Influence of Femtosecond Laser Modification on Biomechanical and Biofunctional Behavior of Porous Titanium Substrates

[Abstract] Bone resorption and inadequate osseointegration are considered the main problems of titanium implants. In this investigation, the texture and surface roughness of porous titanium samples obtained by the space holder technique were modified with a femtosecond Yb-doped fiber laser. Different percentages of porosity (30, 40, 50, and 60 vol.%) and particle range size (100–200 and 355–500 μm) were compared with fully-dense samples obtained by conventional powder metallurgy. After femtosecond laser treatment the formation of a rough surface with micro-columns and micro-holes occurred for all the studied substrates. The surface was covered by ripples over the micro-metric structures. This work evaluates both the influence of the macro-pores inherent to the spacer particles, as well as the micro-columns and the texture generated with the laser, on the wettability of the surface, the cell behavior (adhesion and proliferation of osteoblasts), micro-hardness (instrumented micro-indentation test, P–h curves) and scratch resistance. The titanium sample with 30 vol.% and a pore range size of 100–200 μm was the best candidate for the replacement of small damaged cortical bone tissues, based on its better biomechanical (stiffness and yield strength) and biofunctional balance (bone in-growth and in vitro osseointegration).This research was funded by the Ministerio de Ciencia e Innovación del Gobierno de España (PID2019-109371GB-100), Junta de Andalucía (Spain), through the Project PAIDI P20-00671Junta de Andalucía; P20-0067

Functional materials discovery using energy–structure–function maps

Molecular crystals cannot be designed in the same manner as macroscopic objects, because they do not assemble according to simple, intuitive rules. Their structures result from the balance of many weak interactions, rather than from the strong and predictable bonding patterns found in metal–organic frameworks and covalent organic frameworks. Hence, design strategies that assume a topology or other structural blueprint will often fail. Here we combine computational crystal structure prediction and property prediction to build energy–structure–function maps that describe the possible structures and properties that are available to a candidate molecule. Using these maps, we identify a highly porous solid, which has the lowest density reported for a molecular crystal so far. Both the structure of the crystal and its physical properties, such as methane storage capacity and guest-molecule selectivity, are predicted using the molecular structure as the only input. More generally, energy–structure–function maps could be used to guide the experimental discovery of materials with any target function that can be calculated from predicted crystal structures, such as electronic structure or mechanical properties

Zeolitic imidazole frameworks: structural and energetics trends compared with their zeolite analogues

International audienceWe use periodic DFT calculations to compute the total energy of known zeolitic imidazole frameworks (ZIFs) together with those of hypothetical porous ZIFs. We show that the total energy of ZIFs decreases with increasing density, in a similar fashion to the alumino-silicate zeolites, but with a more complex energy landscape. The computational evaluation of the stability of hypothetical ZIFs is useful in the search for viable synthesis targets. Our results suggest that a number of hitherto undiscovered nanoporous topologies should be amenable to synthesis (CAN, ATN) and that even the most open framework types might be obtained with appropriately substituted ligands

Polyoxometalates Functionalized by Bisphosphonate Ligands: Synthesis, Structural, Magnetic, and Spectroscopic Characterizations and Activity on Tumor Cell Lines

International audienc

epsilon-Keggin-based coordination networks: Synthesis, structure and application toward green synthesis of polyoxometalate@graphene hybrids

Four coordination networks based on the {epsilon-(PMo8Mo4O40)-Mo-V-O-VI(OH)(4)Zn-4} Keggin unit (epsilon Zn) have been synthesized under hydrothermal conditions. (TBA)(3){(PMo8Mo4O36)-Mo-V-O-VI(OH)(4)Zn-4}[C6H4(COO)(2)](2) (epsilon(isop)(2)) is a 2D material with monomeric eZn units connected via 1,3 benzenedicarboxylate (isop) linkers and tetrabutylammonium (TBA) counter-cations lying between the planes. In (TPA)(3){(PMo8Mo4O37)-Mo-V-O-VI(OH)(3)Zn-4}[C6H3(COO)(3)] (TPA[epsilon(trim)]infinity), 1D inorganic chains formed by the connection of epsilon Zn POMs, via Zn-O bonds, are linked via 1,3,5 benzenetricarboxylate (trim) ligands into a 2D compound with tetrapropylammonium (TPA) cations as counter-cations. (TBA) {(PMo8Mo4O40Zn4)-Mo-V-O-VI}(C7H4N2)(2)(C7H5N2)(2)center dot 12H(2)O (epsilon(bim)(4)) is a molecular material with monomeric epsilon Zn POMs bound to terminal benzimidazole (bim) ligands. Finally, (TBA)(C10H10N4)(2)(HPO3) {PMo(8)(V)Mo(4)(VI)O(4)0Zn(4)}(2)(C10H9N4)(3)(C10H8N4) (epsilon(2)(pazo)(4)) is a 1D compound with dimeric (epsilon Zn)(2) POMs connected by HPO32- ions and terminal para-azobipyridine (pazo) ligands. In this compound an unusual bond cleavage of the central N=N bond of the pazo ligand is observed. We report also a green chemistry-type one-step synthesis method carried out in water at room temperature using epsilon(2)(pazo)(4) and epsilon(isop)(2) as reducing agent of graphite oxide (GO) to obtain graphene (G). The POM@G hybrids were characterized by X-ray photoelectron spectroscopy, Raman spectroscopy, powder X-ray diffraction, energy dispersive X-ray analysis, infrared spectroscopy, scanning electron microscopy, transmission electron microscopy and cyclic voltammetry