An In Vitro Evaluation of the Hierarchical Micro/Nanoporous Structure of a Ti3Zr2Sn3Mo25Nb Alloy after Surface Dealloying

Flexible free-standing antibacterial nanoporous Ag ribbon

The biomedical field has the potential to significantly benefit from the use of flexible free-standing Ag nanostructures due to their outstanding mechanical and antibacterial properties. However, the intricate process of synthesizing these nanostructures, as well as the potential toxicity of nanostructured Ag, pose significant challenges. This study used a facile etching method to synthesize the free-standing nanoporous Ag (NP-Ag) ribbons with a homogeneous and bicontinuous three-dimensional ligament structure. The free-standing NP-Ag ribbons demonstrated stable mechanical performance and excellent flexibility when subjected to various deformation states on artificial fingers. Additionally, the NP-Ag ribbons exhibited remarkable antibacterial capacity with rates of 99.81 ± 0.14% against Escherichia coli, 96.11 ± 1.49% against Staphylococcus aureus, and 95.37 ± 1.24% against methicillin-resistant Staphylococcus aureus. The antibacterial mechanism of NP-Ag is attributed to the rapid release of Ag ions (Ag⁺) in 24 h, causing damage to the bacterial membrane. Moreover, the in vivo results demonstrate that the NP-Ag ribbons provide rapid antibacterial efficacy and are biosafe due to the long-term stable Ag⁺ release of NP-Ag. The development of these free-standing flexible NP-Ag ribbons offers a new avenue for wearable antibacterial applications.

Early osseointegration of micro-arc oxidation coated titanium alloy implants containing Ag: a histomorphometric study

BACKGROUND

This study aimed to evaluate bone response to micro-arc oxidation coated titanium alloy implants containing Ag.

METHODS

144 titanium alloy implants were prepared by machine grinding and divided into three treatment groups as following, SLA group: sand-blasting and acid-etched coating; MAO group: micro-arc oxidation without Ag coating; MAO + Ag group: micro-arc oxidation containing Ag coating. Surface characterization of three kind of implants were observed by X-ray diffraction, energy dispersive X-ray spectrometer, scanning electron microscopy, High Resolution Transmission Electron Microscope and roughness analysis. The implants were inserted into dog femurs. 4, 8 and 12 weeks after operation, the bone response to the implant to the bone was evaluated by push-out experiment, histological and fluorescent labeling analysis.

RESULTS

MAO + Ag group consisted of a mixture of anatase and rutile. Ag was found in the form of Ag₂O on the surface. The surface morphology of MAO + Ag group seemed more like a circular crater with upheaved edges and holes than the other two groups. The surface roughness of MAO and MAO + Ag groups were higher than SLA group, but no statistical difference between MAO and MAO + Ag groups. The contact angles in MAO + Ag group was smallest and the surface free energy was the highest among three groups. The maximum push-out strength of MAO and MAO + Ag groups were higher than SLA group at all time point, the value of MAO + Ag group was higher than MAO group at 4 and 8 weeks. Scanning electron microscopy examination for the surface and cross-section of the bone segments and fluorescent labeling analysis showed that the ability of bone formation and osseointegration in MAO + Ag group was higher than that of the other two groups.

CONCLUSION

The micro-arc oxidation combination with Ag coating is an excellent surface modification technique to posse porous surface structure and hydrophilicity on the titanium alloy implants surface and exhibits desirable ability of osseointegration.

Construction of a Hierarchical Micro-/Submicro-/Nanostructured 3D-Printed Ti6Al4V Surface Feature to Promote Osteogenesis: Involvement of Sema7A through the ITGB1/FAK/ERK Signaling Pathway

Constructing hierarchical hybrid structures is considered a facile method to improve the osseointegration of implants. Herein, a hierarchical micro-/submicro-/nanostructured surface feature of Ti6Al4V implants (3DAT group) was successfully constructed by combining the inherently formed three-dimensional (3D)-printed microscale topography, acid-etched sub-micropits, and anodized nanotubes. Compared with the classical SLA surface, the microscale topography and sub-micropits increased the three-dimensional space for the cell growth and mechanical stability of implants, while the modification of nanotubes dramatically improved the surface hydrophilicity, protein adsorption, and biomineralization. Most importantly, the 3DAT surface feature possessed excellent osteogenic performance in vitro and in vivo, with the involvement of semaphorin 7A (Sema7A) as revealed by RNA-seq through the ITGB1/FAK/ERK signaling pathway. The present study suggested that the hierarchically structured surface design strategy could accelerate the osseointegration rate of 3D-printed Ti6Al4V implants, promising personalized reconstruction of bone defects.

Biocompatibility of NbTaTiVZr with Surface Modifications for Osteoblasts

We report a potential biomedical material, NbTaTiVZr, and the impact of surface roughness on the osteoblast culture and later behavior based on in vitro tests of preosteoblasts. Cell activities such as adhesion, viability, and typical protein activity on NbTaTiVZr showed comparable results with that of commercially pure Ti (CP-Ti). In addition, NbTaTiVZr with a smooth surface exhibits better cell adhesion, viability, and typical protein activity which shows that surface modification can improve the biocompatibility of NbTaTiVZr. This supports the biological evidence and shows that NbTaTiVZr can potentially be evaluated as a biomedical material for clinical use.

Multifunctional Coatings of Titanium Implants Toward Promoting Osseointegration and Preventing Infection: Recent Developments

Titanium and its alloys are dominant material for orthopedic/dental implants due to their stable chemical properties and good biocompatibility. However, aseptic loosening and peri-implant infection remain problems that may lead to implant removal eventually. The ideal orthopedic implant should possess both osteogenic and antibacterial properties and do proper assistance to in situ inflammatory cells for anti-microbe and tissue repair. Recent advances in surface modification have provided various strategies to procure the harmonious relationship between implant and its microenvironment. In this review, we provide an overview of the latest strategies to endow titanium implants with bio-function and anti-infection properties. We state the methods they use to preparing these efficient surfaces and offer further insight into the interaction between these devices and the local biological environment. Finally, we discuss the unmet needs and current challenges in the development of ideal materials for bone implantation.