Biomimetic Enamel-like Crystals: A Versatile Platform for Unraveling the Basic Mechanisms of Demineralization and Remineralization.

Enamel is a cellular, nonregenerative, highly mineralized tissue essential for the mechanical durability and wear resistance of human teeth. Combating its degradation necessitates effective remineralization strategies, with hydroxyapatite (HAp) playing a central role in both natural and synthetic enamel restoration. Fluoride incorporation enhances HAp stability, forming fluoridated hydroxyapatite (FHAp), which is widely used to prevent or resist dental caries and improve remineralization.

Local mapping of the nanoscale viscoelastic properties of fluid membranes by AFM nanorheology.

Biological membranes are intrinsically dynamic entities that continually adapt their biophysical properties and molecular organisation to support cellular function. Current microscopy techniques can derive high-resolution structural information of labelled molecules but quantifying the associated viscoelastic behaviour with nanometre precision remains challenging. Here, we develop an approach based on atomic force microscopy in conjunction with fast nano-actuators to map the viscoelastic response of unlabelled supported membranes with nanometre spatial resolution.

Electrified Nanogaps under an AC Field: A Molecular Dynamics Study.

The organization and dynamics of ions and water molecules at electrified solid-liquid interfaces are generally well understood under static fields, especially for macroscopic electrochemical systems. In contrast, studies involving alternating (AC) fields tend to be more challenging. In nanoscale systems, added complexity can arise from interfacial interactions and the need to consider ions and molecules explicitly.

Water and ions in electrified silica nano-pores: a molecular dynamics study.

Solid-liquid interfaces (SLIs) are ubiquitous in science and technology from the development of energy storage devices to the chemical reactions occurring in the biological milieu. In systems involving aqueous saline solutions as the liquid, both the water and the ions are routinely exposed to an electric field, whether the field is externally applied, or originating from the natural surface charges of the solid. In the current study a molecular dynamics (MD) framework is developed to study the effect of an applied voltage on the behaviour of ionic solutions located in a ∼7 nm pore between two uncharged hydrophilic silica slabs.

Elucidating the role of diverse mineralisation paradigms on bone biomechanics - a coarse-grained molecular dynamics investigation.

Bone as a hierarchical composite structure plays a myriad of roles in vertebrate skeletons including providing the structural stability of the body. Despite this critical role, the mechanical behaviour at the sub-micron levels of bone's hierarchy remains poorly understood. At this scale, bone is composed of Mineralised Collagen Fibrils (MCF) embedded within an extra-fibrillar matrix that consists of hydroxyapatite minerals and non-collagenous proteins.

Osteocalcin: Promoter or Inhibitor of Hydroxyapatite Growth?

Osteocalcin is the most abundant noncollagenous bone protein and the functions in bone remineralization as well as in inhibition of bone growth have remained unclear. In this contribution, we explain the dual role of osteocalcin in the nucleation of new calcium phosphate during bone remodeling and in the inhibition of hydroxyapatite crystal growth at the molecular scale. The mechanism was derived using pH-resolved all-atom models for the protein, phosphate species, and hydroxyapatite, along with molecular dynamics simulations and experimental and clinical observations.

Ions Adsorbed at Amorphous Solid/Solution Interfaces Form Wigner Crystal-like Structures.

When a surface is immersed in a solution, it usually acquires a charge, which attracts counterions and repels co-ions to form an electrical double layer. The ions directly adsorbed to the surface are referred to as the Stern layer. The structure of the Stern layer normal to the interface was described decades ago, but the lateral organization within the Stern layer has received scant attention.

Synthesis of Chiral Triazine Frameworks for Enantiodiscrimination.

Manipulation of the structure of covalent organic frameworks at the molecular level is an efficient strategy to shift their biological, physicochemical, optical, and electrical properties in the desired windows. In this work, we report on a new method to construct chiral triazine frameworks using metal-driven polymerization for enantiodiscrimination. The nucleophilic substitution reaction between melamine and cyanuric chloride was performed in the presence of PdCl, ZnCl, and CuCl as chirality-directing agents.

Competition of opsonins and dysopsonins on the nanoparticle surface.

The biological behavior and fate of nanoparticles are dependent on their retention time in the blood circulation system. The protein corona components, especially opsonins, and dysopsonins, adsorbed on the nanoparticle surface determine their blood circulation time. The protein corona formation is a dynamic process that involves the competition between different proteins to be adsorbed on the nanoparticles.

A coarse-grained molecular dynamics investigation of the role of mineral arrangement on the mechanical properties of mineralized collagen fibrils.

Mineralized collagen fibrils (MCFs) comprise collagen molecules and hydroxyapatite (HAp) crystals and are considered universal building blocks of bone tissue, across different bone types and species. In this study, we developed a coarse-grained molecular dynamics (CGMD) framework to investigate the role of mineral arrangement on the load-deformation behaviour of MCFs. Despite the common belief that the collagen molecules are responsible for flexibility and HAp minerals are responsible for stiffness, our results showed that the mineral phase was responsible for limiting collagen sliding in the large deformation regime, which helped the collagen molecules themselves undergo high tensile loading, providing a substantial contribution to the ultimate tensile strength of MCFs.

Energy dissipation of osteopontin at a HAp mineral interface: Implications for bone biomechanics.

Osteopontin (OPN) is a one of the most abundant non-collagenous proteins in the bone's organic matrix. OPN is responsible for mediating bonding at mineral interfaces in the extrafibrillar space and recent evidence shows that it is a major contributor to bone's fracture resistance. While several experimental studies have identified an important role for calcium ions in mediating energy dissipation in OPN protein networks, the underlying molecular mechanisms remain largely unknown.

The structural role of osteocalcin in bone biomechanics and its alteration in Type-2 Diabetes.

This study presents an investigation into the role of Osteocalcin (OC) on bone biomechanics, with the results demonstrating that the protein's α-helix structures play a critical role in energy dissipation behavior in healthy conditions. In the first instance, α-helix structures have high affinity with the Hydroxyapatite (HAp) mineral surface and provide favorable conditions for adsorption of OC proteins onto the mineral surface. Using steered molecular dynamics simulation, several key energy dissipation mechanisms associated with α-helix structures were observed, which included stick-slip behavior, a sacrificial bond mechanism and a favorable binding feature provided by the Ca motif on the OC protein.

Mechanistic Understanding of the Interactions between Nano-Objects with Different Surface Properties and α-Synuclein.

Aggregation of the natively unfolded protein α-synuclein (α-syn) is key to the development of Parkinson's disease (PD). Some nanoparticles (NPs) can inhibit this process and in turn be used for treatment of PD. Using simulation strategies, we show here that α-syn self-assembly is electrostatically driven.

Disease-related metabolites affect protein-nanoparticle interactions.

Once in biological fluids, the surface of nanoparticles (NPs) is rapidly covered with a layer of biomolecules (i.e., the "protein corona") whose composition strongly determines their biological identity, regulates interactions with biological entities including cells and the immune system, and consequently directs the biological fate and pharmacokinetics of nanoparticles.