Fabrication and bioactivity evaluation of porous anodised TiO2 films in vitro

Mesoscopic Model for Reversible Adsorption Stage of Albumin and Fibrinogen on TiO2 Surface

The competitive behavior of proteins in the reversible adsorption stage plays a crucial role in determining the composition of the protein layer and the subsequent biological responses to the biomaterial. However, such competitive adsorption is a mesoscopic process at physiological protein concentration, and neither a macroscopic experiment nor microscopic MD (molecular dynamics) simulation is suitable to clarify it. Here, we proposed a mesoscopic DPD (dissipative particle dynamics) model to illustrate the competitive process of albumin and fibrinogen on TiO2 surface with its parameters deduced from our previous MD simulation, and proved the model well retained the diffusion and adsorption properties of proteins in the competitive adsorption on the plane surface. We then applied the model to the competitive adsorption on the surfaces with different nanostructures and observed that when the nanostructure size is much larger than that of protein, the increase in surface area is the main influencing factor; when the nanostructure size is close to that of protein, the coordination between the nanostructure and the size and shape of protein significantly affects the competitive adsorption process. The model has revealed many mechanical phenomena observed in previous experimental studies and has the potential to contribute to the development of high-performance biomaterials.

Effect of Low-Temperature Oxygen Plasma Treatment of Titanium Alloy Surface on Tannic Acid Coating Deposition

In this study, the effect of low-temperature oxygen plasma treatment with various powers of a titanium alloy surface on the structural and morphological properties of a substrate and the deposition of a tannic acid coating was investigated. The surface characteristics of the titanium alloy were evaluated by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), atomic force microscopy (AFM), and contact angle measurements. Following this, the tannic acid coatings were deposited on the titanium alloy substrates and the structural and morphological properties of the tannic acid coatings deposited were subject to characterization by XPS, SEM, and spectroscopic ellipsometry (SE) measurements. The results show that the low-temperature oxygen plasma treatment of titanium alloys leads to the formation of titanium dioxides that contain -OH groups on the surface being accompanied by a reduction in carbon, which imparts hydrophilicity to the titanium substrate, and the effect increases with the applied plasma power. The performed titanium alloy substrate modification translates into the quality of the deposited tannic acid coating standing out by higher uniformity of the coating, lower number of defects indicating delamination or incomplete bonding of the coating with the substrate, lower number of cracks, thinner cracks, and higher thickness of the tannic acid coatings compared to the non-treated titanium alloy substrate. A similar effect is observed as the applied plasma power increases.

Surface Modification and Functionalities for Titanium Dental Implants

Dental implants have become the mainstream strategy for oral restoration, and implant materials are the most important research hot spot in this field. So far, Ti implants dominate all kinds of implants. The surface properties of the Ti implant play decisive roles in osseointegration and antibacterial performance. Surface modifications can significantly change the surface micro/nanotopography and composition of Ti implants, which will effectively improve their hydrophilicity, mechanical properties, osseointegration performance, antibacterial performance, etc. These optimizations will thus improve implant success and service life. In this paper, the latest surface modification techniques of Ti dental implants are systematically and comprehensively reviewed. The various biomedical functionalities of surface modifications are discussed in-depth. Finally, a profound comment on the challenges and opportunities of this frontier is proposed, and the most promising directions for the future were explored.

Titanium and Protein Adsorption: An Overview of Mechanisms and Effects of Surface Features

Titanium and its alloys, specially Ti6Al4V, are among the most employed materials in orthopedic and dental implants. Cells response and osseointegration of implant devices are strongly dependent on the body-biomaterial interface zone. This interface is mainly defined by proteins: They adsorb immediately after implantation from blood and biological fluids, forming a layer on implant surfaces. Therefore, it is of utmost importance to understand which features of biomaterials surfaces influence formation of the protein layer and how to guide it. In this paper, relevant literature of the last 15 years about protein adsorption on titanium-based materials is reviewed. How the surface characteristics affect protein adsorption is investigated, aiming to provide an as comprehensive a picture as possible of adsorption mechanisms and type of chemical bonding with the surface, as well as of the characterization techniques effectively applied to model and real implant surfaces. Surface free energy, charge, microroughness, and hydroxylation degree have been found to be the main surface parameters to affect the amount of adsorbed proteins. On the other hand, the conformation of adsorbed proteins is mainly dictated by the protein structure, surface topography at the nano-scale, and exposed functional groups. Protein adsorption on titanium surfaces still needs further clarification, in particular concerning adsorption from complex protein solutions. In addition, characterization techniques to investigate and compare the different aspects of protein adsorption on different surfaces (in terms of roughness and chemistry) shall be developed.

Review of titanium surface modification techniques and coatings for antibacterial applications

Implanted biomaterials play a key role in the current success of orthopedic and dental procedures. Pure titanium and its alloys are the most commonly used materials for permanent implants in contact with bone. However, implant-related infections remain among the leading reasons for failure. The most critical pathogenic event in the development of infection on biomaterials is biofilm formation, which starts immediately after bacterial adhesion. In the last decade, numerous studies reported the ability of titanium surface modifications and coatings to minimize bacterial adhesion, inhibit biofilm formation and provide effective bacterial killing to protect implanted biomaterials. In the present review, the different strategies to prevent infection onto titanium surfaces are reported: surface modification and coatings by antibiotics, antimicrobial peptides, inorganic antibacterial metal elements and antibacterial polymers. STATEMENT OF SIGNIFICANCE: Implanted biomaterials play a key role in the current success of orthopedic and dental procedures. Pure titanium and its alloys are the most commonly used materials for permanent implants in contact with bone. Microbial infection is one of the main causes of implant failure. Currently, the global infection risk is 2-5% in orthopedic surgery. Numerous solutions exist to render titanium surfaces antibacterial. The LBPS team is an expert on the functionalization of titanium surfaces by using bioactive polymers to improve the biologiocal response. In this review, the different strategies to prevent infection are reported onto titanium and titanium alloy surfaces such as surface modification by antibiotics, antimicrobial peptides, inorganic antibacterial metal elements and antibacterial polymers.

Polydopamine deposition with anodic oxidation for better connective tissue attachment to transmucosal implants

BACKGROUND AND OBJECTIVE

Nowadays, most designs for the transmucosal surface of implants are machined-smooth. However, connective tissue adhered to the smooth surface of an implant has poor mechanical resistance, which can render separation of tissue from the implant interface and induce epithelial downgrowth. Modification of the transmucosal surface of implants, which can help form a good seal of connective tissue, is therefore desired. We hypothesized that anodic oxidation (AO) and polydopamine (PD) deposition could be used to enhance the attachment between an implant and peri-implant connective tissue. We tested this hypothesis in the mandibles of Beagle dogs.

MATERIAL AND METHODS

AO and PD were used to modify the transmucosal region of transmucosal implants (implant neck). The surface microstructure, surface roughness and elemental composition were investigated in vitro. L929 mouse fibroblasts were cultured to test the effect of PD on cell adhesion. Six Beagle dogs were used for the in vivo experiment (n = 6 dogs per group). Three months after building the edentulous animal model, four groups of implants (control, AO, PD and AO + PD) were inserted. After 4 months of healing, samples were harvested for histometric analyses.

RESULTS

The surfaces of anodized implant necks were overlaid with densely distributed pores, 2-7 μm in size. On the PD-modified surfaces, N1s, the chemical bond of nitrogen in PD, was detected using X-ray photoelectron spectroscopy. L929 developed pseudopods more quickly on the PD-modified surfaces than on the surfaces of the control group. The in vivo experiment showed a longer connective tissue seal and a more coronally located peri-implant soft-tissue attachment in the AO + PD group than in the control group (P < .05).

CONCLUSION

The modification of AO + PD on the implant neck yielded better attachment between the implant and peri-implant connective tissue.