Flavia Libonati

Biological materials achieve remarkable combinations of mechanical performance and functionality through hierarchical architectures assembled across multiple length scales. Translating these principles into recyclable fiber‐reinforced composites remains challenging, as architecture‐enabled damage tolerance and circular material use are rarely integrated within a single design framework. Here, we report a recyclable bone‐inspired architected composite in which osteon‐like structures are assembled within an Elium thermoplastic acrylic matrix to enhance energy absorption, preserve a favorable strength‐toughness balance, and enable material recovery. Mimicking the crack‐arresting role of osteons, the embedded architecture redirects crack propagation and promotes energy dissipation, leading to a 95% increase in toughness modulus and 35% increase in strength under tensile loading compared to conventional laminates, while reduced transversal flexural performance highlights the loading‐direction‐dependent response of the discrete bone‐inspired architecture. Finite element simulations reproduce the force–displacement response and crack propagation patterns, revealing the mechanisms underlying damage tolerance. After matrix dissolution and component separation, the recovered osteon‐like structures retain tensile properties comparable to virgin counterparts. The modular architecture enables recovery of intact, aligned, load‐bearing units suitable for direct reuse without reprocessing or realignment. This work establishes a unified design and assembly strategy for recyclable bio‐inspired architected composites with coupled structural performance and circular functionality.

Understanding osteoporosis requires moving beyond bone mass alone and considering the multiscale determinants of bone quality, from extracellular matrix composition to tissue architecture and mechanical competence. Physical activity is one of the most effective non-pharmacological strategies for preserving skeletal health, suggesting that muscle-derived signals may contribute to the maintenance of bone quality during aging. Among these signals, irisin, an exercise-induced myokine, has emerged as a regulator of bone metabolism with potential benefits for skeletal structure and mechanical performance. However, whether irisin influences bone through direct interactions with matrix components or primarily through cellular and tissue-level responses remains unclear. In this study, we combine in vitro binding assays, in silico modeling, and in vivo preclinical analyses to investigate the effects of irisin on bone across multiple length scales. We examine potential interactions with type I collagen, hydroxyapatite, and heparan sulfate, and evaluate molecular, structural, and mechanical changes in aged bone. Our findings indicate that irisin enhances cortical bone mineral density, improves cortical geometry, and modulates osteogenic and mitochondrial gene expression, whereas direct binding to matrix components appears limited. These results provide new insight into how exercise-mimetic molecules may influence bone quality and support further investigation of irisin-based strategies for age-related osteoporosis.

Architectural design provides an effective pathway to tune the mechanical response of fiber-reinforced composites without altering material composition. Inspired by the concentric architecture of osteons in cortical bone, this study presents a framework for the design, modeling, and fabrication of multilayered cylindrical osteon-like structures (OLS) as reinforcements with tunable properties. A custom pull-winding technique capable of producing continuous multilayer OLS with millimeter-scale diameters was developed. The OLS were evaluated under uniaxial loading through experimental testing and finite element (FE) simulations, including representative volume element-based models, with linear and nonlinear buckling analyses performed to assess structural stability. In addition, the FE model, validated against experimental results, was used as a tool to systematically investigate the effect of stacking sequence and fiber orientation on the mechanical response of the OLS. The combined experimental and numerical analyses allowed the definition of a design space for OLS length selection considering both material strength and buckling-driven instability. The results highlight the key role of fiber orientation, with OLS configurations having fibers running parallel to the OLS axis exhibiting increased axial stiffness and improved buckling performance. This framework lays the groundwork for the future development of bio-inspired laminate systems incorporating multilayer cylindrical OLS reinforcements.

Collagen, a protein known for its long lifespan, is susceptible to accumulation of advanced glycation end products (AGEs) with age. These AGEs are considered markers that indicate the aging severity and influence the mechanics of tissues, leading to fragile bones and hardened skin. While many cross-linking AGEs have been widely studied for their ability to reduce the elasticity of biological tissues, contributing to skin hardening and fragile bones, through strong covalent bonds, non-cross-linking AGEs, or AGE adducts, are typically investigated as indicators of aging or as signaling factors in pathological conditions. However, recent experimental findings have revealed that the number of AGE adducts in aged bone is comparable to enzymatic cross-links, which are significantly more abundant than cross-linking AGEs. Based on these observations, we consider one of the most abundant AGE adducts - carboxymethyllysine (CML) - and employ molecular dynamics simulations to explore its direct impact on the mechanical and conformational properties of single tropocollagen molecules. Our models demonstrate that tropocollagen peptides, constructed based on sequences experimentally identified with sites of CML modifications in type I collagen derived from human cortical bone, exhibit heterogeneous behaviors under tensile testing. Still, most of these modified peptides display compromised structural stability, reduction in structural strength, and diminished energy dissipation ability when tension is applied. This study highlights the potential impact of non-cross-linking AGEs on collagen behavior at molecular scale and provides insights into the mechanisms underlying these modifications. Gaining a deeper understanding of the role of AGE adducts and their contribution to the aging process may pave the way for future solutions in antiaging research.

Helmets are critical for minimizing the risk of traumatic brain injuries in road accidents and sports. Traditional designs feature a rigid outer shell and a deformable inner liner of foam for energy absorption. Recent advancements have introduced architected materials as alternatives to conventional foams, offering improved safety and multifunctionality. Herein, a diatom‐inspired architected material optimized for energy absorption in helmet liners is proposed and designed for a new concept of multifunctional helmets. The material is modeled using CAD tools, its performance is evaluated through finite element analysis and quasistatic compression tests on 3D‐printed elastomeric samples, and parametric optimization is applied. The results demonstrate energy absorption comparable to conventional materials, laying the groundwork for future studies on fluid‐dynamic behavior and multifunctional helmet designs.

Diatoms have been described as “nanometer‐born lithographers” because of their ability to create sophisticated 3D amorphous silica exoskeletons. The hierarchical architecture of these structures provides diatoms with mechanical protection and the ability to filter, float, and manipulate light. Therefore, they emerge as an extraordinary model of multifunctional materials from which to draw inspiration. In this paper, numerical simulations, analytical models, and experimental tests are used to unveil the structural and fluid dynamic efficiency of the Coscinodiscus species diatom. Then a novel 3D printable multifunctional biomimetic material is proposed for applications such as porous filters, heat exchangers, drug delivery systems, lightweight structures, and robotics. The results demonstrate Nature's role as a materials designer for efficient and tunable systems and highlight the potential of diatoms for engineering materials innovation. Additionally, this paper lays the foundation to extend the structure‐property characterization of diatoms.

Diatoms have been described as nanometer-born lithographers because of their ability to create sophisticated three-dimensional amorphous silica exoskeletons. The hierarchical architecture of these structures provides diatoms with mechanical protection and the ability to filter, float, and manipulate light. Therefore, they emerge as an extraordinary model of multifunctional materials from which to draw inspiration. In this paper, we use numerical simulations, analytical models, and experimental tests to unveil the structural and fluid dynamic efficiency of the Coscinodiscus species diatom. Then we propose a novel 3D printable multifunctional biomimetic material for applications such as porous filters, heat exchangers, drug delivery systems, lightweight structures, and robotics. Our results demonstrate the role of Nature as a material designer for efficient and tunable systems and highlight the potential of diatoms for engineering materials innovation. Additionally, the results reported in this paper lay the foundation to extend the structure-property characterization of diatoms.

The primary objective of helmet design continues to be the prevention of traumatic brain injuries. Yet, achieving an optimal user experience, including aspects such as fit, thermal comfort, breathability, waterproofing, and reusability, is increasingly significant. Thus, designing helmets with multifunctional performance represents the latest technological frontier for safety devices. This study draws inspiration from the morphology of Coscinodiscus species diatoms to develop a biomimetic material replicating their cellular structure and multifunctionality. Unlike its biological counterpart, the synthetic material is engineered as the inner liner for multi impact helmets, suited for urban sports and micro mobility applications. The architecture of the material is modeled using computer aided design tools, and its energy absorption capabilities are analyzed through finite element modeling and quasi static compression tests on 3D printed elastomeric samples. Performance optimization is achieved through a parametric approach. The results demonstrate that the material exhibits energy absorption comparable to cellular materials like honeycombs, while offering lightweight properties, breathability, and resistance to atmospheric agents. This biomimetic design marks a significant advancement in high performance safety equipment.