Silk fibroin-based coating with pH-dependent controlled release of Cu2+ for removal of implant bacterial infections.

The implantation of medical devices is frequently accompanied by the invasion of bacteria, which may lead to implant failure. Therefore, an intelligent and responsive coating seems particularly essential in hindering implant-associated infections. Herein, a self-defensive antimicrobial coating, accompanied by silk fibroin as a valve, was successfully prepared on the titanium (Ti-Cu@SF) for pH-controlled release of Cu2+. The results showed that the layer could set free massive Cu2+ to strive against E. coli and S. aureus for self-defense when exposed to a slightly acidic condition. By contrary, a little Cu2+ was released in the physiological situation, which could avoid damage to the normal cells and showed excellent in vitro pH-dependent antibiosis. Besides, in vivo experiment confirmed that Ti-Cu@SF could work as an antibacterial material to kill S. aureus keenly and display negligible toxicity in vivo. Consequently, the design provided support for endowing the layer with outstanding biocompatibility and addressing the issue of bacterial infection during the implantation of Ti substrates.

Fabrication of graphene oxide/copper synergistic antibacterial coating for medical titanium substrate.

Titanium (Ti) was an excellent medical metal material, but the lack of good antibacterial activity confined its further practical application. To solve this dilemma, a coating containing graphene oxide (GO) and copper (Cu) was prepared on the surface of Ti sheet (Ti/APS/GO/Cu). First, physical sterilization could be carried out through the sharp-edged sheet structure of GO. Second, the oxygen-containing functional group on the surface of GO and the released Cu2+ would generate reactive oxygen species for chemical sterilization. The synergistic effect of GO and Cu substantially enhanced the in vitro and in vivo antibacterial property of Ti sheet, thereby reducing bacterial-related inflammation. Quantitatively, the antibacterial rate of Ti/APS/GO/Cu against E. coli or S. aureus reached over 99%. Besides, Ti/APS/GO/Cu showed excellent biocompatibility and no toxicity to cell. Such work developed multiple sterilization avenues to design non-antibiotic, safe and efficient antibacterial implant material for the biomedical domain.

Fabrication of a TiO2@Cu Core-Shell Nanorod Array as Coating for Titanium Substrate with Mechanical and Chemical Dual Antibacterial Property.

Titanium (Ti) is an excellent medical metal material, but the absence of good antibacterial property restricts its widespread application. To overcome this, we thus conducted a series of modifications for Ti. First, a titanium dioxide (TiO2) nanorod array was generated on the Ti surface by hydrothermal treatment (TiO2/Ti). With the polymer-mediated self-assembly method, a continuous copper (Cu) shell structure on the surface of the nanorod was then generated to form a TiO2@Cu core-shell nanorod array as coating for Ti (TiO2@Cu/Ti). Using pure Ti as the control group, the antibacterial properties of TiO2/Ti and TiO2@Cu/Ti were appraised. The results manifested that the mechanical and chemical dual function of the released Cu2+ and TiO2 nanorod array could effectively kill bacteria on the surface of Ti. Besides, the obtained coating exhibited no cytotoxicity and favorable biocompatibility. In this work, we found an antibacterial strategy based on multiple sterilization pathways, which made Ti have good antibacterial property and further improved its biocompatibility.

Implanting a Copper Ion into a TiO2 Nanorod Array for the Investigation on the Synergistic Antibacterial Mechanism between Mechanical Cracking and Chemical Damage.

Titanium (Ti) and its alloys are extensively applied in dental and orthopedic implants due to their characteristics of good mechanical property and corrosion resistance. However, Ti and its alloys suffer from the absence of certain biological activity and antibacterial ability. Herein, we synthesized a titanium dioxide (TiO2) nanorod array on the surface of a Ti plate, and the obtained TiO2 nanorod array was further modified by Cu ions through ion implantation technology in an attempt to endow medical Ti with an antibacterial ability and maintain a normal biological function synchronously. The antibacterial ability of the TiO2 nanorod array with the incorporation of Cu ions was vastly improved compared with those of the unmodified TiO2 nanorod array and pure Ti. In particular, owing to the synergy between the chemical damage of the released Cu2+ to the cell and the mechanical cracking of the TiO2 nanorod array, the antibacterial rate of the TiO2 nanorod array modified by Cu ions against Escherichia coli or Staphylococcus aureus could reach 99%. In addition, no cytotoxicity was detected in such prepared coating during the CCK-8 assay. Moreover, the corrosion resistance of the sample was significantly better than that of pure Ti. Overall, we demonstrated that the application of ion implantation technology could open up a promising pathway to design and develop further antibacterial material for the biomedical domain.