A Smart Bacteria-Capture-Killing Vector for Effectively Treating Osteomyelitis Through Synergy Under Microwave Therapy.

Osteomyelitis caused by deep tissue infections is difficult to cure through phototherapy due to the poor penetration depth of the light. Herein, Cu/C/Fe3O4-COOH nanorod composites (Cu/C/Fe3O4-COOH) with nanoscale tip convex structures are successfully fabricated as a microwave-responsive smart bacteria-capture-killing vector. Cu/C/Fe3O4-COOH exhibited excellent magnetic targeting and bacteria-capturing ability due to its magnetism and high selectivity affinity to the amino groups on the surface of Staphylococcus aureus (S. aureus). Under microwave irradiation, Cu/C/Fe3O4-COOH efficiently treated S. aureus-infected osteomyelitis through the synergistic effects of microwave thermal therapy, microwave dynamic therapy, and copper ion therapy. It is calculated the electric field intensity in various regions of Cu/C/Fe3O4-COOH under microwave irradiation, demonstrating that it obtained the highest electric field intensity on the surface of copper nanoparticles of Cu/C/Fe3O4-COOH due to its high-curvature tips and metallic properties. This led to copper nanoparticles attracted more charged particles compared with other areas in Cu/C/Fe3O4-COOH. These charges are easier to escape from the high curvature surface of Cu/C/Fe3O4-COOH, and captured by adsorbed oxygen, resulting in the generation of reactive oxygen species. The Cu/C/Fe3O4-COOH designed in this study is expected to provide insight into the treatment of deep tissue infections under the irradiation of microwave.

Sea urchin-like Bi2S3/curcumin heterojunction rapidly kills bacteria and promotes wound healing under near-infrared light.

Bacterial infection is an urgent public health problem. We design a novel photo-responsive hybrid material by growing small molecules of curcumin (Cur) in situ on a sea urchin-like Bi2S3 surface by a one-step hydrothermal reaction method, thus forming an organic-inorganic hybrid material with interfacial contact. The Bi2S3/Cur hybrid material has good antibacterial effect under 808 nm near-infrared (NIR) light irradiation. The antibacterial mechanism is that the electron redistribution at the interface of Bi2S3/Cur excited by 808 nm NIR light will cause a large number of electrons to gather on the side of Bi2S3, forming an internal electric field to drive the excited electrons from Bi2S3 to Cur, which accelerates the separation of photoexcited electron-hole pairs and enhances the production of reactive oxygen species (ROS). In conclusion, due to these synergistic effects of the photothermal properties of Bi2S3, the production of more ROS and the release of small molecules of Cur from traditional Chinese medicine in Bi2S3/Cur, the antibacterial efficacy against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) is 99.96% and 99.03%, respectively. In vivo experiments in animals show that Bi2S3/Cur can reduce the inflammatory response and promote wound healing. This paper presents a simple, rapid and safe strategy for the treatment of wound infections with near-infrared light.

Microwave assisted antibacterial action of Garcinia nanoparticles on Gram-negative bacteria.

Owing to the existence of the outer membrane barrier, most antibacterial agents cannot penetrate Gram-negative bacteria and are ineffective. Here, we report a general method for narrow-spectrum antibacterial Garcinia nanoparticles that can only be effective to kill Gram-positive bacteria, to effectively eliminate Gram-negative bacteria by creating transient nanopores in bacterial outer membrane to induce drug entry under microwaves assistance. In vitro, under 15 min of microwaves irradiation, the antibacterial efficiency of Garcinia nanoparticles against Escherichia coli can be enhanced from 6.73% to 99.48%. In vivo, MV-assisted GNs can effectively cure mice with bacterial pneumonia. The combination of molecular dynamics simulation and experimental results reveal that the robust anti-E. coli effectiveness of Garcinia nanoparticles is attributed to the synergy of Garcinia nanoparticles and microwaves. This work presents a strategy for effectively treating both Gram-negative and Gram-positive bacteria co-infected pneumonia using herbal medicine nanoparticles with MV assistance as an exogenous antibacterial auxiliary.

Treatment of MRSA-infected osteomyelitis using bacterial capturing, magnetically targeted composites with microwave-assisted bacterial killing.

Owing to the poor penetration depth of light, phototherapy, including photothermal and photodynamic therapies, remains severely ineffective in treating deep tissue infections such as methicillin-resistant Staphylococcus aureus (MRSA)-infected osteomyelitis. Here, we report a microwave-excited antibacterial nanocapturer system for treating deep tissue infections that consists of microwave-responsive Fe3O4/CNT and the chemotherapy agent gentamicin (Gent). This system, Fe3O4/CNT/Gent, is proven to efficiently target and eradicate MRSA-infected rabbit tibia osteomyelitis. Its robust antibacterial effectiveness is attributed to the precise bacteria-capturing ability and magnetic targeting of the nanocapturer, as well as the subsequent synergistic effects of precise microwaveocaloric therapy from Fe3O4/CNT and chemotherapy from the effective release of antibiotics in infection sites. The advanced target-nanocapturer of microwave-excited microwaveocaloric-chemotherapy with effective targeting developed in this study makes a major step forward in microwave therapy for deep tissue infections.