Biology subjects

Tertuliano, O.

Publications and source records attributed to Tertuliano, O..

3 recordsLinked to original sources

bioRxiv2025

Bone Resists Fatigue Through Crack Deceleration at the Fibril Scale

Bone endures millions of cycles throughout its lifetime by accumulating damage at a rate slow enough to allow for cell-mediated repair, but the mechanisms that delay this fatigue failure remain poorly understood. While prior studies have focused on the fatigue response of macroscale architecture of bone, the role of its nanoscale structure in resisting fatigue has been experimentally inaccessible. Here, we combine in-situ fatigue loading with synchrotron X-ray tomography and radiography to directly observe crack propagation in human bone with [~] 21 nm spatial and 100 ms temporal resolution. We find that mineralized collagen fibrils decelerate crack growth through branching along the fibril axes, while orthogonal cracks are intermittently decelerated by nanoscale interfibrillar interfaces. These mechanisms suppress damage accumulation under physiological loads by an order of magnitude. Our findings uncover a previously unobserved toughening strategy at the nanoscale, providing insight as to how the hierarchical structure of bone bridges the timescale gap between mechanical damage and biological repair.

bioengineering↗

bioRxiv2025

Biphasic Mechanical Loading Disrupts Cytoskeletal Symmetry in 3D Architected Scaffolds

Cells in load-bearing tissues experience both solid deformation and interstitial fluid flow during physiological loading, but the mechanisms by which they integrate these biphasic mechanical signals remain poorly understood. Here, we develop a porous, nanoarchitected 3D scaffold that allows simultaneous delivery and control of matrix strain and fluid shear stress. We validated the platform through fatigue loading experiments and simulations of fluid-structure interactions. In static culture, osteoblast-like cells adopted shapes, cytoskeletal architectures, and focal adhesion patterns templated by scaffold geometry. Under cyclic compression, the combined influence of matrix deformation and induced fluid flow disrupted this alignment, producing disordered actin structures and reduced focal adhesion eccentricity. These changes emerged even under low-frequency loading, within the drained poroelastic regime, indicating a high sensitivity of cytoskeletal organization to fluid-solid coupling. Our findings establish a tractable and tunable platform to investigate how cells sense and respond to dynamic biphasic mechanical environments in 3D. Significance StatementCells in tissues such as bone experience mechanical inputs from both matrix deformation and interstitial fluid flow. However, existing in vitro systems often isolate one type of input or lack the ability to control both independently. We engineered a nanoarchitected 3D scaffold that delivers tunable biphasic mechanical inputs by combining structural compression and fluid flow. Without external loads, cells align their cytoskeleton and focal adhesions to the scaffold geometry. When subjected to dynamic loading, they transition to disordered morphologies and less mature focal adhesions, suggesting a transition to migratory states. These results highlight the sensitivity of cells to even subtle biphasic cues and provide a new platform to study how cells integrate multiple mechanical signals in 3D environments.

bioengineering↗

bioRxiv2025

Biocompatible Multi-functional Polymeric Material for Mineralized Tissue Adhesion

This study developed a biocompatible multifunctional thiol-ene resin system for adhesion to dentin mineralized tissue. Adhesive resins maintain the strength and longevity of dental composite restorations through chemophysical bonding to exposed dentin surfaces after cavity preparations. Dental pulp cells are exposed to residual monomers transported through dentinal tubules. Monomers of conventional adhesive systems may result in inhomogeneous polymer networks and the release of residual monomers that cause cytotoxicity. In this study, we develop a one-step multi-functional polymeric resin system by incorporating trimethylolpropane triacrylate (TMPTA) and bis[2-(methacryloyloxy)ethyl] phosphate (BMEP) to enhance both mechanical properties and adhesion to dentin. Molecular dynamics simulations identified an optimal triacylate:trithiol ratio of 2.5:1, which was consistent with rheological and mechanical tests that yielded a storage modulus of ~30 MPa with or without BMEP. Shear bond tests demonstrated that the addition of BMEP significantly improved dentin adhesion, achieving a shear bond strength of 10.8 MPa, comparable to the commercial primer Clearfil SE Bond. Nanoindentation modulus mapping characterized the hybrid layer and mechanical gradient of the adhesive resin system. Further, the triacrylate-BMEP resin showed biocompatibility with fibroblasts in vitro. These findings suggest the triacrylate-trithiol crosslinking and chemophysical bonding of BMEP provide enhanced bond strength and biocompatibility for dental applications.

bioengineering↗