliferation and morphology, alkaline phosphatase (ALP) activity, and gene expression were evaluated at different time points. The sample with the lowest LF amount showed the best bioactivity probably due to the formation of a single layer of protein with a better molecular orientation. Coupling of HA-LF did not affect cell proliferation and morphology, while analysis of HA-LF on ALP activity and messenger RNA expression of the selected genes, demonstrated the role of HA-LF in the induction of osteogenic markers. HA-LF represents a promising system to be used to manufacture bioactive functional materials in tissue engineering (as scaffolds, injectable cements, or coatings for metallic implants) with enhanced anabolic activity to treat bone diseases.