pH-Triggered nanoreactors as oxidative stress amplifiers for combating multidrug-resistant biofilms

Adoptive cell transfer of piezo-activated macrophage rescues immunosuppressed rodents from life-threating bacterial infections

Bacterial infections pose a significant threat to human health. Catalytic antibacterial nanoparticles that generate reactive oxygen species (ROS) are emerging, as a promising therapeutic approach in treating bacterial infection by boosting the innate immune defenses. However, the interaction between innate immune cells and these catalytic nanoparticles remains poorly understood. Here, by using rodent models of bacterial infection, we test the antimicrobial properties of ultrasound-responsive piezo-catalytic nanoparticles (piezoNP). We show that piezoNPs strongly interact with macrophages within subcutaneous abscesses caused by Staphylococcus aureus (S. aureus) infections, and demonstrate that this interaction enhances the macrophage-mediated antibacterial phagocytosis and killing activity through intracellular piezocatalysis. Moreover, we test the use of these piezo-activated macrophages (piezoMϕ) as adoptive cell therapy (ACT) for treating various immunosuppressive bacterial infections, including sepsis, pneumonia and peritonitis. Our study thus highlights the potential application of catalytic nanoparticles as a promising alternative to conventional infection treatment to effectively modulate the innate immune responses and to engineer macrophages for immunotherapy purposes.

Bio-Responsive Sliver Peroxide-Nanocarrier Serves as Broad-Spectrum Metallo-β-lactamase Inhibitor for Combating Severe Pneumonia

Metallo-β-lactamases (MBLs) represent a prevalent resistance mechanism in Gram-negative bacteria, rendering last-line carbapenem-related antibiotics ineffective. Here, a bioresponsive sliver peroxide (Ag2 O2 )-based nanovesicle, named Ag2 O2 @BP-MT@MM, is developed as a broad-spectrum MBL inhibitor for combating MBL-producing bacterial pneumonia. Ag2 O2 nanoparticle is first orderly modified with bovine serum albumin and polydopamine to co-load meropenem (MER) and [5-(p-fluorophenyl)-2-ureido]-thiophene-3-carboxamide (TPCA-1) and then encapsulated with macrophage membrane (MM) aimed to target inflammatory lung tissue specifically. The resultant Ag2 O2 @BP-MT@MM effectively abrogates MBL activity by displacing the Zn2+ cofactor in MBLs with Ag+ and displays potent bactericidal and anti-inflammatory properties, specific targeting abilities, and great bioresponsive characteristics. After intravenous injection, the nanoparticles accumulate prominently at infection sites through MM-mediated targeting . Ag+ released from Ag2 O2 decomposition at the infection sites effectively inhibits MBL activity and overcomes the resistance of MBL-producing bacteria to MER, resulting in synergistic elimination of bacteria in conjunction with MER. In two murine infection models of NDM-1+ Klebsiella pneumoniae-induced severe pneumonia and NDM-1+ Escherichia coli-induced sepsis-related bacterial pneumonia, the nanoparticles significantly reduce bacterial loading, pro-inflammatory cytokine levels locally and systemically, and the recruitment and activation of neutrophils and macrophages. This innovative approach presents a promising new strategy for combating infections caused by MBL-producing carbapenem-resistant bacteria.

pH Switchable Nanozyme Platform for Healing Skin Tumor Wound Infected with Drug-Resistant Bacteria

Nanozymes capable of generating reactive oxygen species have recently emerged as promising treatments for wounds infected with drug-resistant bacteria, possessing a reduced possibility of inducing resistance. However, the therapeutic effect is limited by a shortage of endogenous oxy-substrates and undesirable off-target biotoxicity. Herein, a ferrocenyl coordination polymer (FeCP) nanozyme, featuring pH switchable peroxidase (POD)- and catalase (CAT)-like activity is incorporated with indocyanine green (ICG) and calcium peroxide (CaO2 ) to fabricate an H2 O2 /O2 self-supplying system (FeCP/ICG@CaO2 ) for precise treatment of bacterial infections. At the wound site, CaO2 reacts with water to generate H2 O2 and O2 . Acting as a POD mimic under an acidic bacterial microenvironment, FeCP catalyzes H2 O2 into hydroxyl radicals to prevent infection. However, FeCP switches to CAT-like activity in neutral tissue, decomposing H2 O2 into H2 O and O2 to prevent oxidative damage and facilitate wound healing. Additionally, FeCP/ICG@CaO2 shows photothermal therapy capability, as ICG can emit heat under near-infrared laser irradiation. This heat assists FeCP in fully exerting its enzyme-like activity. Thus, this system achieves an antibacterial efficiency of 99.8% in vitro for drug-resistant bacteria, and effectively overcomes the main limitations of nanozyme-based treatment assays, resulting in satisfactory therapeutic effects in repairing normal and special skin tumor wounds infected with drug-resistant bacteria.

Metal-organic framework-encapsulated nanoparticles for synergetic chemo/chemodynamic therapy with targeted H2O2 self-supply

Nanocatalytic cancer therapy based on chemodynamic therapy, which converts hydrogen peroxide (H2O2) into toxic reactive oxygen species via the Fenton-like reaction, is regarded as a promising therapeutic strategy due to its specific response toward the tumor microenvironment (TME). However, the H2O2 concentration in TME (100 μM to 1 mM) is insufficient and introducing enough H2O2 or H2O2-generating agents is challenging. In view of this, we report a drug delivery system, CaO2/DOX@Cu/ZIF-8@HA (CDZH), which is capable of targeted H2O2 self-supply and exhibits outstanding chemo/chemodynamic synergetic therapy capability. CaO2/DOX@Cu/ZIF-8@HA is synthesized by fabricating biodegradable Cu/ZIF-8 shell-encapsulated CaO2 nanoparticles, loading chemotherapy drug doxorubicin, and coating a hyaluronic acid shell. In an acidic tumor microenvironment, the CDZH nanostructures targeted the release of doxorubicin, Cu2+, and CaO2. Doxorubicin affects chemotherapy and bioimaging, and CaO2 supplies H2O2 through a Cu-Fenton-like reaction to generate hydroxyl radicals with high oxidation activity for chemodynamic therapy. In brief, the drug delivery system combined targeted H2O2 self-supply and targeted bioimaging possess the potential of an efficient synergistic strategy for chemodynamic therapy and chemotherapy.