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

Tuning the Dimensionality of Polyoxometalate-Based Materials by Using a Mixture of Ligands

Five molecular one-, two-, or three-dimensional (1D, 2D, or 3D) organic–inorganic hybrid polyoxometalates (POMs) based on the {ε-PMo^V₈Mo^VI₄­O₄₀Zn₄} (εZn) Keggin unit have been synthesized under hydrothermal conditions using a mixture of O- and N-donor ligands. (TBA)₆­[PMo^V₈­Mo^VI₄O₃₇­(OH)₃Zn₄]₂­(C₁₄H₈O₄)₃­·6H₂O (<b>ε</b>_<b>2</b><b>(biphen)</b>_<b>3</b>) is a 3D material with two interpenetrated networks built from dimeric (εZn)₂ POMs linked by 4,4′-biphenyldicarboxylate (<b>biphen</b>) ligands. (TBA)₂­[PMo^V₈Mo^VI₄O₃₈­(OH)₂Zn₄]­(C₇H₆N₂)₃­(C₁₄H₈O₄)_1/2­·H₂O (<b>ε­(bim)</b>_<b>3</b><b>(biphen)</b>_<b>1/2</b>), (TBA)₃­[PMo^V₈Mo^VI₄O₃₈­(OH)₂Zn₄]­(C₇H₆N₂)₂­(C₈H₄O₄)­·6H₂O (<b>ε­(bim)</b>_<b>2</b><b>(isop)</b>), (TBA)_7/3­[PMo^V₈Mo^VI₄O₃₈­(OH)₂Zn₄]­(C₇H₆N₂)_8/3­(C₈H₄O₄)_2/3 (<b>ε­(bim)</b>_<b>8/3</b><b>(bdc)</b>_<b>2/3</b>), and (TBA)₃­[PMo^V₈Mo^VI₄O₃₈(OH)₂Zn₄]­(C₇H₆N₂)₂­(C₉H₃O₆)_2/3­·6H₂O (<b>ε­(bim)</b>_<b>2</b><b>(trim)</b>_<b>2/3</b>) all consist of monomeric εZn units bound to two types of organic ligands: benzimidazole (<b>bim</b>) and one of the following carboxylate ligands: <b>biphen</b>, 1,3-benzenedicarboxylate (<b>isop</b>), 1,4-benzenedicarboxylate (<b>bdc</b>), or 1,3,5-benzenetricarboxylate (<b>trim</b>) ligands. While <b>ε­(bim)</b>_<b>3</b><b>(biphen)</b>_<b>1/2</b> is a molecular complex, <b>ε­(bim)</b>_<b>2</b><b>(isop)</b> and <b>ε­(bim)</b>_<b>8/3</b><b>(bdc)</b>_<b>2/3</b> adopt a chain arrangement, and <b>ε­(bim)</b>_<b>2</b><b>(trim)</b>_<b>2/3</b> is a 2D compound. In these materials, the limitation of the dimensionality is a direct consequence of the protonation of the nitrogen atom of the <b>bim</b> ligands. The electrocatalytic activity for the hydrogen evolution reaction (HER) of these five new POM-based coordination polymers has been studied, showing that their performance depends mainly on the presence of the εZn Keggin units but also on their structure. Modified electrodes fabricated with <b>ε­(bim)</b>_<b>2</b><b>(trim)</b>_<b>2/3</b> entrapped in a carbon paste revealed that this hybrid is the most efficient electrocatalyst of the series, being stable and catalyzing the HER in the pH 1–5 range

Tuning the Dimensionality of Polyoxometalate-Based Materials by Using a Mixture of Ligands

Five molecular one-, two-, or three-dimensional (1D, 2D, or 3D) organic–inorganic hybrid polyoxometalates (POMs) based on the {ε-PMo^V₈Mo^VI₄­O₄₀Zn₄} (εZn) Keggin unit have been synthesized under hydrothermal conditions using a mixture of O- and N-donor ligands. (TBA)₆­[PMo^V₈­Mo^VI₄O₃₇­(OH)₃Zn₄]₂­(C₁₄H₈O₄)₃­·6H₂O (<b>ε</b>_<b>2</b><b>(biphen)</b>_<b>3</b>) is a 3D material with two interpenetrated networks built from dimeric (εZn)₂ POMs linked by 4,4′-biphenyldicarboxylate (<b>biphen</b>) ligands. (TBA)₂­[PMo^V₈Mo^VI₄O₃₈­(OH)₂Zn₄]­(C₇H₆N₂)₃­(C₁₄H₈O₄)_1/2­·H₂O (<b>ε­(bim)</b>_<b>3</b><b>(biphen)</b>_<b>1/2</b>), (TBA)₃­[PMo^V₈Mo^VI₄O₃₈­(OH)₂Zn₄]­(C₇H₆N₂)₂­(C₈H₄O₄)­·6H₂O (<b>ε­(bim)</b>_<b>2</b><b>(isop)</b>), (TBA)_7/3­[PMo^V₈Mo^VI₄O₃₈­(OH)₂Zn₄]­(C₇H₆N₂)_8/3­(C₈H₄O₄)_2/3 (<b>ε­(bim)</b>_<b>8/3</b><b>(bdc)</b>_<b>2/3</b>), and (TBA)₃­[PMo^V₈Mo^VI₄O₃₈(OH)₂Zn₄]­(C₇H₆N₂)₂­(C₉H₃O₆)_2/3­·6H₂O (<b>ε­(bim)</b>_<b>2</b><b>(trim)</b>_<b>2/3</b>) all consist of monomeric εZn units bound to two types of organic ligands: benzimidazole (<b>bim</b>) and one of the following carboxylate ligands: <b>biphen</b>, 1,3-benzenedicarboxylate (<b>isop</b>), 1,4-benzenedicarboxylate (<b>bdc</b>), or 1,3,5-benzenetricarboxylate (<b>trim</b>) ligands. While <b>ε­(bim)</b>_<b>3</b><b>(biphen)</b>_<b>1/2</b> is a molecular complex, <b>ε­(bim)</b>_<b>2</b><b>(isop)</b> and <b>ε­(bim)</b>_<b>8/3</b><b>(bdc)</b>_<b>2/3</b> adopt a chain arrangement, and <b>ε­(bim)</b>_<b>2</b><b>(trim)</b>_<b>2/3</b> is a 2D compound. In these materials, the limitation of the dimensionality is a direct consequence of the protonation of the nitrogen atom of the <b>bim</b> ligands. The electrocatalytic activity for the hydrogen evolution reaction (HER) of these five new POM-based coordination polymers has been studied, showing that their performance depends mainly on the presence of the εZn Keggin units but also on their structure. Modified electrodes fabricated with <b>ε­(bim)</b>_<b>2</b><b>(trim)</b>_<b>2/3</b> entrapped in a carbon paste revealed that this hybrid is the most efficient electrocatalyst of the series, being stable and catalyzing the HER in the pH 1–5 range