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Bacterial infection remains a significant problem associated with orthopaedic surgeries leading to surgical site infection (SSI). This unmet medical need can become an even greater complication when surgery is due to malignant bone tumor. In the present study, we evaluated in vitro titanium (Ti) implants subjected to gallium (Ga) and silver (Ag)-doped thermochemical treatment as strategy to prevent SSI and improve osteointegration in bone defects caused by diseases such as osteoporosis, bone tumor, or bone metastasis. Firstly, as Ga has been reported to be an osteoinductive and anti-resorptive agent, its performance in the mixture was proved by studying human mesenchymal stem cells (hMSC) and pre-osteoclasts (RAW264.7) behaviour. Then, the antibacterial potential provided by Ag was assessed by resembling “The Race for the Surface” between hMSC and Pseudomonas aeruginosa in two co-culture methods. Moreover, the presence of quorum sensing molecules in the co-culture was evaluated. The results highlighted the suitability of the mixture to induce osteodifferentiation and reduce osteoclastogenesis in vitro. Furthermore, the GaAg surface promoted strong survival rate and retained osteoinduction potential of hMSCs even after bacterial inoculation. Therefore, GaAg-modified titanium may be an ideal candidate to repair bone defects caused by excessive bone resorption, in addition to preventing SSI., Peer Reviewed, Postprint (published version)

Previously, functional coatings on 3D-printed titanium implants were developed to improve their biointegration by separately incorporating Ga and Ag on the biomaterial surface. Now, a thermochemical treatment modification is proposed to study the effect of their simultaneous incorporation. Different concentrations of AgNO3 and Ga(NO3)3 are evaluated, and the obtained surfaces are completely characterized. Ion release, cytotoxicity, and bioactivity studies complement the characterization. The provided antibacterial effect of the surfaces is analyzed, and cell response is assessed by the study of SaOS-2 cell adhesion, proliferation, and differentiation. The Ti surface doping is confirmed by the formation of Ga-containing Ca titanates and nanoparticles of metallic Ag within the titanate coating. The surfaces generated with all combinations of AgNO3 and Ga(NO3)3 concentrations show bioactivity. The bacterial assay confirms a strong bactericidal impact achieved by the effect of both Ga and Ag present on the surface, especially for Pseudomonas aeruginosa, one of the main pathogens involved in orthopedic implant failures. SaOS-2 cells adhere and proliferate on the Ga/Ag-doped Ti surfaces, and the presence of gallium favors cell differentiation. The dual effect of both metallic agents doping the titanium surface provides bioactivity while protecting the biomaterial from the most frequent pathogens in implantology., Peer Reviewed, Postprint (published version)

Excessive bone resorption is one of the main causes of bone homeostasis alterations, resulting in an imbalance in the natural remodeling cycle. This imbalance can cause diseases such as osteoporosis, or it can be exacerbated in bone cancer processes. In such cases, there is an increased risk of fractures requiring a prosthesis. In the present study, a titanium implant subjected to gallium (Ga)-doped thermochemical treatment was evaluated as a strategy to reduce bone resorption and improve osteodifferentiation. The suitability of the material to reduce bone resorption was proven by inducing macrophages (RAW 264.7) to differentiate to osteoclasts on Ga-containing surfaces. In addition, the behavior of human mesenchymal stem cells (hMSCs) was studied in terms of cell adhesion, morphology, proliferation, and differentiation. The results proved that the Ga-containing calcium titanate layer is capable of inhibiting osteoclastogenesis, hypothetically by inducing ferroptosis. Furthermore, Ga-containing surfaces promote the differentiation of hMSCs into osteoblasts. Therefore, Ga-containing calcium titanate may be a promising strategy for patients with fractures resulting from an excessive bone resorption disease., The authors declare financial support was received for the research, authorship, and/or publication of this article. This work was supported by the Ministry of Science and Innovation of Spain through the RTI 2018-098075-B-C21 project, cofounded by the EU through the European Regional Development Funds (MINECO-FEDER, EU). The authors also thank the Spanish Government for financial support through PID 2021-125150OB-I00 project, as well as the FPI-MEC scholarship of DP-A., Peer Reviewed, Postprint (published version)

The Boston keratoprosthesis (BKPro) is a medical device used to restore vision in complicated cases of corneal blindness. This device is composed by a front plate of polymethylmethacrylate (PMMA) and a backplate usually made of titanium (Ti). Ti is an excellent biomaterial with numerous applications, although there are not many studies that address its interaction with ocular cells. In this regard, despite the good retention rates of the BKPro, two main complications compromise patients' vision and the viability of the prosthesis: imperfect adhesion of the corneal tissue to the upside of the backplate and infections. Thus, in this work, two topographies (smooth and rough) were generated on Ti samples and tested with or without functionalization with a dual peptide platform. This molecule consists of a branched structure that links two peptide moieties to address the main complications associated with BKPro: the well-known RGD peptide in its cyclic version (cRGD) as cell pro-adherent motif and the first 11 residues of lactoferrin (LF1–11) as antibacterial motif. Samples were physicochemically characterized, and their biological response was evaluated in vitro with human corneal keratocytes (HCKs) and against the gram-negative bacterial strain Pseudomonas aeruginosa. The physicochemical characterization allowed to verify the functionalization in a qualitative and quantitative manner. A higher amount of peptide was anchored to the rough surfaces. The studies performed using HCKs showed increased long-term proliferation on the functionalized samples. Gene expression was affected by topography and peptide functionalization. Roughness promoted a-smooth muscle actin (a-SMA) overexpression, and the coating notably increased the expression of extracellular matrix components (ECM). Such changes may favour the development of unwanted fibrosis, and thus, corneal haze. In contrast, the combination of the coating with a rough topography decreased the expression of a-SMA and ECM c, Peer Reviewed, Postprint (published version)

The formation of a biological seal around the neck of titanium (Ti) implants is critical for ensuring integration at the gingival site and for preventing bacterialcolonization that may lead to periimplantitis. This process is guided byactivated fibroblasts, named myofibroblasts, which secrete extracellularmatrix (ECM) proteins and ECM-degrading enzymes resolving the wound.However, in some cases, Ti is not able to attract and activate fibroblasts to asufficient extent, which may compromise the success of the implant.Fibronectin (FN) is an ECM component found in wounds that is able to guidesoft tissue healing through the adhesion of cells and attraction of growthfactors (GFs). However, clinical use of FN functionalized Ti implants isproblematic because FN is difficult to obtain, and is sensitive to degradation.Herein, functionalizing Ti with a modified recombinant heparin binding II(HBII) domain of FN, mutated to include an Arg-Gly-Asp (RGD) sequence forpromoting both fibroblast adhesion and GF attraction, is aimed at. TheHBII-RGD domain is able to stimulate fibroblast adhesion, spreading,proliferation, migration, and activation to a greater extent than the nativeHBII, reaching values closer to those of full-length FN suggesting that itmight induce the formation of a biological sealing., Peer Reviewed, Postprint (published version)

Titanium implantation success may be compromised by Staphylococcus aureus surface colonization and posterior infection. To avoid this issue, different strategies have been investigated to promote an antibacterial character to titanium. In this work, two antibacterial agents (silver nanoparticles and a multifunctional antimicrobial peptide) were used to coat titanium surfaces. The modulation of the nanoparticle (˜32.1 ± 9.4 nm) density on titanium could be optimized, and a sequential functionalization with both agents was achieved through a two-step functionalization method by means of surface silanization. The antibacterial character of the coating agents was assessed individually as well as combined. The results have shown that a reduction in bacteria after 4 h of incubation can be achieved on all the coated surfaces. After 24 h of incubation, however, the individual antimicrobial peptide coating was more effective than the silver nanoparticles or their combination against Staphylococcus aureus. All tested coatings were non-cytotoxic for eukaryotic cells., Peer Reviewed, Postprint (author's final draft)

The 3D printing of titanium (Ti) offers countless possibilities for the development of personalized implants with suitable mechanical properties for different medical applications. However, the poor bioactivity of Ti is still a challenge that needs to be addressed to promote scaffold osseointegration. The aim of the present study was to functionalize Ti scaffolds with genetically modified elastin-like recombinamers (ELRs), synthetic polymeric proteins containing the elastin epitopes responsible for their mechanical properties and for promoting mesenchymal stem cell (MSC) recruitment, proliferation, and differentiation to ultimately increase scaffold osseointegration. To this end, ELRs containing specific cell-adhesive (RGD) and/or osteoinductive (SNA15) moieties were covalently attached to Ti scaffolds. Cell adhesion, proliferation, and colonization were enhanced on those scaffolds functionalized with RGD-ELR, while differentiation was promoted on those with SNA15-ELR. The combination of both RGD and SNA15 into the same ELR stimulated cell adhesion, proliferation, and differentiation, although at lower levels than those for every single moiety. These results suggest that biofunctionalization with SNA15-ELRs could modulate the cellular response to improve the osseointegration of Ti implants. Further investigation on the amount and distribution of RGD and SNA15 moieties in ELRs could improve cell adhesion, proliferation, and differentiation compared to the present study., Peer Reviewed, Postprint (published version)

The rapid integration in the bone tissue and the prevention of bacterial infection are key for the success of the implant. In this regard, a silver (Ag)-doped thermochemical treatment that generate an Ag-doped calcium titanate layer on titanium (Ti) implants was previously developed by our group to improve the bone-bonding ability and provide antibacterial activity. In the present study, the biological and antibacterial potential of this coating has been further studied. In order to prove that the Ag-doped layer has an antibacterial effect with no detrimental effect on the bone cells, the behavior of osteoblast-like cells in terms of cell adhesion, morphology, proliferation and differentiation was evaluated, and the biofilm inhibition capacity was assessed. Moreover, the competition by the surface between cell and bacteria was carried out in two different co-culture methods. Finally, the treatment was applied to porous Ti implants to study in vivo osteointegration. The results show that the incorporation of Ag inhibits the biofilm formation and has no effect on the performance of osteoblast-like cells. Therefore, it can be concluded that the Ag-doped surface is capable of preventing bone bacterial infection and providing suitable osseointegration., Postprint (published version)

The passivation of titanium dental implants is performed in order to clean the surface and obtain a thin layer of protective oxide (TiO2) on the surface of the material in order to improve its behavior against corrosion and prevent the release of ions into the physiological environment. The most common chemical agent for the passivation process is hydrochloric acid (HCl), and in this work we intend to determine the capacity of citric acid as a passivating and bactericidal agent. Discs of commercially pure titanium (c.p.Ti) grade 4 were used with different treatments: control (Ctr), passivated by HCl, passivated by citric acid at 20% at different immersion times (20, 30, and 40 min) and a higher concentration of citric acid (40%) for 20 min. Physical-chemical characterization of all of the treated surfaces has been carried out by scanning electronic microscopy (SEM), confocal microscopy, and the ‘Sessile Drop’ technique in order to obtain information about different parameters (topography, elemental composition, roughness, wettability, and surface energy) that are relevant to understand the biological response of the material. In order to evaluate the corrosion behavior of the different treatments under physiological conditions, open circuit potential and potentiodynamic tests have been carried out. Additionally, ion release tests were realized by means of ICP-MS. The antibacterial behavior has been evaluated by performing bacterial adhesion tests, in which two strains have been used: Pseudomonas aeruginosa (Gram–) and Streptococcus sanguinis (Gram+). After the adhesion test, a bacterial viability study has been carried out (‘Life and Death’) and the number of colony-forming units has been calculated with SEM images. The results obtained show that the passivation with citric acid improves the hydrophilic character, corrosion resistance, and presents a bactericide character in comparison with the HCl treatment. The increasing of citric acid concentration improves the, Peer Reviewed, Postprint (author's final draft)

The use of a PMMA composite with graphene is being commercialized for application as dental prostheses. The different proportions of fibers provide a wide range of colors that favors dental esthetics in prostheses. However, there are no studies that have explained the influence that graphene has on the mechanical properties. In this contribution, we studied the PMMA and PMMA material with graphene fibers (PMMA-G) in the form of discs as supplied for machining. The presence of graphene fibers has been studied by Raman spectroscopy and the Shore hardness and Vickers micro hardness were determined. Mechanical compression tests were carried out to obtain the values of maximum strength and Young’s modulus (E) and by means of pin-on-disc wear tests, the specific wear rate and the friction coefficients were determined following the established international standards. Finally, the samples were characterized by field emission scanning electron microscopy (FESEM) to characterize the graphene’s morphology inside the PMMA. The results showed the presence of graphene in PMMA and was estimated in an amount of 0.1027% by weight in G-PMMA. The Shore hardness and Vickers microhardness values did not show statistically significant differences. Differences were observed in the compression maximum strength (129.43 MPa for PMMA and 140.23 for PMMA-G) and E values (2.01 for PMMA and 2.89 GPa for PMMA-G) as well as in the lower wear rate for the G-PMMA samples (1.93 × 10-7 for PMMA and 1.33 × 10-7 mm3/N·m) with a p < 0.005. The coefficients of friction for PMMA-G decreased from 0.4032 for PMMA to 0.4001 for PMMA-G. From the results obtained, a slight content in graphene produced a significant improvement in the mechanical properties that could be observed in the prosthesis material. Therefore, we can state that the main attraction of this material for dental prosthesis is its esthetics., Peer Reviewed, Postprint (published version)

Present commercial titanium alloy implants have an elastic modulus higher than 100 GPa, whereas that of the cortical bone is much smaller (17–28 GPa). This elastic modulus mismatch produces a stress shielding effect and the resorption of the bone surrounding the implant. In the present work, a <100> fiber texture is developed in ß type Ti-42Nb (wt%) alloy ingots generated by laser-directed energy deposition (LDED) in order to achieve anisotropic mechanical properties. In addition, we demonstrate that laser-deposited ß type Ti-42Nb alloy ingots with an intense <100> fiber texture exhibit a very low elastic modulus in the building direction (Ez < 50 GPa) and high yield (s0.2z > 700 MPa) and tensile (UTSz > 700 MPa) strengths. Laser-deposited Ti-42Nb alloy enhances the osteoinductive effect, promoting the adhesion, proliferation, and spreading of human osteoblast-like cells. Hence, we propose that laser-deposited ß type Ti-42Nb alloy is a potentially promising candidate for the manufacturing of pioneering biomedical implants with a very low elastic modulus that can suppress stress shielding., Peer Reviewed, Postprint (published version)

The Boston keratoprosthesis (BKPro) is the most widely used artificial cornea in the world for the treatment of corneal blindness in patients who are not candidates for conventional keratoplasty. Despite excellent retention rates and good vision restoration, implant viability is affected by two main complications: infection and visual loss due to retroprosthetic membrane (RPM) formation [1]. In previous work the electrodeposition technique has been shown to be efficient to functionalize titanium with silver [2]. In this work the electrodeposition technique was used to modify the BKPro titanium backplate. The aim was to confer antibacterial properties to decrease the infection rates. For this, the experimental conditions have been optimized to adjust the number of cycles, voltage, and type of applied pulse. The obtained surfaces have been characterized physiochemically by means of X-ray photoelectron spectroscopy (XPS), contact angle measurements, profilometer, and scanning electron microscopy (SEM). Adhesion and cytotoxicity were studied in human fibroblasts using the MTT assay. The effect on bacterial strains that cause ocular infections (Pseudomonas aeruginosa and Staphylococcus epidermidis) was measured by a 2-hour adhesion test. The results of SEM and XPS corroborate the presence of silver particles in the titanium samples. Cytotoxicity has not been observed. The studied treatments decrease adhesion of epidermidis and aeruginosa by 78% and almost 63%, respectively.

Passivation of titanium alloy dental meshes cleans their surface and forms a thin layer of protective oxide (TiO2) on the surface of the material to improve resistance to corrosion and prevent release of ions to the physiological environment. The most common chemical agent for the passivation process of titanium meshes is hydrochloric acid (HCl). In this work, we introduce the use of Piranha solution (H2SO4 and H2O2) as a passivating and bactericidal agent for metallic dental meshes. Meshes of grade 5 titanium alloy (Ti6Al4V) were tested after different treatments: as-received control (Ctr), passivated by HCl, and passivated by Piranha solution. Physical-chemical characterization of all treated surfaces was carried out by scanning electron microscopy (SEM), confocal microscopy and sessile drop goniometry to assess meshes’ topography, elemental composition, roughness, wettability and surface free energy, that is, relevant properties with potential effects for the biological response of the material. Moreover, open circuit potential and potentiodynamic tests were carried out to evaluate the corrosion behavior of the differently-treated meshes under physiological conditions. Ion release tests were conducted using Inductively Coupled Plasma mass spectrometry (ICP-MS). The antibacterial activity by prevention of bacterial adhesion tests on the meshes was performed for two different bacterial strains, Pseudomonas aeruginosa (Gram-) and Streptococcus sanguinis (Gram+). Additionally, a bacterial viability study was performed with the LIVE/DEAD test. We complemented the antibacterial study by counting cells attached to the surface of the meshes visualized by SEM. Our results showed that the passivation of titanium meshes with Piranha solution improved their hydrophilicity and conferred a notably higher bactericidal activity in comparison with the meshes passivated with HCl. This unique response can be attributed to differences in the obtained nanotextures of the TiO2 layer., Peer Reviewed, Postprint (published version)

Pla de Doctorat industrial de la Generalitat de Catalunya. Tesi amb diferents seccions encriptades per motius de confidencialitat, Titanium (Ti) has been used for decades for bone prostheses due to its mechanical performance and good biocompatibility. However, the stress shielding effect, as a result of the stiffness mismatch between titanium and the bone leads to bone resorption and implant failure. The use of porous titanium structures is presented as an interesting alternative material to alleviate this drawback. The conventional process of powder metallurgy (PM) offers the possibility to manufacture this kind of porous systems. Nevertheless, it is important to highlight the main challenge of this development: However, there is a constant need to manufacture flexible designs and customized implants, which is far beyond the limits of this manufacturing technology In this sense, the main additive manufacturing (AM) technologies such as electron beam melting, laser powder bed fusion or binder jetting have been postulated as promising producing techniques, even though the strong constraints associated to the powder composition, size and morphology as well as the inherent high cost of the process (raw material, equipment and post-treatments). During the development of this thesis, it was possible to work with several traumatologists and, as a result, different points of view and opinions were discussed. Some dealt topics were the need of improving both the bioactivity and antibacterial response and the currently demand of multifunctional implants with both characteristics. The functionalization by thermochemical treatments is a good and easy strategy to be applied in the industry, since not special equipment is required. In this thesis a novel direct ink writing (DIW) process was developed and optimized. The goal was to achieve the manufactured Ti porous structures through a three-step process, which consist in 3D ink injection, debinding and a sintering process as the last stage. In order to carry it out successfully, it was necessary to study all the parameters involved in each phase of the man, Durante décadas el titanio ha sido uno de los metales más utilizados en la industria biomédica debido a sus propiedades mecánicas y buena biocompatibilidad. Sin embargo, la diferencia de rigidez entre el titanio y el hueso provoca apantallamiento de tensiones (stress shielding) que se traduce en reabsorción del tejido óseo y fallo del implante. En últimos años se han estudiado diferentes vías para abordar este problema, entre las cuales se encuentra el desarrollo de métodos para la fabricación de estructuras porosas de titanio. La pulvimetalúrgia convencional (prensado y sinterizado) ofrece la oportunidad de fabricación de sistemas porosos. Sin embargo, el limitado control del tamaño y de la arquitectura, y la poca flexibilidad de diseño la hacen inviable para la fabricación de implantes a medida. Si bien en los últimos años la fabricación aditiva se postula como una alternativa prometedora, las principales tecnologías (electron beam melting, laser power bed fusion y binder jetting) están muy limitadas por las características del polvo (composición, tamaño y morfología) y el elevado coste total del proceso (materia prima, equipo y pos tratamientos). Por otra parte, durante el trascurso de la tesis, al colaborar con distintos traumatólogos y asistir a congresos de cirugía ortopédica, se evidenció la necesidad de mejorar la bioactividad y combatir la infección bacteriana en los implantes de titanio, ya que cada vez es mayor la demanda de implantes multifuncionales capaces de tener simultáneamente respuestas específicas tanto a fluidos corporales, como células y agentes patógenos. La funcionalización mediante tratamientos químicos y térmicos simples (termoquímicos) es una estrategia factible, e industrializable, ya que no requiere equipos especiales. En esta tesis se ha desarrollado y optimizado un método novedoso (100% propio), que permite fabricar estructuras porosas de titanio mediante inyección 3D de tintas con carga metálica (impresión 3D), seguido de la eliminaci, Postprint (published version)

The performance and properties of Titanium (Ti) and its alloys can be fully exploited for biomedical applications such as orthopedic and dental implants, when porous structures are used. Such Ti structures can matched the bone mechanical properties, providing a solution to the stress-shielding effect problem and facilitating implant biointegration. Powder metallurgy (PM) combined with space holder (SH) technology is an appealing process to produce porous implants. This article briefly discusses the suitability of the PM with SH technology to produce porous structures from the perspectives of both design and manufacture for the production of medical devices., Peer Reviewed, Postprint (published version)

One possibility to prevent prosthetic infections is to produce biomaterials resistant to bacterial colonization by anchoring membrane active antimicrobial peptides (AMPs) onto the implant surface. In this perspective, a deeper understanding of the mode of action of the immobilized peptides should improve the development of AMP-inspired infection-resistant biomaterials. The aim of the present study was to characterize the bactericidal mechanism against Staphylococcus epidermidis of the AMP BMAP27(1–18), immobilized on titanium disks and on a model resin support, by applying viability counts, Field Emission Scanning Electron Microscopy (FE-SEM), and a fluorescence microplate assay with a membrane potential-sensitive dye. The cytocompatibility to osteoblast-like MG-63 cells was investigated in monoculture and in co-culture with bacteria. The impact of peptide orientation was explored by using N- and C- anchored analogues. On titanium, the ~50 % drop in bacteria viability and dramatically affected morphology indicate a contact-killing action exerted by the N- and C-immobilized peptides to the same extent. As further shown by the fluorescence assay with the resin-anchored peptides, the bactericidal effect was mediated by rapid membrane perturbation, similar to free peptides. However, at peptide MBC resin equivalents the C-oriented analogue proved more effective with more than 99 % killing and maximum fluorescence increase, compared to half-maximum fluorescence with more than 90 % killing produced by the N-orientation. Confocal microscopy analyses revealed 4–5 times better MG-63 cell adhesion on peptide-functionalized titanium both in monoculture and in co-culture with bacteria, regardless of peptide orientation, thus stimulating further studies on the effects of the immobilized BMAP27(1–18) on osteoblast cells., The authors acknowledge the financial support of departmental research funds (Department of Medicine, University of Udine, Italy). The authors also gratefully thank the Generalitat de Catalunya for funding through project 2017SGR-1165 and the Ministry of Science and Innovation, Spain, for financial support through the RTI2018-098075-B-C21 project, co-funded by the EU through the European Regional Development Funds., Peer Reviewed, Postprint (author's final draft)

One of the major problems faced by metallic implants is the high probability of bacterial infections, with significant consequences for the patient. In this work, a thermochemical treatment is proposed to obtain silver-doped calcium titanate coatings on the Ti surface to improve the bioactivity of porous 3D-printed Ti structures and simultaneously provide them with antibacterial properties. A complete characterization of the new coating, the study of the ion release and the analysis of its cytotoxicity were carried out together with evaluation of the natural apatite forming in simulated body fluid (SBF). Moreover, the antibacterial properties of the coatings were assessed against Pseudomona aeruginosa and Escherichia coli as gram-negative and Staphylococcus aureus and Staphylococcus epidermidis as gram-positive bacterial strains. Ag ions were integrated into the Ca titanate layer and Ag nanoparticles were formed within the entire 3D Ti surface. Ca and Ag ions were released from both porous and solid samples into the Hanks' solution for 48 h. The treated surfaces showed no cytotoxicity and an apatite layer precipitated on the entire porous surface when the samples were immersed in SBF. The release of Ag from the surface had a strong antibacterial effect and prevented bacterial adhesion and proliferation on the surface. Moreover, the nanostructured topography of the coating resulted also in a reduction of bacterial adhesion and proliferation, even in absence of Ag. In conclusion, the cost-effective approach here reported provided protection against the most predominant bacterial colonizers to the Ti porous implants, while maintaining their bioactivity., Postprint (published version)

One of the biggest challenges in the biocompatibility of implantable metals is the prevention of the stress shielding effect, which is related to the coupling of the bone-metal mechanical properties. This stress shielding phenomenon provokes bone resorption and the consequent adverse effects on prosthesis fixation. However, it can be inhibited by adapting the stiffness of the implant material. Since the use of titanium (Ti) porous structures is a great alternative not only to inhibit this effect but also to improve the osteointegration of orthopedic and dental implants, a brief description of the techniques used for their manufacturing and a review of the current commercialized implants produced from porous Ti assemblies are compiled in this work. As powder metallurgy (PM) with space holder (SH) is a powerful technology used to produce porous Ti structures, it is here discussed its potential for the fabrication of medical devices from the perspectives of both design and manufacture. The most important parameters of the technique such as the size and shape of the initial metallic particles, the SH and binder type of materials, the compaction pressure of the green form, and in the sintering stage, the temperature, atmosphere, and time are reviewed according to the bibliography reported. Furthermore, the importance of the porosity and its types together with the influence of the mentioned parameters in the final porosity and, consequently, in the ultimate mechanical properties of the structure are discussed. Finally, a few examples of the PM-SH application for the manufacturing of orthopedic implants are presented., Peer Reviewed, Postprint (author's final draft)

Surface topography and physical-chemical properties usually play a key-role in both osseointegration improvement and bacterial colonization reduction over the surface of dental implants. The aim of this study is to compare the chemical and bacteriological behavior of two different acid passivation surface treatments on titanium c.p. grade 3 used for dental implant manufacturing. Surface roughness was evaluated using White Light Interferometry (WLI) in order to determine different roughness parameters such as average roughness (Sa), the spacing parameter (Sm) and the hybrid parameter of surface index area (SIA). Contact angle (CA) and surface free energy (SFE) were evaluated in order to establish the surface wettability of the different groups of samples. Titanium ion-release from the different samples was also been analyzed in Hank’s solution medium at 37 °C by using Inductively Coupled Plasma Mass Spectrometry (ICP-MS) at different immersion times. Bacterial viability adhesion assays were done using S. sanguinis (CECT 480, Spain) as a bacterial strain model of primary colonizer in oral biofilm formation. The bacteria attachment and morphology on Ti surfaces were determined using a live/dead staining method after 4 h of incubation and further analyzed by scanning electron microscope (SEM). Acid passivation surface treatments produced a statistically-significant (p < 0.05) roughness increase in all the evaluated parameters (Sa, Sm, SAI). The treatment with citric acid decreased the static contact angle (CA) and caused an increase in surface free energy (SFE) with a high polarization and oxidizing character. These physical-chemical surface characteristics obtained by means of citric acid passivation caused the bactericidal behavior as it has been proved in bacterial studies., Peer Reviewed, Postprint (published version)

The stress shielding, a result of the stiffness mismatch between titanium and bone, the lack of bioactivity and the infections are the main cause of the implants failure. In this work, porous titanium structures (between 50 and 70%) were produced by direct ink writing, using a new Ti ink formulation. A water and thermal treatment was optimized to ensure the complete elimination of the binder before the sintering process. The samples were sintered in high vacuum at 1150 ºC.The stiffness and compressive strength were similar to those of cancellous bone. The functionalization of the scaffold surface with a thermochemical treatment that incorporates Ga ions resulted in Ga-containing calcium titanate layer that generate homogeneous apatite layer in simulated body fluid. The Ga3+ release promote the antibacterial effect against gram positive strains. SaOS-2 cells adhered and proliferated on the Ga-doped Ti surfaces; its presence contributes to cell differentiation and increases the mineralization. © European Powder Metallurgy Association (EPMA), Postprint (published version)

The surface modification by the formation of apatitic compounds, such as hydroxyapatite, improves biological fixation implants at an early stage after implantation. The structure, which is identical to mineral content of human bone, has the potential to be osteoinductive and/or osteoconductive materials. These calcium phosphates provoke the action of the cell signals that interact with the surface after implantation in order to quickly regenerate bone in contact with dental implants with mineral coating. A new generation of calcium phosphate coatings applied on the titanium surfaces of dental implants using laser, plasma-sprayed, laser-ablation, or electrochemical deposition processes produces that response. However, these modifications produce failures and bad responses in long-term behavior. Calcium phosphates films result in heterogeneous degradation due to the lack of crystallinity of the phosphates with a fast dissolution; conversely, the film presents cracks, which produce fractures in the coating. New thermochemical treatments have been developed to obtain biomimetic surfaces with calcium phosphate compounds that overcome the aforementioned problems. Among them, the chemical modification using biomineralization treatments has been extended to other materials, including composites, bioceramics, biopolymers, peptides, organic molecules, and other metallic materials, showing the potential for growing a calcium phosphate layer under biomimetic conditions., Peer Reviewed, Postprint (published version)

In order to achieve the required properties of titanium implants, more resources and research are needed to turn into reality the dream of developing the perfect implant material. The objective of this study was to evaluate the viability of the Laser Directed Energy Deposition to produce biomedical Ti-Nb and Ti-Zr-Nb alloys from elemental powders (Ti, Nb and Zr). The Laser Directed Energy Deposition is an additive manufacturing process used to build a component by delivering energy and material simultaneously. The material is supplied in the form of particles or wire and a laser beam is employed to melt material that is selectively deposited on a specified surface, where it solidifies. Samples with different compositions are characterized to analyze their morphology, microstructure, constituent phases, mechanical properties, corrosion resistance and cytocompatibility. Laser-deposited Ti-Nb and Ti-Zr-Nb alloys show no relevant defects, such as pores or cracks. Titanium alloys with lower elastic modulus and a significantly higher hardness than Ti grade 2 were generated, therefore a better wear resistance could be expected from them. Moreover, their corrosion resistance is excellent due to the formation of a stable passive protective oxide film on the surface of the material; in addition, they also possess outstanding cytocompatibility., Peer Reviewed, Postprint (published version)

Gallium (Ga) has been recently proposed as a novel therapeutic agent, since it promotes bone formation and exhibits antibacterial properties. This work focuses on the optimization of a thermochemical treatment that incorporates Ga ions by the addition of the body-friendly Ga nitrate approved by the Food and Drug Administration. The objective was to simultaneously provide the inner and the outer surfaces of porous-titanium surfaces obtained by 3D-printing with bioactivity and antibacterial properties. The apatite-forming ability of the coating, as well as the antibacterial activity and SaOS-2 cell adhesion, proliferation, differentiation and mineralization were evaluated and compared with untreated Ti surfaces. The characterization of the surfaces revealed the presence of a Ga-containing calcium titanate layer, which was non cytotoxic and in simulated body fluid produced a homogeneous apatite coating well adhered to the substrate. The formation of this apatite layer was accelerated with increasing Ga amounts present on the surface, resulting also in an increase in thickness. An initial quick release of Ga ion promoted the antibacterial effect against gram positive strains, especially for Pseudomonas aeruginosa, one of the most frequent resistant pathogens in nosocomial infections. SaOS-2 cells adhered and proliferated on the Ga-doped Ti surfaces, its presence contributed to cell differentiation and to considerably increase the mineralization levels. Thus, the developed multifunctional coatings could provide bioactivity to the porous Ti implants while protecting them from the most frequent gram-negative pathogens., Peer Reviewed, Postprint (author's final draft)

Although ceramic-on-ceramic (CoC) bearings have been shown to produce the smallest amount of wear volume in vitro as well as in vivo studies when used for total hip arthroplasties (THA), concerns about the failure of these bearing surfaces persist due to early failures observed after short postoperative time. In this study, an exhaustive analysis of the early failure occurred on the new generation of ceramic bearings, consisting of a composite alumina matrix-based material reinforced with yttria-stabilized tetragonal zirconia (Y-TZP) particles, chromium dioxide, and strontium crystals, was performed. For this study, 118 CoC bearings from 117 patients were revised. This article describes a group of mechanical failure CoC-bearing BIOLOX THA hip prosthesis patients without trauma history. The retrieved samples were observed under scanning electron microscopy (SEM), composition was analyzed with energy dispersive X-ray spectroscopy (EDX), and damaged surfaces were analyzed by grazing-incidence X-ray diffraction (GI-XRD) and white light interferometry. In the short term, CoC articulations provided similar mechanical behavior and functional outcome to those in XLPE cases. However, 5% more early mechanical failures cases were observed for the ceramic components. Although the fracture rate of third generation CoC couples is low, the present study shows the need to further improve the third generation of CoC-bearing couples for THA. Despite the improved wear compared to other materials, stress concentrators are sources of initial crack propagation, such as those found in the bore-trunnion areas. Moreover, in view of the evidence observed in this study, the chipping observed was due to the presence of monoclinic phase of the Y-TZP instead of tetragonal, which presents better mechanical properties. The results showed that total safety after receiving a THA is still a goal to be pursued., Peer Reviewed, Postprint (published version)

Titanium (Ti) and Ti alloys have been used for decades for bone prostheses due to its mechanical reliability and good biocompatibility. However, the high stiffness of Ti implants and the lack of bioactivity are pending issues that should be improved to minimize implant failure. The stress shielding e ect, a result of the stiffness mismatch between titanium and bone, can be reduced by introducing a tailored structural porosity in the implant. In this work, porous titanium structures were produced by direct ink writing (DIW), using a new Ti ink formulation containing a thermosensitive hydrogel. A thermal treatment was optimized to ensure the complete elimination of the binder before the sintering process, in order to avoid contamination of the titanium structures. The samples were sintered in argon atmosphere at 1200 ºC, 1300 ºC or 1400 ºC, resulting in total porosities ranging between 72.3% and 77.7%. A correlation was found between the total porosity and the elastic modulus of the sca olds. The stiffness and yield strength were similar to those of cancellous bone. The functionalization of the sca old surface with a cell adhesion fibronectin recombinant fragment resulted in enhanced adhesion and spreading of osteoblastic-like cells, together with increased alkaline phosphatase expression and mineralization., Peer Reviewed, Postprint (published version)

Through the years, the medicine has been modernized to reach today a complex science complying diagnosis, treatments and prevention of illness. This project is focused on the orthopedic surgery and more particularly on medical implants. Medical implants are medical devices which are incorporated in the human body in order to support or replace a missing biological structure. The human body is fragile, and it is necessary to pay attention to the biocompatibility of the medical implants in order to avoid contamination or poisoning. This is why medical implants are mostly made, nowadays, in biocompatible materials such as ceramics, polymers or specific metal alloys as titanium alloys or Nickel alloys. These materials present good corrosion resistance or even are completely inert towards the human body. This project will be focused on titanium orthopedic implants. Titanium and its alloys present interesting properties as a high strength to density ratio, a good corrosion resistance due to the combination of the different surface-formed oxide layers and offer an excellent biocompatibility. This unique combination of properties makes them ideal materials for medical implants. However, titanium implants present issues regarding long-term performances due to a mismatch in mechanical properties between the implant and natural bone. These differences can enhance stress shielding effect. To avoid this mismatch, the solution is to adjust the mechanical properties of titanium so that they are as similar as possible to those of bone. This is achieved by the introduction of a sufficient amount of porosity. Indeed, by controlling the porosity, it is possible to tailor the mechanical properties of a solid material. In order to confer a superior bone-bonding property to titanium implants, attempts have been made to coat their surfaces with a thin layer of bone-bonding ceramic, such assodium titanate, by the means of chemical and heat treatments To avoid infection, caused by the intro, Incoming

Bacterial infection of orthopaedic implants, often caused by Staphylococcus species, may ultimately lead to implant failure. The development of infection-resistant, osteoblast-compatible biomaterials could represent an effective strategy to prevent bacterial colonization of implants, reducing the need for antibiotics. In this study, the widely used biomaterial titanium was functionalized with BMAP27(1–18), an a-helical cathelicidin antimicrobial peptide that retains potent staphylocidal activity when immobilized on agarose beads. A derivative bearing a short spacer with a free thiol at the N-terminus was coupled to silanized titanium disks via thiol-maleimide chemistry. Tethering was successful, as assessed by Contact angle, Quartz Crystal Microbalance with Dissipation monitoring (QCM-D), and X-ray Photoelectron Spectroscopy (XPS), with an average surface mass density of 456¿ng/cm2 and a layer thickness of 3¿nm. The functionalized titanium displayed antimicrobial properties against a reference strain of Staphylococcus epidermidis with well-known biofilm forming capability. Reduction of bacterial counts and morphological alterations of adhering bacteria, upon 2¿h incubation, indicate a rapid contact-killing effect. The immobilized peptide was not toxic to osteoblasts, which adhered and spread better on functionalized titanium when co-cultured with bacteria, compared to non-coated surfaces. Results suggest that functionalization of titanium with BMAP27(1–18) could be promising for prevention of bacterial colonization in bone graft applications., Peer Reviewed, Postprint (author's final draft)

Sixty-four fractured commercially pure titanium (cp-Ti) narrow dental implants (NDIs) with similar macrogeometry and connection designs were studied after different implantation times in humans in order to determine their reliability and to evaluate the causes of the fracture. These NDIs were compared with other similar implants, made with alloyed titanium with 15% Zr and with 12% strained titanium. Original implants were tested under static and fatigue conditions, simulating the tri-axial loads in the mouth by means of a Bionix hydraulic test machine. Fractography was studied using field-emission scanning electron microscopy (FSEM). The results showed that cp-Ti NDI exhibits low strength for mechanical cycling, and the alloyed Ti and strained titanium increase the mechanical strength, guaranteeing long term mechanical behavior. NDIs fractured due to fatigue, and, in some cases, the presence of cracks in the original NDIs quickly led to fracture. These cracks were attributed to plastic deformation during machining were found to be exacerbated due to acid etching in the passivation process. All cases of fracture were cp-Ti dental implants due to the low fatigue limit. The results show that, when titanium is alloyed or cold-worked, the fatigue limit is higher than cp-Ti. This in vitro research will help clinicians to select a better NDI system for safer treatment., Peer Reviewed, Postprint (published version)

Synergizing integrin and cell-membrane heparan sulfate proteoglycan signaling on biomaterials through peptidic sequences is known to have beneficial effects in the attachment and behavior of osteoblasts; however, controlling the exact amount and ratio of peptides tethered on a surface is challenging. Here, we present a dual molecular-based biointerface combining integrin (RGD) and heparin (KRSR)-binding peptides in a chemically controlled fashion. To this end, a tailor-made synthetic platform (PLATF) was designed and synthesized by solid-phase methodologies. The PLATF and the control linear peptides (RGD or KRSR) were covalently bound to titanium via silanization. Physicochemical characterization by means of contact angle, Raman spectroscopy and XPS proved the successful and stable grafting of the molecules. The biological potential of the biointerfaces was measured with osteoblastic (Saos-2) cells both at short and long incubation periods. Biomolecule grafting (either the PLATF, RGD or KRSR) statistically improved (p < 0.05) cell attachment, spreading, proliferation and mineralization, compared to control titanium. Moreover, the molecular PLATF biointerface synergistically enhanced mineralization (p < 0.05) of Saos-2 cells compared to RGD or KRSR alone. These results indicate that dual-function coatings may serve to improve the bioactivity of medical implants by mimicking synergistic receptor binding., Postprint (published version)

Las enfermedades bucodentales, como la caries dental o la periodontitis, son un problema de salud de alcance mundial. Además, una población cada vez más envejecida, un incremento de la concienciación sobre la importancia de la salud oral y un aumento de los estándares estéticos, han provocado un aumento en el número de implantes dentales que se colocan al año. Este hecho, junto con la posibilidad de fallo de los implantes dentales a largo plazo, inducen la necesidad de crear nuevas estrategias que permitan aumentar el éxito de los implantes dentales. En este sentido, con el presente proyecto se ha intentado crear una estrategia que permita aumentar la osteointegración de los implantes. Para ello se ha desarrollado un tratamiento de foto-activación superficial mediante luz ultravioleta que permite aumentar la mojabilidad del implante para estimular la respuesta celular cuando se implanta. Este tratamiento se ha desarrollado con la intención de realizarlo en la misma clínica del implantólogo, de este modo el propio cirujano podría seleccionar el implante óptimo y aplicarle el tratamiento justo antes de implantarlo. Para ello, se ha realizado también una selección preliminar de materiales que permitiría la aplicación del tratamiento a través suyo y que podría actuar como envase del implante. Los resultados sugieren que el tratamiento de foto-activación aumenta considerablemente la mojabilidad sobre el titanio y aumenta la adsorción de proteínas en su superficie. Este hecho favorecería la cascada de eventos que ocurre tras la implantación. No obstante, las muestras tratadas (con texturizarían superficial) no presentan diferencias significativas en los resultados celulares. Por otro lado, la selección de materiales realizada indica que es posible encontrar algún material vítreo técnico que permita la aplicación del tratamiento in situ.

El titani és un biomaterial àmpliament usat en biomedicina gràcies a les seves propietats, les quals el converteixen en un material adient per la fabricació d’implants ortopèdics i dentals. De totes maneres, encara presenta inconvenients com l’apantallament de tensions, una difícil fixació a l’os (osteointegració) i les infeccions bacterianes. L’objectiu d’aquest treball és millorar les propietats del titani, utilitzant geometries tridimensionals i recobriments que ajudin a reduir l’absorció de l’os deguda a l’apantallament de tensions, afavorir l’osteointegració i presentar un efecte antimicrobià. Es proposa treballar amb estructures poroses de titani, confeccionades per mitjà de tècniques d’impressió 3D, alhora que amb les estructures llises que ja han estat motiu d’estudi en projectes anteriors. Es proposa el recobriment del material amb una plataforma peptídica que contingui el motiu d’adhesió cel·lular RGD i un pèptid antibacterià derivat de la lactoferrina. Les mostres de titani llis i poroses són funcionalitzades usant diferents concentracions d’aquesta biomolècula. Per demostrar la presència d’aquesta plataforma en els nostres materials, es presenten tres mètodes de caracterització: la microscòpia de fluorescència confocal, espectroscòpia Raman i espectroscòpia de fotoelectrons emesos per raig X (XPS). Finalment, es prova l’eficàcia bactericida de la plataforma mitjançant assajos amb diferents soques bacterianes (S. aureus i E. coli), els quals es duen a terme per mitjà de la tècnica Live/Dead. Els resultats demostren que la tècnica de funcionalització emprada permet ancorar de manera exitosa la plataforma a les superfícies de titani, tant 2D com 3D. Els resultats dels estudis d’adhesió bacteriana corroboren el potencial bactericida de la molècula tant per soques Gram positiu com negatiu.

Installing bioactivity on metallic biomaterials by mimicking the extracellular matrix (ECM) is crucial for stimulating specific cellular responses to ultimately promote tissue regeneration. Fibronectin is an ECM protein commonly used for biomaterial functionalization. The use of fibronectin recombinant fragments is an attractive alternate to the use of full-length fibronectin because of the relatively low cost and facility of purification. However, it is necessary to combine more than one fragment, for example, the cell attachment site and the heparin binding II (HBII), either mixed or in one molecule, to obtain complete activity. In the present study, we proposed to install adhesion capacity to the HBII fragment by an RGD gain-of-function DNA mutation, retaining its cell differentiation capacity and thereby producing a small and very active protein fragment. The novel molecule, covalently immobilized onto titanium surfaces, maintained the growth factor-binding capacity and stimulated cell spreading, osteoblastic cell differentiation, and mineralization of human mesenchymal stem cells compared to the HBII native protein. These results highlight the potential capacity of gain-of-function DNA mutations in the design of novel molecules for the improvement of osseointegration properties of metallic implant surfaces., Peer Reviewed, Postprint (author's final draft)

Metallic implants have some limitations related to bioactivity and bacteria colonization leading to infections. In this regard, calcium phosphate coatings can be used as carrier for drug delivery in order to improve the mentioned drawbacks. The present work proposes the introduction of an antibacterial agent in the course of a pulsed and reverse pulsed electrodeposition. Calcium phosphate coatings were prepared in 30¿min using different pulse waveforms (unipolar-bipolar), current densities (2–5¿mA/cm2) and temperatures (40–60¿°C). Mechanical stability of the as-coated surfaces was studied in order to select the optimal electrodeposition conditions. Subsequently, selected coatings were loaded with an antiseptic agent, chlorhexidine digluconate (CHX), via a single-step co-deposition procedure. CHX concentration added to the electrolyte was adjusted to 3¿mM based on the antibacterial efficacy of the loaded coatings evaluated in vitro with Staphylococcus aureus and Escherichia coli bacteria strains. Whereas the same chlorhexidine concentration was added to the electrolyte, results showed that the amount of CHX loaded was different for each condition while release kinetics was maintained. The results of this work demonstrate that a pulsed co-deposition strategy has great potential to modulate local delivery of antibacterial agents such as chlorhexidine digluconate, which may prevent early phase infections of metallic implants after insertion., Postprint (author's final draft)

In this communication we report that anchoring avß3 or a5ß1 integrin-selective RGD peptidomimetics to titanium efficiently tunes mesenchymal stem cell response in vitro and bone growth in rat calvarial defects. Our results demonstrate that this molecular chemistry-derived approach could be successful to engineer instructive coatings for orthopedic applications., Peer Reviewed, Postprint (author's final draft)

Biomaterial-associated infections (BAI) are the major cause of failure of indwelling medical devices. The risk of BAI can end dramatically in the surgical removal of the affected device. Therefore, a major effort must be undertaken to guarantee the permanence of the implant. In this regard, we have developed antimicrobial coatings for tantalum (Ta) implants, using polyhydroxyalkanoates (PHAs) as matrices for carrying an active principle. The dip-coating technique was successfully used for covering solid Ta discs. An original PHA emulsion flow process was developed for the coating of porous Ta structures, specially for the inner surfaces. The complete characterization of the biopolymer coatings, their antibacterial properties, toxicity and biointegration were analyzed. Thus, non-toxic, well-biointegrated homogeneous biopolymer coatings were attained, which showed antibacterial properties. By using biodegradable PHAs, the resulting drug delivery system assured the protection of Ta against bacterial infections for a period of time., Peer Reviewed, Postprint (author's final draft)

El campo de los biomateriales ha crecido sustancialmente en los últimos años desde que en 1969 se realizase la primera conferencia sobre biomateriales en la universidad de Clemson, Carolina del Sur. Se definió entonces biomaterial como cualquier material natural o artificial utilizado para crear soportes o implantes que permitan reemplazar estructuras biológicas perdidas o enfermas, restaurando así su forma y función [01]. Para entender el gran foco de atención que ha recibido el campo de los biomateriales es necesario comprender las causas que han llevado a la comunidad científica a la necesidad de desarrollar nuevos materiales para cumplir con las necesidades biológicas que este nuevo campo requiere. Así, según datos de la American Academy of Othopedics Surgeons se estima que un 90% de la población mayor de 40 años sufre enfermedades degenerativas asociadas con la perdida de funcionalidad en estructuras biológicas tales como huesos, órganos o tejidos. Si a esto se le suma que, según las previsiones de las naciones unidas [02], la población en Europa mayor de 60 años se estima duplicará su número en 2050 pasando de 962 millones en 2017 a más de 2100 millones en 2050, se espera que en los próximos años más de un 25% de la población requiera de soluciones contra los problemas degenerativos relativos al cuerpo. Así, si la atención se centra en el campo de la ortopedia, donde se ha producido un mayor impacto en el número de enfermedades y problemas degenerativos, se calcula que en 2030 el número total de reemplazos de cadera crecerá un 174%, alcanzando la alarmante cifra de 572.000 operaciones por año, mientras que la demanda en reemplazos parciales y totales de rodilla crecerá un 673%, con un total de 3,48 millones de procedimientos esperados [02]. Estas enfermedades degenerativas relativas a los huesos suelen ser debido a una carga excesiva o una ausencia del proceso biológico de regeneración y llevan, normalmente, a una degradación de las propiedades mecánicas de lo

A relevant aspect in the biomedical field is the research for optimizing the bone-implant coupling in order to avoid the stress-shielding effect. Bone requires a mechanical stimulus for growth; hence, in a bone-implant coupling, it is essential to use materials with stiffness properties similar to bone for improving the load-transfer and favoring bone healing and remodeling. One alternative method of lowering the elastic is developing porous materials (metallic foams) that have demonstrated their potential to allow rapid bone ingrowth. Another important aspect of the use of biomaterials is linked with medical device-related infections. These infections may cause an implant failure, with the corresponding implant revision or removal process and the associatedpatient’s pain and costs. Recently, it has been shown that functional metal ions such as Ca, Sr, Mg and Ag can be incorporated into the Ti surface by modifying the conditions or the thermochemical treatment [35]. In this regard, silver (Ag)-based compounds have been used in this project to obtain porous titanium with antibacterial properties. AMES, a company in automotive is willing to expend its market to the biomedical domain. They want to launch their first functionalized prosthesis in titanium 3D printed and industrialize it. The bioactivation of the titanium process must be effective, cheap and as short as possible. There are many processes to bioactivate the titaniumlike the apatite plasma coatingor calcium phosphate deposition by sputtering, butthethermochemical treatment can homogeneously cover complex shapes so is the most adapted for industrializationof porous prostheses.This thermochemical process chosen by AMESis composed of 2 steps after cleaning the sample, attack the samplewith a 5M NaOH solution at 60°C for 24h and finally a 600°C heat treatment for 1 hour. The first step is the most time consumer,therefore,the first aim was to optimize the time process of alkaline etching. Three timeshave beenexp, Incoming

The load transfer from metallic prosthesis to tissue plays an important role in the success of a designed device. From a mechanical behavior point of view, the load transfer will be favored when the elastic modulus between the metallic implant and the bone tissue are similar. Titanium and Ti-6Al-4V are the most commonly used metals and alloys in the field of dental implants, although they present high elastic moduli and hence trigger bone resorption. We propose the use of low-modulus ß-type titanium alloys that can improve the growth of new bone surrounding the implant. We designed dental implants with identical morphology and micro-roughness composed of: Ti-15Zr, Ti-19.1Nb-8.8Zr, Ti-41.2Nb-6.1Zr, and Ti-25Hf-25Ta. The commercially pure Ti cp and Ti-6Al-4V were used as control samples. The alloys were initially mechanically characterized with a tensile test using a universal testing machine. The results showed the lowest elastic modulus for the Ti-25Hf-25Ta alloy. We implanted a total of six implants in the mandible (3) and maxilla (3) for each titanium alloy in six minipigs and evaluated their bone index contact (i.e., the percentage of new bone in contact with the metal—BIC%) after 3 and 6 weeks of implantation. The results showed higher BIC% for the dental implants with lowest elastic modulus, showing the importance of decreasing the elastic modulus of alloys for the successful osseointegration of dental implants., Postprint (published version)

En el present Treball de Final de Grau es fa un estudi d’una possible tècnica de millora de la integració dels implants dentals de titani amb el teixit cel·lular, i tracta específicament l’opció de crear una superfície de titani el més antibacteriana possible. Mitjançant un atac de caràcter àcid, la superfície del titani queda modificada creant una nanoestructura que segons l’article Surface Nanoporosity has a greater influence on osteogènic and bacterial cell adhesion than crystallinity and wettability [1] esdevé antibacteriana. Així doncs, l’objectiu del projecte és replicar aquesta superfície que per si sola és antibacteriana i a més a més, tal com diu l’altre article Anhydride-functional silane immobilized onto titanium surfaces induces osteoblasts cell differentiation and reduces bacterial adhesion and biofilm formation [2], afegir un silà anomenat TESPSA que també té un efecte antibacterià; de forma que amb la combinació d’ambdós efectes, poder obtenir una superfície del titani idònia, pel seu caràcter antibacterià, pels implants dentals. Com a objectiu extra del projecte, s’intenta, també, optimitzar el temps de producció de la superfície de titani creada segons el primer dels articles [1]. Per a dur a terme aquest projecte cal un treball de laboratori que consta en la preparació de mostres de titani llises, fer sobre elles un atac àcid amb una solució anomenada Piranha, silanitzar les mostres amb TESPSA, fer una caracterització de la superfície atacada i finalment, realitzar assaigs amb bacteris amb l’objectiu de verificar si es tracta d’una superfície antibacteriana o no. A l’hora de procedir amb aquest treball de laboratori, s’ha pogut fer tot el proposat, tot i que els resultats d’alguns assajos no han estat els esperats. L’intent de rèplica de la superfície del titani de l’article de Rodriguez-Contreras, et al. 2018 [1], no ha resultat en la superfície antibacteriana esperada. De totes formes, s’ha procedit amb el projecte usant una variant de superfície

Currently, implant and prosthetic infections are a serious problem, due to the increased use of these prostheses and the presence of bacteria multiresistant to antibiotics. These infections originate, in most cases, from planktonic bacteria. A possible strategy to avoid infections is to develop anti-fouling surfaces that prevent bacterial adhesion. Another strategy focuses on conferring bactericidal properties to the surfaces of the implants with the use of antimicrobial peptides. In both cases, it is necessary to maintain the excellent union to the tissues that titanium presents. The ideal surface for prostheses would combine antifouling, bactericidal and osseointegration properties, achieving an excellent synergic effect on the surfaces of the implants, improving their stability and functionality. To achieve this goal it is necessary to solve a critical point, which is to functionalize the anti-fouling layer with other biomolecules that can improve its properties. The objective of the present work is to deposit an anti-fouling layer on a metallic biomaterial, which can be further functionalized with other biomolecules. Titanium has been coated with functionalized polyethylene glycol (PEG) to which the Arg-Gly-Asp (RGD) peptide sequence has been attached. The treated titanium surfaces have shown an excellent combination of antifouling properties and good cellular response., Actualmente las infecciones de implantes y prótesis son un problema grave, debido al incremento de uso de dichas prótesis y a la cada vez mayor presencia de bacterias resistentes a los antibióticos. Estas infecciones tienen su origen, en la mayoría de casos, en bacterias planctónicas. Una posible estrategia para evitar las infecciones es desarrollar superficies anti-fouling que eviten la adhesión bacteriana. Otra estrategia se centra en conferir propiedades bactericidas a las superficies de los implantes en el uso de péptidos antimicrobianos. En ambos casos, es necesario mantener la excelente unión a los tejidos que presenta el titanio.La superficie ideal para prótesis combinaría los efectos anti-fouling, bactericida y osteointegrativo, logrando un excelente efecto sinérgico en las superficies de los implantes, mejorando su estabilidad y funcionalidad. Para conseguir este objetivo es necesario solventar un punto crítico, que es funcionalizar la capa anti-fouling con otras biomoléculas que permitan dotarla de las propiedades mencionadas.El objetivo del presente trabajo es depositar una capa anti-fouling sobre un biomaterial metálico con un grupo funcional que permita enlazar a la superficie tratada otras biomoléculas. Se ha conseguido depositar una capa de (poli)etilenglicol (PEG) funcionalizado sobre titanio, al cual se ha unido la secuencia tripeptídica Arg-Gly-Asp (RGD). Las superficies tratadas han mostrado una excelente combinación de propiedades anti-fouling y de buena respuesta celular.

Peri-implantitis is an infectious disease that affects the supporting soft and hard tissues around dental implants and its prevalence is increasing considerably. The development of antibacterial strategies, such as titanium antibacterial-coated surfaces, may be a promising strategy to prevent the onset and progression of peri-implantitis. The aim of this study was to quantify the biofilm adhesion and bacterial cell viability over titanium disc with or without antibacterial surface treatment. Five bacterial strains were used to develop a multispecies oral biofilm. The selected species represent initial (Streptococcus oralis and Actinomyces viscosus), early (Veillonella parvula), secondary (Fusobacterium nucleatum) and late (Porphyromonas gingivalis) colonizers. Bacteria were sequentially inoculated over seven different types of titanium surfaces, combining different roughness level and antibacterial coatings: silver nanoparticles and TESPSA silanization. Biofilm formation, cellular viability and bacterial quantification over each surface were analyzed using scanning electron microscopy, confocal microscopy and real time PCR. Biofilm formation over titanium surfaces with different bacterial morphologies could be observed. TESPSA was able to significantly reduce the cellular viability when compared to all the surfaces (p¿<¿0.05). Silver deposition on titanium surface did not show improved results in terms of biofilm adhesion and cellular viability when compared to its corresponding non-coated surface. The total amount of bacterial biofilm did not significantly differ between groups (p¿>¿0.05). TESPSA was able to reduce biofilm adhesion and cellular viability. However, silver deposition on titanium surface seemed not to confer these antibacterial properties., Peer Reviewed, Postprint (published version)

This project is a part of the development of biomaterials for bone tissue engineering for type 2 diabetic patients. The latters show a higher rejection implant rate than healthy people. When people are affected by type 2 diabetes they develop insulin resistance and the glucose accumulates in blood. Hyperglycemia leads to the ROS (reactive oxygen species) production. The ROS takes part of an equilibrium (redox biology). They are used by cells in several mechanisms such as signal transduction, cellular proliferation or differentiation and development. However if they are overproduced, they become cytotoxic and leads to oxidative stress. ROS have an impact on bone remodeling and enhance the resorption of bones. In the case of implant, a local treatment of ROS is needed to help the bone to form around the implant. To counterbalance the oxidative stress from the ROS, the nifedipine will be used for its anti-oxidative properties. But this drug is light sensitive and poorly soluble in water and it affects its bioavailability. To protect it and have a local treatment, silica mesoporous nanoparticles are used. Thanks to their high surface area and their high pore volume, it is possible to load a large quantity of drug inside the pores via adsorption. And the nanoparticles can bring a protection to the drug. The aims of the project is to chose the best way to load nanoparticles among different methods and to choose a release method between three ones. The first step of this project has been the synthesis of nanoparticles. The technique used is a sol-gel process where silica is obtained by the hydrolysis of TEOS on CTAB in a basic medium. A co-condensation was driven with APTES, the functionalization. The second step was the loading of the nanoparticles with nifedipine. Four methods have been studied. The characterization has been done by Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). The FTIR gives evidence of the presence of nifedipine a

Bones can suffer from damages due to ageing or traumatisms like fractures. When they are too damaged or if the fracture is too important, bones often need an exterior help to recover: the implants. The ideal implant maintains bone parts together and could promote bone regeneration and osseointegration. However, after placing the implant into the body, bone healing and regeneration sometimes don’t work through properly. Indeed, the current bone implants sometimes lead to failure especially with patients suffering from diabetes mellitus (DM). In fact, it has been shown that DM is linked to the phenomenon called oxidative stress. The latter induces an accumulation of reactive oxygen species (ROS) which can cause dysfunction of the bone regenerating cells, the osteoblasts. Titanium and its alloys are a well-known for their performances as biomaterials. The idea to prevent the implantation failure is to develop new functionalized implants. These implants must act like drug-carrier and be able to release the appropriate amount of drug locally. Many studies proposed different coatings for titanium that can be loaded with active principle. Among such coatings, the mesoporous silica nanoparticles (MSN) may be an efficient drug-carrying coating for titanium implants. The other coating techniques that have been studied involved weak bonds. However, the ideal coating needs to be bound strongly enough to remain stable on the titanium surface. Thus, the coating technique is a crucial parameter to obtain the ideal MSN coating. This project aimed to develop MSN coating on titanium substrate. The process chosen for such coating was based on the silanization reaction. Silanized titanium substrates would react with functionalized MSN. This kind of reaction would induce the covalent bonding that is required between the nanoparticles and the titanium substrate to provide the right mechanical strength for the coating. In this study, titanium substrate silanization process has been review

Postprint (published version)

Strategies to inhibit initial bacterial adhesion are extremely important to prevent infection on biomaterial surfaces. However, the simultaneous attraction of desired eukaryotic cells remains a challenge for successful biomaterial-host tissue integration. Here we describe a method for the development of a trifunctional coating that repels contaminating bacteria, kills those that adhere, and promotes osteoblast adhesion. To this end, titanium surfaces were functionalized by electrodeposition of an antifouling polyethylene glycol (PEG) layer and subsequent binding of a peptidic platform with cell-adhesive and bactericidal properties. The physicochemical characterization of the samples via SEM, contact angle, FTIR and XPS analysis verified the successful binding of the PEG layer and the biomolecules, without altering the morphology and topography of the samples. PEG coatings inhibited protein adsorption and osteoblast-like (SaOS-2) attachment; however, the presence of cell adhesive domains rescued osteoblast adhesion, yielding higher values of cell attachment and spreading compared to controls (p < 0.05). Finally, the antibacterial potential of the coating was measured by live/dead assays and SEM using S. sanguinis as a model of early colonizer in oral biofilms. The presence of PEG layers significantly reduced bacterial attachment on the surfaces (p < 0.05). This antibacterial potential was further increased by the bactericidal peptide, yielding values of bacterial adhesion below 0.2% (p < 0.05). The balance between the risk of infection and the optimal osteointegration of a biomaterial is often described as “the race for the surface”, in which contaminating bacteria and host tissue cells compete to colonize the implant. In the present work, we have developed a multifunctional coating for a titanium surface that promotes the attachment and spreading of osteoblasts, while very efficiently inhibits bacterial colonization, thus holding promise for application in bone repl, Peer Reviewed, Postprint (author's final draft)