Chinese researchers develop ultrasound nanoparticle platform against bacteria

Researchers in China have developed a bacteria-targeting nanoparticle platform that uses ultrasound to generate antibacterial molecules and carbon monoxide, effectively killing drug-resistant pathogens while promoting tissue repair. Multidrug-resistant bacterial infections represent a growing global health threat as conventional antibiotics lose their efficacy. Liang He of South China Agricultural University and Zhengyin Pan of Shenzhen Technology University led a team to create the bioorthogonal reaction-mediated, ultrasound-responsive nanoplatform, known as MnCyNPs-Tz, for synergistic antibacterial therapy and wound healing.

How the Nanoparticle Platform Targets Bacteria

The therapeutic platform encapsulates a multifunctional tricarbonyl Mn(I)-cyanine complex, designated Mn-Cy7, inside tetrazine-functionalized DSPE-PEG2000 micelles. Bacteria in the targeted area are first pre-labeled with trans-cyclooctene-polyethylene glycol4-phenylboronic acid, which selectively binds to cis-diol-rich glycans located on bacterial cell walls. The tetrazine groups on the surface of the nanoparticle then react rapidly and covalently with the trans-cyclooctene via an inverse electron-demand Diels-Alder bioorthogonal reaction. This chemical process enables precise bacterial anchoring and local enrichment of the treatment directly at the infection site.

Ultrasound Triggers Radicals and Gas to Disrupt Bacteria

Upon exposure to ultrasound irradiation, the Mn-Cy7 component generates hydroxyl radicals and releases carbon monoxide gas. Density functional theory calculations indicate that the IR-780 ligand narrows the highest occupied molecular orbital to lowest unoccupied molecular orbital gap to 2.32 eV, which facilitates ultrasound-triggered hydroxyl radical production and carbon monoxide release. This combined approach of Type-I sonodynamic therapy and gas therapy disrupts bacterial cell membranes, respiratory chains, energy metabolism, and biofilms.

Laboratory Results Against Drug-Resistant Strains

In in vitro testing, the targeted platform demonstrated potent activity against both Gram-positive and Gram-negative bacteria, including methicillin-resistant Staphylococcus aureus. Survival rates for tested pathogens dropped significantly, with Staphylococcus aureus reduced to 0.76 percent, Escherichia coli to 38.54 percent, and methicillin-resistant Staphylococcus aureus to 1.54 percent. Transcriptomic analysis revealed that the treatment interferes with oxidative stress responses, the respiratory chain, energy metabolism, and membrane integrity while showing a low propensity to induce bacterial resistance.

Animal Model Wound Healing Performance

In a murine methicillin-resistant Staphylococcus aureus-infected wound model, the targeted platform reduced bacterial survival to approximately 1 percent. The treatment achieved 99.1 percent wound closure within 10 days of application. The therapy promoted angiogenesis and stimulated M2 macrophage polarization, offering a precise non-antibiotic strategy to combat multidrug-resistant infections and accelerate tissue repair.