Biofunctional Elements Incorporated Nano/Microstructured Coatings on Titanium Implants with Enhanced Osteogenic and Antibacterial Performance

Abstract

Bone fracture is prevalent among athletes and senior citizens and may require surgical insertion of bone implants. Titanium (Ti) and its alloys are widely used in orthopedics due to its high corrosion resistance, good biocompatibility, and modulus compatible with natural bone tissues. However, bone repair and regrowth are impeded by the insufficient intrinsic osteogenetic capability of Ti and Ti alloys and potential bacterial infection. The physicochemical properties of the materials and nano/microstructures on the implant surface are crucial for clinical success and loading with biofunctional elements such as Sr, Zn, Cu, Si, and Ag into nano/microstructured TiO 2 coating has been demonstrated to enhance bone repair/regeneration and bacterial resistance of Ti implants. In this review, recent advances in biofunctional element-incorporated nano/microstructured coatings on Ti and Ti alloy implants are described and the prospects and limitations are discussed.

Advanced Surface Modification for 3D-Printed Titanium Alloy Implant Interface Functionalization

“…Strontium (Sr) is an important osteogenic trace element which is widely used as an oral drug for the treatment of osteoporosis ( Wang et al, 2020 ). The comparison of Sr 2+ and other divalent ions (Mg 2+ , Ca 2+ , Ba 2+ ) shows that Sr 2+ has a more significant effect on promoting bone formation, inhibitory effect on osteoclastogenesis, immunogenicity, and fibrosis ( Xu et al, 2020 ). The exact mechanism of Sr 2+ in osseointegration remains unclear, but it has been proposed that Sr 2+ acts on similar cellular targets as Ca 2+ by activating the calcium-sensing receptor (CaSR), thus interacting with Ca-driven signaling pathways related to bone metabolism regulation ( Wan et al, 2020 ).…”

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

“…The gradient coating solved the problem of weak interfacial bond, prevented the diffusion of metal ions effectively, and improved the surface osteoconductivity. Besides HA, various metal ions (Ca 2+ , Sr 2+ , Mg 2+ ) have been demonstrated to possess the property to promote osseointegration ( Xu et al, 2020 ). One example of these coatings is a biomimetic mesoporous coating doped with strontium (MPs-Sr), proposed by Zhang et al (2018a) .…”

NanoZnO-modified titanium implants for enhanced anti-bacterial activity, osteogenesis and corrosion resistance

“…Abnormally high osteoclast activity could result in excessive bone resorption. Consequently, reducing excessive osteoclastic-induced bone resorption would facilitate implant-bone integration [ 16 ]. It was reported that the binding of RANKL to RANK activates nuclear factor κB (NF-κB), which then induces osteoclastic differentiation [ 137 ].…”

“…It is well-known that the formation of neovascularization is extremely valuable for bone regeneration, as it promotes nutrient delivery and bone repair [ 150 ]. Thus, clinical success depends not only on the osseointegration around the Ti implant, but also on the neovascularization [ 16 ]. Various growth factors secreted by osteoblasts, e.g.…”

“…Besides, bacteria bonded to the surface of the implant to form a biofilm that prevents cells from attaching to the implant surface, further aggravating the loosening of the implant in bone tissue [ 12 ]. In patients with poor bone quality, the repair of necrotic tissue is difficult to manage due to the poor vascularity of infected bone tissue, resulting in a particularly long treatment process with a poor prognosis [ 15 , 16 ].…”