Enhanced cellular osteogenic differentiation on Zn-containing bioglass incorporated TiO2 nanorod films

Surface nanotopography and bioactive ions have been considered to play critical roles on the interactions of biomaterials with cells. In this study, a TiO₂ nanorod film incorporated with Zn-containing bioactive glass (TiO₂/Zn-BG) was prepared on tantalum substrate, trying to evaluate the synergistic effects of nanotopograpgy and bioactive ions to promote cellular osteogenic differentiation activity. The expression of osteogenic-related genes, ALP as well as the ECM mineralization on TiO₂/Zn-BG film were significantly upregulated compared to that of the film without TiO₂ nanorod nanostructure (Zn-BG) or without Zn (TiO₂/BG). Moreover, a much low Zn²⁺ release level on TiO₂/Zn-BG film was beneficial to promote the osteogenesis, which could be ascribed to that a semi-closed space established by TiO₂ nanorods with adhered cells provided an appropriate micro-environment that facilitated Zn²⁺ adsorption.

Cathodic Polarization Coats Titanium Based Implant Materials with Enamel Matrix Derivate (EMD)

The idea of a bioactive surface coating that enhances bone healing and bone growth is a strong focus of on-going research for bone implant materials. Enamel matrix derivate (EMD) is well documented to support bone regeneration and activates growth of mesenchymal tissues. Thus, it is a prime candidate for coating of existing implant surfaces. The aim of this study was to show that cathodic polarization can be used for coating commercially available implant surfaces with an immobilized but functional and bio-available surface layer of EMD. After coating, XPS revealed EMD-related bindings on the surface while SIMS showed incorporation of EMD into the surface. The hydride layer of the original surface could be activated for coating in an integrated one-step process that did not require any pre-treatment of the surface. SEM images showed nano-spheres and nano-rods on coated surfaces that were EMD-related. Moreover, the surface roughness remained unchanged after coating, as it was shown by optical profilometry. The mass peaks observed in the matrix-assisted laser desorption/ionization time-of-flight mass spectroscopy (MALDI-TOF MS) analysis confirmed the integrity of EMD after coating. Assessment of the bioavailability suggested that the modified surfaces were active for osteoblast like MC3M3-E1 cells in showing enhanced Coll-1 gene expression and ALP activity.

Biomechanical and antibacterial properties of Tobramycin loaded hydroxyapatite coated fixation pins

The present study investigates the use of nanoporous, biomimetic hydroxyapatite (HA) coatings deposited on TiO₂ coated fixation pins as functional implant surfaces for the local release of Tobramycin in order to prevent bacterial colonization. The impact of HA-coating thickness, coating morphology and biomechanical forces during insertion into synthetic bone on the drug loading and release properties are analyzed. The coatings are shown to exhibit bactericidal effects against Staphylococcus aureus in agar medium for a duration of 6 days after loading by adsorption with Tobramycin for only 5 min at elevated temperature and pressure. Furthermore, high performance liquid chromatography analysis shows a drug release in phosphate buffered saline for 8 days with antibiotic concentration remaining above the minimal inhibitory concentration for S. aureus during the entire release period. Biomechanical insertion tests into synthetic bone and conventional scratch testing demonstrate adhesive strength at the HA/TiO₂ interface. Biocompatibility is verified by cell viability tests. Outgrowth endothelial cells, as well as primary osteoblasts, are viable and firmly attached to both HA and TiO₂ surfaces. The results presented are encouraging and support the concept of functional HA coatings as local drug delivery vehicles for biomedical applications to treat as well as to prevent post-surgical infections.

Significance of calcium phosphate coatings for the enhancement of new bone osteogenesis--a review

A systematic analysis of results available from in vitro, in vivo and clinical trials on the effects of biocompatible calcium phosphate (CaP) coatings is presented. An overview of the most frequently used methods to prepare CaP-based coatings was conducted. Dense, homogeneous, highly adherent and biocompatible CaP or hybrid organic/inorganic CaP coatings with tailored properties can be deposited. It has been demonstrated that CaP coatings have a significant effect on the bone regeneration process. In vitro experiments using different cells (e.g. SaOS-2, human mesenchymal stem cells and osteoblast-like cells) have revealed that CaP coatings enhance cellular adhesion, proliferation and differentiation to promote bone regeneration. However, in vivo, the exact mechanism of osteogenesis in response to CaP coatings is unclear; indeed, there are conflicting reports of the effectiveness of CaP coatings, with results ranging from highly effective to no significant or even negative effects. This review therefore highlights progress in CaP coatings for orthopaedic implants and discusses the future research and use of these devices. Currently, an exciting area of research is in bioactive hybrid composite CaP-based coatings containing both inorganic (CaP coating) and organic (collagen, bone morphogenetic proteins, arginylglycylaspartic acid etc.) components with the aim of promoting tissue ingrowth and vascularization. Further investigations are necessary to reveal the relative influences of implant design, surgical procedure, and coating characteristics (thickness, structure, topography, porosity, wettability etc.) on the long-term clinical effects of hybrid CaP coatings. In addition to commercially available plasma spraying, other effective routes for the fabrication of hybrid CaP coatings for clinical use still need to be determined and current progress is discussed.

Photocatalysis induces bioactivity of an organic polymer based material

Bioactivity of resin–TiO₂ nanocomposite induced by TiO₂ photocatalysis under UV irradiation.

Advanced Nanomeasuring Techniques for Surface Characterization

Advanced precise and accurate nanomeasurement techniques play an important role to improve the function and quality of surface characterization. There are two basic approaches, the hard measuring techniques and the soft computing measuring techniques. The advanced soft measuring techniques include coordinate measuring machines, roundness testing facilities, surface roughness, interferometric methods, confocal optical microscopy, scanning probe microscopy, and computed tomography at the level of nanometer scale. On the other hand, a new technical committee in ISO is established to address characterization issues posed by the areal surface texture and measurement methods. This paper reviews the major advanced soft metrology techniques obtained by optical, tactile, and other means using instruments, classification schemes of them, and their applications in the engineering surfaces. Furthermore, future trends under development in this area are presented and discussed to display proposed solutions for the important issues that need to be addressed scientifically.

Photocatalytic and antimicrobial properties of surgical implant coatings of titanium dioxide deposited though cathodic arc evaporation

Nanostructured crystalline titanium dioxide coatings deposited by cathodic arc evaporated on titanium grade five medical implant substrates were demonstrated to exhibit UV-induced photocatalytic activity that can be utilized to provide bactericidal effects against Staphylococcus epidermidis. The photocatalytic activity of the coatings was confirmed via degradation of Rhodamine B under UV illumination. A 90 % reduction of viable bacteria was achieved in a clinically suitable time of only 2 min with a UV dose of 2.4 J delivered at 365 nm. These results are encouraging for the development of antimicrobial surfaces in orthopedics and dentistry in order to prevent or treat post-surgical infections.

PURPOSE OF WORK

To assess the possibility of employing photocatalysis for elimination of S. epidermidis, known to cause medical device related infections, under short enough times to be clinically useful on an implant surface produced with a technique that is suitable for mass production.