International Materials Reviews

Engineering biomaterials for regenerative medicine involves a myriad of aspects to be considered for the successful design, interaction with cells and integration with living tissues (i.e. pore size, mechanical properties, degradation rate, biological activity). Among different technologies used to functionalise synthetic biomaterials and promote cell adhesion, cell growth and cell differentiation, this review focuses on strategies to organise extracellular matrix (ECM) proteins in a biomimetic way, as cells do in natural tissues in vivo (the ECM is a mesh of proteins that surrounds cells, and therefore, constitutes the scaffolding of a tissue), but using functional materials instead of living cells. The authors critically review material-based strategies to organise fibronectin (FN), a core component in the ECM of many tissues, and engineer microenvironments that recapitulate the structure and properties of the ECM. Material-driven organisation of FN in analogy with their natural cell-mediated assembly is a powerful route to engineer the network structure and biological activity of FN fibrillar matrices, seeking to develop biomimetic scaffolds for regenerative medicine. Here, the authors discuss different routes to promote the cell-free formation of FN fibrils as well as the biological impact of these engineered cellular microenvironments.

It was discovered over 75 years ago that minor additions of elements with high affinity to oxygen exert a profound effect on oxidation resistance of many metals and alloys. In this report, progress in understanding the ‘reactive element effect’ (REE) and opportunities created for controlling the high-temperature oxidation of magnesium alloys were reviewed. Magnesium, the lightest structural metal, exhibits high affinity to oxygen and, as opposed to heat-resistant materials, does not form a dense, slow-growing and protective oxide layer. However, additions of small amounts of reactive elements (REs) to magnesium alloys produce a number of positive effects in improving their oxidation resistance. What is of crucial importance for magnesium is that RE benefits are also extended to its ignition, flammability, evaporation and liquid-state reactivity. The mechanism by which these elements influence oxidation and other related behaviour remains, so far, unclear. Although no specific theory explaining the REE on magnesium has been developed, growth kinetics, surface morphology and internal microstructure of magnesia films and scales, doped with REs show characteristics typical for high-temperature materials that form protective oxides.