A Dual Role of Copper on the Surface of Bone Implants

Feasibility study on Ti-15Mo-7Cu with low elastic modulus and high antibacterial property

Titanium and titanium alloy with low density, high specific strength, good biological, excellent mechanical compatibility and easy to process have been widely used in the medical materials, but their application in orthopedics and dentistry often face bacterial infection, corrosion failure and stress shielding. In this paper, Ti-15Mo-7Cu (TM-7Cu) alloy was prepared by high vacuum non-consumable electric arc melting furnace and then treated by solution and aging treatment. The microstructure, mechanical properties, antibacterial properties and cytocompatibility were studied by X-ray diffraction, microhardness tester, electrochemical working station, antibacterial test and Live/Dead staining technology. The results have shown that the heat treatment significantly influenced the phase transformation, the precipitation of Ti₂Cu phase, the elastic modulus and the antibacterial ability. With the extension of the aging time, the elastic modulus slightly increased and the antibacterial rate obviously increased. TM-7Cu alloy with a low elastic modulus of 83GPa and a high antibacterial rate of > 93% was obtained. TM-7Cu alloy showed no cytotoxicity to MC3T3. It was suggested that TM-7Cu might be a highly competitive medical material.

Development of a low elastic modulus and antibacterial Ti-13Nb-13Zr-5Cu titanium alloy by microstructure controlling

In order to prepare a titanium with a low elastic modulus and good antibacterial property to meet the requirements as a biomedical material, Ti-13Nb-13Zr-5Cu (TNZ-5Cu) alloy was prepared by high vacuum consume electric arc melting furnace and then subjected to a solution treatment at 950 °C followed by a short-term aging treatment at 600 °C, for 15 min, 30 min, 1 h and 2 h, respectively. The microstructure, mechanical property, antibacterial property and biocompatibility of TNZ-5Cu were investigated in detail. The research results have shown that the solid solution treated alloy was mainly composed of β-phase and α″-phase, while the aged alloys of β-phase, α″-phase, α-phase and Ti₂Cu. Compared with Ti-13Nb-13Zr alloy (65 GPa) and Ti-6Al-4 V alloy (111 GPa), the elastic modulus of TNZ-5Cu alloy after solution treatment was about 72 GPa and increased with the aging treatment up to 85 GPa, and the hardness was maintained at a higher level than that of Ti-13Nb-13Zr alloys (288 HV). The bacteria plate count results showed that the antibacterial ability of TNZ-5Cu alloy increased with the extension of the aging duration from <60% at 15-30 min to >90% at 1-2 h. Cell experiments showed that all TNZ-5Cu alloy had good cell compatibility. The low modulus and the antibacterial property could provide potential to avoid stress shield and device-related inflection in the clinical application.

Effect of ultrasonic micro-arc oxidation on the antibacterial properties and cell biocompatibility of Ti-Cu alloy for biomedical application

In order to improve antibacterial properties and cell biocompatibility of Ti-Cu alloy, an ultrasonic micro-arc oxidation (UMAO) has been applied to Ti-Cu alloy. The corrosion resistance, antibacterial activity and cell compatibility of Ti-Cu alloy before and after UMAO were studied in detail by means of electrochemical test, plate count method and CCK-8 test scanning electron microscopy (SEM) technology to evaluate the application possibilities of UMAO as a surface bio-modification method for Ti-Cu alloy. The surface microstructure characterisation showed that a typical porous coating with a pore diameter of 3-8 μm and a thickness of 5-15 μm was formed on the surface of the Ti-Cu alloy, which significantly improved the surface roughness and hydrophilicity. The plate count method demonstrated that UMAO coatings on Ti-Cu alloy showed strong antibacterial activity (≥99%) against Staphylococcus aureus (S. aureus) even after being immersed in a physiological saline for up to 20 days, indicating that UMAO-treated Ti-Cu alloy had very strong long-term antibacterial properties. It is believed that the strong long-term antimicrobial properties of Ti-Cu-UMAO samples were mainly due to the formation of Cu₂O and CuO in UMAO coatings. The results of cell compatibility evaluation showed that UMAO treatment did not bring about cytotoxicity but improved the early adhesion of MC3T3 cell.

Bone grafts and biomaterials substitutes for bone defect repair: A review

Bone grafts have been predominated used to treat bone defects, delayed union or non-union, and spinal fusion in orthopaedic clinically for a period of time, despite the emergency of synthetic bone graft substitutes. Nevertheless, the integration of allogeneic grafts and synthetic substitutes with host bone was found jeopardized in long-term follow-up studies. Hence, the enhancement of osteointegration of these grafts and substitutes with host bone is considerably important. To address this problem, addition of various growth factors, such as bone morphogenetic proteins (BMPs), parathyroid hormone (PTH) and platelet rich plasma (PRP), into structural allografts and synthetic substitutes have been considered. Although clinical applications of these factors have exhibited good bone formation, their further application was limited due to high cost and potential adverse side effects. Alternatively, bioinorganic ions such as magnesium, strontium and zinc are considered as alternative of osteogenic biological factors. Hence, this paper aims to review the currently available bone grafts and bone substitutes as well as the biological and bio-inorganic factors for the treatments of bone defect.

Copper as an alternative antimicrobial coating for implants - An in vitro study

AIM

To investigate osteoconductive and antimicrobial properties of a titanium-copper-nitride (TiCuN) film and an additional BONIT^® coating on titanium substrates.

METHODS

For micro-structuring, the surface of titanium test samples was modified by titanium plasma spray (TPS). On the TPS-coated samples, the TiCuN layer was deposited by physical vapor deposition. The BONIT^® layer was coated electrochemically. The concentration of copper ions released from TiCuN films was measured by atomic absorption spectrometry. MG-63 osteoblasts on TiCuN and BONIT^® were analyzed for cell adhesion, viability and spreading. In parallel, Staphylococcus epidermidis (S. epidermidis) were cultivated on the samples and planktonic and biofilm-bound bacteria were quantified by counting of the colony-forming units.

RESULTS

Field emission scanning electron microscopy (FESEM) revealed rough surfaces for TPS and TiCuN and a special crystalline surface structure on TiCuN + BONIT^®. TiCuN released high amounts of copper quickly within 24 h. These release dynamics were accompanied by complete growth inhibition of bacteria and after 2 d, no planktonic or adherent S. epidermidis were found on these samples. On the other hand viability of MG-63 cells was impaired during direct cultivation on the samples within 24 h. However, high cell colonization could be found after a 24 h pre-incubation step in cell culture medium simulating the in vivo dynamics closer. On pre-incubated TiCuN, the osteoblasts span the ridges and demonstrate a flattened, well-spread phenotype. The additional BONIT^®coating reduced the copper release of the TiCuN layer significantly and showed a positive effect on the initial cell adhesion.

CONCLUSION

The TiCuNcoating inhibits the formation of bacterial biofilms on orthopedic implants by influencing the “race for the surface” to the advantage of osteoblasts.

Preparation and in vitro osteogenic, angiogenic and antibacterial properties of cuprorivaite (CaCuSi4O10, Cup) bioceramics

Cuprorivaite firstly synthesized by sol–gel method with angiogenic and antibacterial activities for wound healing application.

Bioinorganics and biomaterials: bone repair

The field of bioinorganics is well established in the development of a variety of therapies. However, their application to bone regeneration, specifically by way of localized delivery from functional implants, is in its infancy and is the topic of this review. The toxicity of inorganics is species, dose and duration specific. Little is known about how inorganic ions are effective therapeutically since their use is often the result of serendipity, observations from nutritional deficiency or excess and genetic disorders. Many researchers point to early work demonstrating a role for their element of interest as a micronutrient critical to or able to alter bone growth, often during skeletal development, as a basis for localized delivery. While one can appreciate how a deficiency can cause disruption of healing, it is difficult to explain how a locally delivered excess in a preclinical model or patient, which is presumably of normal nutritional status, can evoke more bone or faster healing. The review illustrates that inorganics can positively affect bone healing but various factors make literature comparisons difficult. Bioinorganics have the potential to have just as big an impact on bone regeneration as recombinant proteins without some of the safety concerns and high costs.