Preparation of Vanillic Acid-Loaded Core-Shell Gold Nanospheres/Mesoporous Silica Nanoparticles for the Treatment of Orthopedic Infection

Orthopedic infection is a serious complication in surgeries and remains a great challenge in clinics. Here, the natural antimicrobial compound vanillic acid-loaded gold nanospheres/mesoporous silica nanoparticles (VA@Au-MSNs) were fabricated for chemo-photothermal synergistic therapy to orthopedic infections. The shape and morphology of Au-MSN and VA@Au-MSN were observed by scanning electron microscopy and transmission electron microscopy. The properties of VA@Au-MSN or related components were characterized by dynamic light scattering, thermogravimetric analysis, Brunauer-Emmett-Teller (BET) analysis, and photothermal analysis. Vanillic acid released from VA@Au-MSN was detected in phosphate-buffered saline. A cytotoxicity test and an antibacterial assessment were performed to explore the biosafety and antibacterial activity of VA@Au-MSN, respectively. The results showed that Au-MSN possessed a high BET surface area (458 m(2)/g). After loading vanillic acid, the BET surface area reduced to 72 m(2)/g. The loading efficiency of Au-MSN was 18.56%. Under 808 nm laser irradiation, the temperature at the wound site injected with the Au-MSN solution in the mouse increased from 24 to 60 degrees C within about 12 s. Also, the high temperature could promote the release of vanillic acid from VA@Au-MSN. Additionally, VA@Au-MSN has no obvious cytotoxicity to MC3T3-E1 cells, but the generated local hyperthermia and the VA released from VA@Au-MSN had excellent antibacterial activity against Staphylococcus aureus in a synergistic way. In conclusion, the VA@Au-MSN with biosafety and excellent antibacterial performance might be applied for the treatment of orthopedic infection.

Automated summary

VA@Au-MSN nanoparticles were designed for chemo-photothermal synergistic therapy of orthopedic infections, demonstrating excellent antibacterial activity against Staphylococcus aureus without cytotoxicity to bone cells. The unique properties of the nanoparticles allowed for controlled release of vanillic acid at the site of infection, providing a promising approach for the treatment of orthopedic infections.