Seriation of Enzyme-Functionalized Multilayers for the Design of Scalable Biomimetic Mineralized Structures.

Biomimetic hydroxyapatites are widely explored for their potential applications in the repair of mineralized tissues, particularly dental enamel, which is acellular and, thus, not naturally reformed after damage. Enamel is formed with a highly-controlled hierarchical structure, which is difficult to replicate up to the macroscale. A biomimetic approach is thus warranted, based on the same principles that drive biomineralization in vivo.

Correction: Factors impacting the aggregation/agglomeration and photocatalytic activity of highly crystalline spheroid- and rod-shaped TiO nanoparticles in aqueous solutions.

Correction for 'Factors impacting the aggregation/agglomeration and photocatalytic activity of highly crystalline spheroid- and rod-shaped TiO nanoparticles in aqueous solutions' by Thomas Degabriel, Elodie Colaço , , 2018, , 12898-12907, https://doi.org/10.1039/C7CP08054A.

Tunable Enzyme-Assisted Mineralization of Apatitic Calcium Phosphate by Homogeneous Catalysis.

While it has long been mimicked by simple precipitation reactions under biologically relevant conditions, calcium phosphate biomineralization is a complex process, which is highly regulated by physicochemical factors and involves a variety of proteins and other biomolecules. Alkaline phosphatase (ALP), in particular, is a conductor of sorts, directly regulating the amount of orthophosphate ions available for mineralization. Herein, we explore enzyme-assisted mineralization in the homogeneous phase as a method for biomimetic mineralization and focus on how relevant ionic substitution types affect the obtained minerals.

Deep reinforcement learning coupled with musculoskeletal modelling for a better understanding of elderly falls.

Reinforcement learning (RL) has been used to study human locomotion learning. One of the current challenges in healthcare is our understanding of and ability to slow the decline due to muscle ageing and its effect on human falls. The purpose of this study was to investigate reinforcement learning for human movement strategies when modifying muscle parameters to account for age-related changes.

Embedding Collagen in Multilayers for Enzyme-Assisted Mineralization: A Promising Way to Direct Crystallization in Confinement.

The biogenic calcium phosphate (CaP) crystallization is a process that offers elegant materials design strategies to achieve bioactive and biomechanical challenges. Indeed, many biomimetic approaches have been developed for this process in order to produce mineralized structures with controlled crystallinity and shape. Herein, we propose an advanced biomimetic approach for the design of ordered hybrid mineralized nano-objects with highly anisotropic features.

First step to the improvement of the blood brain barrier passage of atazanavir encapsulated in sustainable bioorganic vesicles.

The blood - brain barrier (BBB) prevents the majority of therapeutic drugs from reaching the brain following intravenous or oral administration. In this context, polymer nanoparticles are a promising alternative to bypass the BBB and carry drugs to brain cells. Amphiphilic cyclodextrins can form self-assemblies whose nanoparticles have a 100-nm-diameter range and are thus able to encapsulate drugs for controlled release.

Hierarchical Collagen-Hydroxyapatite Nanostructures Designed through Layer-by-Layer Assembly of Crystal-Decorated Fibrils.

A comprehensive understanding of the mechanism by which type I collagen (Col) interacts with hydroxyapatite nanoparticles (Hap NPs) in aqueous solutions is a pivotal step for guiding the design of biologically relevant nanocomposites with controlled hierarchical structure. In this paper we use a variety of Hap NPs differing by their shape (rod vs platelet) and their size (∼30 vs ∼130 nm) and investigate their mechanism(s) of interaction with collagen. The addition of collagen to the Hap suspensions induces different effects that strongly depend on the nanoparticle type.

Layer-by-Layer Assembly of Nanosized Membrane Fractions for the Assessment of Cytochrome P450 Xenobiotic Metabolism.

Herein, we report the use of sequential layer-by-layer (LbL) assembly to design nanostructured films made of recombinant bacterial membrane fractions (MF), which overexpress cytochrome P450 (CYP) and cytochrome P450 reductase. The ability to incorporate MF in LbL multilayered films is demonstrated by an in situ quartz crystal microbalance with dissipation monitoring using poly-l-lysine or poly-l-ornithine as a polycation. Results show that MF preserve a remarkable CYP1A2 catalytic property in the adsorbed phase.

Factors impacting the aggregation/agglomeration and photocatalytic activity of highly crystalline spheroid- and rod-shaped TiO nanoparticles in aqueous solutions.

We investigate the characteristics, fate and photocatalytic activity of spheroid- and rod-shaped TiO2 nano-crystals in aqueous solutions to better understand their behaviour in media of biological and environmental interest. For this purpose, the potential of a solvothermal method in synthesizing highly crystalline nanoparticles and tuning their sizes/shapes is explored. Spheroid- and rod-shaped nanoparticles are successfully obtained with different aspect ratios, while keeping their structures as well as their cross-sectional areas identical.

Synthesis, iron(III) complexation properties, molecular dynamics simulations and P. aeruginosa siderophore-like activity of two pyoverdine analogs.

P. aeruginosa ranks among the top five organisms causing nosocomial infections. Among the many novel strategies for developing new therapeutics against infection, targeting iron uptake mechanism seems promising as P.

Antioxidant and Membrane Binding Properties of Serotonin Protect Lipids from Oxidation.

Serotonin (5-hydroxytryptamine, 5-HT) is a well-known neurotransmitter that is involved in a growing number of functions in peripheral tissues. Recent studies have shown nonpharmacological functions of 5-HT linked to its chemical properties. Indeed, it was reported that 5-HT may, on the one hand, bind lipid membranes and, on the other hand, protect red blood cells through a mechanism independent of its specific receptors.

Lipid Layers on Nanoscale Surface Topography: Stability and Effect on Protein Adsorption.

Herein, we report the coating of a surface with a random nanoscale topography with a lipid film formed by an anchoring stearic acid (SA) monolayer and phospholipid (DPPC) layers. For this purpose, different procedures were used for phospholipid coating, including adsorption from solution, drop deposition, and spin-coating. Our results reveal that the morphology of the obtained lipid films is strongly influenced by the topography of the underlying substrate but also impacted by other factors, including the coating procedure and surface wettability (modulated by the presence of SA).

Hematin loses its membranotropic activity upon oligomerization into malaria pigment.

Malaria is an infectious disease caused by Plasmodium type parasites transmitted by the bites of infected female anopheles mosquitoes. The malaria parasite multiplies in red blood cells where it degrades hemoglobin. This degradation of hemoglobin proteins releases hematin, an iron-containing porphyrin, which provokes membrane disruption and lysis.

Topological effects and binding modes operating with multivalent iminosugar-based glycoclusters and mannosidases.

Multivalent iminosugars have been recently explored for glycosidase inhibition. Affinity enhancements due to multivalency have been reported for specific targets, which are particularly appealing when a gain in enzyme selectivity is achieved but raise the question of the binding mode operating with this new class of inhibitors. Here we describe the development of a set of tetra- and octavalent iminosugar probes with specific topologies and an assessment of their binding affinities toward a panel of glycosidases including the Jack Bean α-mannosidase (JBαMan) and the biologically relevant class II α-mannosidases from Drosophila melanogaster belonging to glycohydrolase family 38, namely Golgi α-mannosidase ManIIb (GM) and lysosomal α-mannosidase LManII (LM).

Probing the nature of the cluster effect observed with synthetic multivalent galactosides and peanut agglutinin lectin.

We designed a set of multi-galactosides with valencies ranging from one to seven and different spacer-arm lengths. The compounds display a high structural homology for a strict assessment of multivalent phenomena. The multimers were first evaluated by an enzyme-linked lectin assay (ELLA) toward the peanut agglutinin (PNA).

Effects of surfactin on membrane models displaying lipid phase separation.

Surfactin, a bacterial amphiphilic lipopeptide is attracting more and more attention in view of its bioactive properties which are in relation with its ability to interact with lipids of biological membranes. In this work, we investigated the effect of surfactin on membrane structure using model of membranes, vesicles as well as supported bilayers, presenting coexistence of fluid-disordered (DOPC) and gel (DPPC) phases. A range of complementary methods was used including AFM, ellipsometry, dynamic light scattering, fluorescence measurements of Laurdan, DPH, calcein release, and octadecylrhodamine B dequenching.

Atomic force microscopy of model lipid membranes.

Supported lipid bilayers (SLBs) are biomimetic model systems that are now widely used to address the biophysical and biochemical properties of biological membranes. Two main methods are usually employed to form SLBs: the transfer of two successive monolayers by Langmuir-Blodgett or Langmuir-Schaefer techniques, and the fusion of preformed lipid vesicles. The transfer of lipid films on flat solid substrates offers the possibility to apply a wide range of surface analytical techniques that are very sensitive.

Titanium dioxide nanoparticles disturb the fibronectin-mediated adhesion and spreading of pre-osteoblastic cells.

In the context of rapid development of nanoparticles (NPs) for industrial applications, the question of their toxicity and biological effects must be considered. In this work, we have assessed the influence of titanium dioxide NPs on the adhesion and spreading of MC-3T3 pre-osteoblasts by using a cell subclone that does not produce its own extracellular matrix. Petri dishes were coated with the important adhesion protein fibronectin (Fn).

Preosteoblasts and fibroblasts respond differently to anatase titanium dioxide nanoparticles: a cytotoxicity and inflammation study.

There is a bundle of proofs suggesting that some industrial nanoparticles (NPs) can provoke diseases and pollute the environment durably. However, these issues still remain controversial. In the biomedical field, TiO(2) NPs were recently proposed to serve as fillers in polymeric materials to improve bone prostheses and scaffolds.

The natural antioxidant rosmarinic acid spontaneously penetrates membranes to inhibit lipid peroxidation in situ.

Exogenous molecules from dietary sources such as polyphenols are very efficient in preventing the alteration of lipid membranes by oxidative stress. Among the polyphenols, we have chosen to study rosmarinic acid (RA). We investigated the efficiency of RA in preventing lipid peroxidation and in interacting with lipids.

The potent antimalarial peptide cyclosporin A induces the aggregation and permeabilization of sphingomyelin-rich membranes.

Cyclosporin A (CsA) is a hydrophobic peptide drug produced by the fungus Tolypocladium inflatum. CsA is commonly used as an immunosuppressive drug, but it also has antimalarial activity. The immunosuppressive activity of CsA is clearly due to its association with specific proteins of immune cells such as cyclophilins.

Cytochrome c provokes the weakening of zwitterionic membranes as measured by force spectroscopy.

Cytochrome c (cyt c) is a small soluble protein from the intermembrane space of mitochondria. This protein is essential because it transfers electrons between two membrane complexes of the respiratory chain. In fact, during this transfer, the positively charged amino-acid residues surrounding the heme in the protein structure allow the cyt c to interact properly with the anionic part of other molecules: mainly the cardiolipin-rich membrane of mitochondria and respiratory complexes.

Preparation of an electrochemical biosensor based on lipid membranes in nanoporous alumina.

Model lipid bilayers are versatile tools to investigate the molecular processes occurring at the membrane level. Among the model membranes, substrate supported bilayers have attracted much interest because they are robust and they can be investigated by powerful surface sensitive techniques such as electrochemical measurements. In a biosensor, lipid films can be used not only as a support for the biological sensing elements but also as sensing elements themselves to detect molecules that are able to alter the structure and the properties of biomembranes.

Cytochrome c interaction with neutral lipid membranes: influence of lipid packing and protein charges.

The interaction of cytochrome c (cyt c) with fluid/gel neutral supported lipid membranes was investigated by time-lapse atomic force microscopy (AFM). AFM revealed the random formation of depressed areas in fluid membranes promoted by cyt c. These depressions corresponded to the desorption of fluid bilayer patches induced by cyt c.

The potent antimalarial drug cyclosporin A preferentially destabilizes sphingomyelin-rich membranes.

Cyclosporin A (CsA) is a hydrophobic cyclic peptide produced by a fungus. CsA is widely used as an immunosuppressive agent to inhibit the rejection of transplanted organs. CsA also exhibits an antiparasitic activity against Plasmodium, the microorganism responsible for malaria disease.