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Understanding the crystallization of cement-binding phases, from basic units to macroscopic structures, can enhance cement performance, reduce clinker use, and lower CO2 emissions in the construction sector. This review examines the crystallization pathways of C–S–H (the main phase in PC cement) and other alternative binding phases, particularly as cement formulations evolve toward increasing SCMs and alternative binders as clinker replacements. We adopt a nonclassical crystallization perspective, which recognizes the existence of critical intermediate steps between ions in solution and the final crystalline phases, such as solute ion associates, dense liquid phases, amorphous intermediates, and nanoparticles. These multistep pathways uncover innovative strategies for controlling the crystallization of binding phases through additive use, potentially leading to highly optimized cement matrices. An outstanding example of additive-controlled crystallization in cementitious materials is the synthetically produced mesocrystalline C–S–H, renowned for its remarkable flexural strength. This highly ordered microstructure, which intercalates soft matter between inorganic and brittle C–S–H, was obtained by controlling the assembly of individual C–S–H subunits. While large-scale production of cementitious materials by a bottom-up self-assembly method is not yet feasible, the fundamental insights into the crystallization mechanism of cement binding phases presented here provide a foundation for developing advanced cement-based materials. [ABSTRACT FROM AUTHOR]

Aging society demands advanced bone implants that can achieve long‐term success through osseointegration at the bone‐implant interface. Polyetheretherketone (PEEK), a bioinert implant material, often struggles with connecting to existing bone tissue, leading to inflammation and implant replacement. Following nature's lessons, a new strategy is introduced that masks the surface of bio‐ and chemically inert Polyetheretherketone implants with a covalently anchored bone‐mimetic surface. This method transforms PEEK into a bone‐integrative material by grafting a ≈300 nm thick gelatin layer onto its surface, subsequently mineralized with calcium phosphate. Herein, it is showed that this surface modification for implant materials combines excellent bulk implant properties with the characteristic structure and functional properties of natural bone. In vitro biocompatibility assays, employing NIH‐3T3 fibroblast and MC3T3‐E1 osteoblast cell lines, confirm the enhanced biocompatibility of the modified material. This strategy offers promising prospects for improving bone implants and exemplifies the adaptation of a non‐osseointegrative material to a bone‐like interface. [ABSTRACT FROM AUTHOR]

Mineral plastics are a promising class of bio‐inspired materials that offer exceptional properties, like self‐heal ability, stretchability in the hydrogel state, and high hardness, toughness, transparency, and non‐flammability in the dry state along with reversible transformation into the hydrogel by addition of water. This enables easy reshape‐ability and recycling like the solubility in mild acids to subsequently form mineral plastics again by base addition. However, current mineral plastics rely on petrochemistry, are hardly biodegradable, and thus persistent in nature. This work presents the next generation of mineral plastics, which are bio‐based and biodegradable, making them a promising, new class of polymers for the development of environmentally friendly materials. Physically cross‐linked (poly)glutamic‐acid (PGlu)‐based mineral plastics are synthesized using various alcohol‐water mixtures, metal ion ratios and molecular weights. The rheological properties are easily adjusted using these parameters. The general procedure involves addition of equimolar solution of CaCl2 to PGlu in equal volumes followed by addition of iPrOH (iPrOH:H2O = 1:1) under vigorous stirring conditions. The ready biodegradability of PGlu/CaFe mineral plastic is confirmed in this study where the elements N, Ca, and Fe present in it tend to act as additional nutrients, supporting the growth of microorganisms and consequently, promoting the biodegradation process. [ABSTRACT FROM AUTHOR]

The low toughness under the tension of cement and concrete materials has been a long‐standing issue for decades and it has become increasingly urgent to address in modern society due to the growing demand for the development of high‐performance and sustainable constructions. Manipulating calcium silicate hydrate (C‐S‐H), the main hydration product of Portland cement, which determines the mechanical properties of cementitious materials, is an attractive method for improving their toughness following a bottom‐up approach. Inspired by the microstructure of nacre, a high energy absorption C‐S‐H‐based composite with a highly ordered structure is fabricated by a designed ternary building block, in which exfoliated montmorillonite provides a template for the nucleation and growth of C‐S‐H generating the "brick", and polyvinyl alcohol acts as a "mortar" binding all the building blocks together. With the hierarchical toughening strategy explored here, the obtained C‐S‐H composite achieves a remarkable energy absorption of 16.2 ± 2.6 MJ m−3, which surprisingly outperforms the ultra‐high toughness cementitious materials by a factor of 20–60 and is even higher than that of natural nacre and other nacre‐like composites. These findings not only provide valuable insights into enhancing the toughness of cementitious materials but also open possibilities for broadening potential applications of C‐S‐H. [ABSTRACT FROM AUTHOR]

Developing efficient and affordable electrocatalysts for the sluggish oxygen evolution reaction (OER) remains a significant barrier that needs to be overcome for the practical applications of hydrogen production via water electrolysis, transforming CO2 to value‐added chemicals, and metal‐air batteries. Recently, hydroxides have shown promise as electrocatalysts for OER. In situ or operando techniques are particularly indispensable for monitoring the key intermediates together with understanding the reaction process, which is extremely important for revealing the formation/OER catalytic mechanism of hydroxides and preparing cost‐effective electrocatalysts for OER. However, there is a lack of comprehensive discussion on the current status and challenges of studying these mechanisms using in situ or operando techniques, which hinders our ability to identify and address the obstacles present in this field. This review offers an overview of in situ or operando techniques, outlining their capabilities, advantages, and disadvantages. Recent findings related to the formation mechanism and OER catalytic mechanism of hydroxides revealed by in situ or operando techniques are also discussed in detail. Additionally, some current challenges in this field are concluded and appropriate solution strategies are provided. [ABSTRACT FROM AUTHOR]

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Medical treatment options for bones and teeth can be significantly enhanced by taking control over the crystallization of biomaterials like hydroxyapatite in the healing process. Light‐induced techniques are particularly interesting for this approach as they offer tremendous accuracy in spatial resolution. However, in the field of calcium phosphates, light‐induced crystallization has not been investigated so far. Here, proof of principle is established to successfully induce carbonate‐hydroxyapatite precipitation by light irradiation. Phosphoric acid is released by a photolabile molecule exclusively after irradiation, combining with calcium ions to form a calcium phosphate in the crystallization medium. 4‐Nitrophenylphosphate (4NPP) is established as the photolabile molecule and the system is optimized and fully characterized. A calcium phosphate is crystallized exclusively by irradiation in aqueous solution and identified as carbonate apatite. Control over the localization and stabilization of the carbonate apatite is achieved by a pulsed laser, triggering precipitation in calcium and 4NPP‐containing gel matrices. The results of this communication open up a wide range of new opportunities, both in the field of chemistry for more sophisticated reaction control in localized crystallization processes and in the field of medicine for enhanced treatment of calcium phosphate containing biomaterials. [ABSTRACT FROM AUTHOR]

Die Verwendung von kalziniertem Ton als Zementersatzstoff ist ein vielversprechender Weg, um die künftige Zementproduktion umweltfreundlicher zu gestalten und den CO2‐Fußabdruck von Beton zu verringern. Jedoch wird durch den Ersatz von kalziniertem Ton wird die Zementhydratation häufig verzögert. Obwohl die kombinierte Verwendung von Kalkstein und kalziniertem Ton mit Portlandzement die Verzögerung kompensieren kann, werden die Ursachen für diesen Effekt noch immer diskutiert. Insbesondere die Rolle der gebildeten C‐A‐S‐H‐Phasen in Kombination mit C‐S‐H‐Phasen ist umstritten. Die vorliegende Studie untersucht die geschilderte Verzögerung in Modellsystem C3S und Metakaolin. Die Hydratationsreaktionen von Metakaolin und C3S wurden mittels optischer Emissionsspektroskopie, Rasterelektronenmikroskopie, Röntgenbeugung und Reaktionskalorimetrie analysiert. Die Ergebnisse zeigen, dass Calcium‐ und Sulfationen eine dominierende Rolle für die Reaktionsgeschwindigkeit von Metakaolin spielen, was sich wiederum auf die Hydratationsgeschwindigkeit von C3S auswirkt. Die Rolle der C‐A‐S‐H‐ gegenüber der C‐S‐H‐Bildung wird in diesem Zusammenhang hervorgehoben. [ABSTRACT FROM AUTHOR]

We have developed a straightforward, one-pot, low-temperature hydrothermal method to transform oyster shell waste particles (bCCP) from the species Crassostrea gigas (Mg-calcite, 5 wt% Mg) into hydroxyapatite (HA) micro/nanoparticles. The influence of the P reagents (H3PO4, KH2PO4, and K2HPO4), P/bCCP molar ratios (0.24, 0.6, and 0.96), digestion temperatures (25–200 °C), and digestion times (1 week–2 months) on the transformation process was thoroughly investigated. At 1 week, the minimum temperature to yield the full transformation significantly reduced from 160 °C to 120 °C when using K2HPO4 instead of KH2PO4 at a P/bCCP ratio of 0.6, and even to 80 °C at a P/bCCP ratio of 0.96. The transformation took place via a dissolution–reprecipitation mechanism driven by the favorable balance between HA precipitation and bCCP dissolution, due to the lower solubility product of HA than that of calcite at any of the tested temperatures. Both the bCCP and the derived HA particles were cytocompatible for MG-63 human osteosarcoma cells and m17.ASC murine mesenchymal stem cells, and additionally, they promoted the osteogenic differentiation of m17.ASC, especially the HA particles. Because of their physicochemical features and biological compatibility, both particles could be useful osteoinductive platforms for translational applications in bone tissue engineering. [ABSTRACT FROM AUTHOR]

Cellulose is the most abundant naturally-occurring polymer, and possesses a one-dimensional (1D) anisotropic crystalline nanostructure with outstanding mechanical robustness, biocompatibility, renewability and rich surface chemistry in the form of nanocellulose in nature. Such features make cellulose an ideal bio-template for directing the bio-inspired mineralization of inorganic components into hierarchical nanostructures that are promising in biomedical applications. In this review, we will summarize the chemistry and nanostructure characteristics of cellulose and discuss how these favorable characteristics regulate the bio-inspired mineralization process for manufacturing the desired nanostructured bio-composites. We will focus on uncovering the design and manipulation principles of local chemical compositions/constituents and structural arrangement, distribution, dimensions, nanoconfinement and alignment of bio-inspired mineralization over multiple length-scales. In the end, we will underline how these cellulose biomineralized composites benefit biomedical applications. It is expected that this deep understanding of design and fabrication principles will enable construction of outstanding structural and functional cellulose/inorganic composites for more challenging biomedical applications. [ABSTRACT FROM AUTHOR]