Caracterización de la impedancia eléctrica de implantes de titanio poroso modificados superficialmente con láser femtosegundo

En este trabajo, se evalúa la impedancia eléctrica de distintas muestras de titanio poroso modificadas superficialmente con un láser de femtosegundo; como método experimental para caracterizar la macroporosidad inherente al proceso de fabricación y el efecto del tratamiento superficial de los discos. El estudio se realiza sobre discos con distinto contenido en volumen y rango de tamaño de poros. Las medidas de impedancia eléctrica se realizaron usando el Hewkett-Packard 4395A de Agilent. Los resultados revelan la potencialidad de esta técnica de medida en términos de ventajas frente a técnicas más engorrosas y costosas, permitiendo de forma semi-cuantitativa relacionar las medidas de impedancia con el contenido y tamaño de los poros, así como detectar el efecto de la modificación superficial generada con el láser de femtosegundo (microporosidad adicional y capa de óxido de titanio)

Enhancement of the intrinsic fluorescence of ZIF-8 via post-synthetic cation exchange with Cd2+ and its incorporation into PDMS films for selective sulfide optical sensing

In this study, ZIF-8 MOF nanocrystals were synthesized and post-synthetically modified by applying different cation exchange strategies. Addition of cadmium nitrate in either methanol or DMF followed by either magnetic stirring or gentle heating led to the incorporation of a small amount of Cd (II) ions into the crystal structure in most cases, as clearly demonstrated by several characterization techniques including PXRD, SEM-EDS and FT-IR. This novel doped material exhibits a high fluorescence with the maximum emission wavelength at 444 nm upon excitation at 380 nm, which allows its use as an effective optical sensor. The sensing capability of the Cd-doped ZIF-8 material was demonstrated by its exposure to sulfide ions in aqueous solution. The fluorescence of the doped material was gradually quenched as the concentration of S2− was increased. Sensing devices based on mixed-matrix membranes (MMMs) were fabricated by using poly (dimethyl siloxane) (PDMS) as a hosting matrix for the Cd-doped ZIF-8 crystals, giving rise to fluorescent sensing films with fast and selective responses against a broad number of potential interferents

Electrical Impedance of Surface Modified Porous Titanium Implants with Femtosecond Laser

The chemical composition and surface topography of titanium implants are essential to improve implant osseointegration. The present work studies a non-invasive alternative of electrical impedance spectroscopy for the characterization of the macroporosity inherent to the manufacturing process and the effect of the surface treatment with femtosecond laser of titanium discs. Osteoblasts cell culture growths on the titanium surfaces of the laser-treated discs were also studied with this method. The measurements obtained showed that the femtosecond laser treatment of the samples and cell culture produced a significant increase (around 50%) in the absolute value of the electrical impedance module, which could be characterized in a wide range of frequencies (being more relevant at 500 MHz). Results have revealed the potential of this measurement technique, in terms of advantages, in comparison to tiresome and expensive techniques, allowing semi-quantitatively relating impedance measurements to porosity content, as well as detecting the effect of surface modification, generated by laser treatment and cell culture.Ministry of Science and Innovation of Spain grant PID2019-109371GB-I00Junta de Andalucía–FEDER (Spain) Project US-1259771Junta de Andalucía-Proyecto de Excelencia (Spain) P18-FR-203

Tribo-mechanical and cellular behavior of superficially modified porous titanium samples using femtosecond laser

Abstract: In this work, the surface of porous titanium samples obtained by the space-holder technique was treated with a femtosecond laser to improve their osseointegration. Instrumented micro-indentation and scratch test were implemented to evaluate the tribo-mechanical behavior of the surface of the modified samples. A detailed study of micro-hardness, stiffness, scratch resistance and elastic recovery was performed. Also, in vitro analysis was carried out to evaluate the cellular behavior. Modified samples showed less ALP activity, which could indicate a greater differentiation of the cells. The cell culture was similar in all cases although more differentiated morphology, good cell adherence and biological response were observed on treated samples. Finally, the discs with a pore size between 100–200 μm present being potential candidates for the replacement of small portions of damaged cortical bone tissues.Ministerio de Ciencia e Innovación; PID2019-109371GB-I00 Junta de Andalucía; US-125977

Porous beta titanium alloy coated with a therapeutic biopolymeric composite to improve tribomechanical and biofunctional balance

Tooth loss is common in patients struggling with dental cavities, periodontal diseases, and tumors, as well as those who abuse tobacco or drugs. In this scenario, dental implants have become the primary treatment option for complete or partial tooth loss. Dental implant failure can be caused by stress shielding phenomenon, poor osseointegration, or to bacterial infections. In the present study, a joint solution to these limitations is proposed using a variety of porous β-titanium substrates using powder Ti35Nb7Zr5Ta alloy and employing the spacer-holder approach (ammonium bicarbonate) to obtain a variety of porosity percentage (30, 40, and 50 vol%), and pore diameters in 100–200 μm, that has been characterized in terms of its size distribution, density, morphology, chemical composition, compaction ability and Vickers micro-hardness. Furthermore, porosity, microstructure (Archimedes and image analysis) and tribomechanical behavior (P-h curves and scratch tests) experiments were performed to study and characterize the porous substrates. Polyvinyl alcohol (PVA)/poly-ε-caprolactone (PCL) containing silver nanoparticles (AgNPs), as antibacterial composite, was employed to infiltrate β-Ti disks. Scanning electron microscopy was used to determine the coating morphology, thickness, and infiltration of the porous substrates. Wettability and SBF experiments were also carried out to investigate hydrophobicity and potential biofunctionality. The results suggested how the porosity of the β-Ti alloy affects the mechanical characteristics and the wettability of the substrate that was successfully infiltrated to exert an antimicrobial behavior

Versatile Biodegradable Poly(acrylic acid)-Based Hydrogels Infiltrated in Porous Titanium Implants to Improve the Biofunctional Performance

This research work proposes a synergistic approach to improve implants’ performance through the use of porous Ti substrates to reduce the mismatch between Young’s modulus of Ti (around 110 GPa) and the cortical bone (20−25 GPa), and the application of a biodegradable, acrylic acid-based polymeric coating to reduce bacterial adhesion and proliferation, and to enhance osseointegration. First, porous commercially pure Ti substrates with different porosities and pore size distributions were fabricated by using space-holder techniques to obtain substrates with improved tribomechanical behavior. On the other hand, a new diacrylate cross-linker containing a reductionsensitive disulfide bond was synthesized to prepare biodegradable poly(acrylic acid)-based hydrogels with 1, 2, and 4% cross-linker. Finally, after the required characterization, both strategies were implemented, and the combination of 4% cross-linked poly(acrylic acid)-based hydrogel infiltrated in 30 vol % porosity, 100− 200 μm average pore size, was revealed as an outstanding choice for enhancing implant performance.Premio Anual Publicación Científica Destacada de la US. Facultad de Farmaci

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

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

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).Ministerio de Ciencia e Innovación del Gobierno de España PID2019-109371GB-100Junta de Andalucía (Spain) PAIDI P20-0067

Novel Utilization of Therapeutic Coatings Based on Infiltrated Encapsulated Rose Bengal Microspheres in Porous Titanium for Implant Applications

Despite the increasing progress achieved in the last 20 years in both the fabrication of porous dental implants and the development of new biopolymers for targeting drug therapy, there are important issues such as bone resorption, poor osseointegration, and bacterial infections that remain as critical challenges to avoid clinical failure problems. In this work, we present a novel microtechnology based on polycaprolactone microspheres that can adhere to porous titanium implant models obtained by the spacer holder technique to allow a custom biomechanical and biofunctional balance. For this purpose, a double emulsion solvent evaporation technique was successfully employed for the fabrication of the microparticles properly loaded with the antibacterial therapeutic agent, rose bengal. The resulting microspheres were infiltrated into porous titanium substrate and sintered at 60 °C for 1 h, obtaining a convenient prophylactic network. In fact, the sintered polymeric microparticles were demonstrated to be key to controlling the drug dissolution rate and favoring the early healing process as consequence of a better wettability of the porous titanium substrate to promote calcium phosphate nucleation. Thus, this joint technology proposes a suitable prophylactic tool to prevent both early-stage infection and late-stage osseointegration problems

Electrical Impedance of Surface Modified Porous Titanium Implants with Femtosecond Laser

The chemical composition and surface topography of titanium implants are essential to improve implant osseointegration. The present work studies a non-invasive alternative of electrical impedance spectroscopy for the characterization of the macroporosity inherent to the manufacturing process and the effect of the surface treatment with femtosecond laser of titanium discs. Osteoblasts cell culture growths on the titanium surfaces of the laser-treated discs were also studied with this method. The measurements obtained showed that the femtosecond laser treatment of the samples and cell culture produced a significant increase (around 50%) in the absolute value of the electrical impedance module, which could be characterized in a wide range of frequencies (being more relevant at 500 MHz). Results have revealed the potential of this measurement technique, in terms of advantages, in comparison to tiresome and expensive techniques, allowing semi-quantitatively relating impedance measurements to porosity content, as well as detecting the effect of surface modification, generated by laser treatment and cell culture