Biogenic Inorganic Polysilicates (Biosilica): Formation and Biomedical Applications

Coding cell micropatterns through peptide inkjet printing for arbitrary biomineralized architectures

Well-designed micropatterns present in native tissues and organs involve changes in extracellular matrix compositions, cell types and mechanical properties to reflect complex biological functions. However, the design and fabrication of these micropatterns in vitro to meet task-specific biomedical applications remains a challenge. A de novo design strategy to code and synthesize functional micropatterns is presented to engineer cell alignment through the integration of aqueous-peptide inkjet printing and site-specific biomineralization. The inkjet printing provides direct writing of macroscopic biosilica selective peptide-R5 patterns with micrometer-scale resolution on the surface of a biopolymer (silk) hydrogel. This is combined with in situ biomineralization of the R5 peptide for site-specific growth of silica nanoparticles on the micropatterns, avoiding the use of harsh chemicals or complex processing. The functional micropatterned systems are used to align human mesenchymal stem cells and bovine serum albumin. This combination of peptide printing and site-specific biomineralization provides a new route for developing cost-effective micropatterns, with implications for broader materials designs. Coding cell micropatterns through peptide inkjet printing for arbitrary biomineralized architectures is demonstrated here. The functional micropatterned systems are used to align human mesenchymal stem cells and bovine serum albumin in vitro, avoiding the use of harsh chemicals or complex processing, while providing potential applications in developing cost-effective micropatterns to meet task-specific biomedical applications.

Hierarchical architecture of sponge spicules: biocatalytic and structure-directing activity of silicatein proteins as model for bioinspired applications

Since the first description of the silicateins, a group of enzymes that mediate the formation of the amorphous, hydrated biosilica of the skeleton of the siliceous sponges, much progress has been achieved in the understanding of this biomineralization process. These discoveries include, beside the proof of the enzymatic nature of the sponge biosilica formation, the dual property of the enzyme, to act both as a structure-forming and structure-guiding protein, and the demonstration that the initial product of silicatein is a soft, gel-like material that has to undergo a maturation process during which it achieves its favorable physical-chemical properties allowing the development of various technological or medical applications. This process comprises the hardening of the material by the removal of water and ions, its cast-molding to specific morphologies, as well as the fusion of the biosilica nanoparticles through a biosintering mechanism. The discovery that the enzymatically formed biosilica is morphogenetically active and printable also opens new applications in rapid prototyping and three-dimensional bioprinting of customized scaffolds/implants for biomedical use.

Natural marine sponges for bone tissue engineering: The state of art and future perspectives

Marine life and its rich biodiversity provide a plentiful resource of potential new products for the society. Remarkably, marine organisms still remain a largely unexploited resource for biotechnology applications. Among them, marine sponges are sessile animals from the phylum Porifera dated at least from 580 million years ago. It is known that molecules from marine sponges present a huge therapeutic potential in a wide range of applications mainly due to its antitumor, antiviral, anti-inflammatory, and antibiotic effects. In this context, this article reviews all the information available in the literature about the potential of the use of marine sponges for bone tissue engineering applications. First, one of the properties that make sponges interesting as bone substitutes is their structural characteristics. Most species have an efficient interconnected porous architecture, which allows them to process a significant amount of water and facilitates the flow of fluids, mimicking an ideal bone scaffold. Second, sponges have an organic component, the spongin, which is analogous to vertebral collagen, the most widely used natural polymer for tissue regeneration. Last, osteogenic properties of marine sponges is also highlighted by their mineral content, such as biosilica and other compounds, that are able to support cell growth and to stimulate bone formation and mineralization. This review focuses on recent studies concerning these interesting properties, as well as on some challenges to be overcome in the bone tissue engineering field. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 1717-1727, 2017.