Biosynthesis of nanomaterials is gaining attention as a sustainable, environmentally friendly, and reliable method for manufacturing a extensive array of nanostructures, such as metal/metal oxides and organic and hybrid materials. Green synthesis is considered a crucial tool to reduce the harsh effects associated with conventional synthesis. Nanocomposite materials containing biosynthesized nanostructures are highly sought after in regenerative medicine. In the present Review, biosynthesis of metal/metal oxides and carbon-based nanomaterials using microorganisms (e.g., bacteria and fungi) and natural compounds (e.g., polysaccharides, proteins, fruit juices, and plant extracts) is highlighted. The toxicity of biosynthesized nanoparticles for biomedical application is also reviewed in depth. The applications of bionanocomposites prepared from these ecofriendly nanoparticles in tissue engineering are reviewed to provide readers with a background for future studies.

Concrete is the most used material in the world. It is also one of the most versatile yet complex materials that humans have used for construction. However, an important weakness of concrete (cement-based composites) is its low tensile properties. Therefore, over the past 30 years many studies were focused on improving its tensile properties using a variety of physical and chemical methods. One of the most successful attempts is to use polymer fibers in the structure of concrete to obtain a composite with high tensile strength and ductility. The advantages of polymer fiber as reinforcing material in concrete, both with regard to reducing environmental pollution and the positive effects on a country's economy, are beyond dispute. However, a thorough understanding of the mechanical behavior of fiber-reinforced concrete requires a knowledge of fiber/matrix interfaces at the nanoscale. In this study, a combination of atomistic simulations and experimental techniques has been used to study the nanostructure of fiber/matrix interfaces. A new model for calcium-silicate-hydrate (C-S-H)/fiber interfaces is also proposed on the basis of scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX) analyses. Finally, the adhesion energy between the C-S-H gel and three different polymeric fibers (poly(vinyl alcohol), nylon-6, and polypropylene) were numerically studied at the atomistic level because adhesion plays a key role in the design of ductile fiber-reinforced composites. The mechanisms of adhesion as a function of the nanostructure of fiber/matrix interfaces are further studied and discussed. It is observed that the functional group in the structure of polymer macromolecule affects the adhesion energy primarily by changing the C/S ratio of the C-S-H at the interface and by absorbing additional positive ions in the C-S-H structure.

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