Metal–carbon
hybrid materials have shown promise as potential
enzyme mimetics for antibacterial therapy; however, the effects of
metal states and corresponding antibacterial mechanisms are largely
unknown. Here, two kinds of copper/carbon nanozymes were designed,
with tuned copper states from Cu0 to Cu2+. Results
revealed that the copper/carbon nanozymes exhibited copper state-dependent
peroxidase-, catalase-, and superoxide dismutase-like activities.
Furthermore, the antibacterial activities were also primarily determined
by the copper state. The different antibacterial mechanisms of these
two copper/carbon nanozymes were also proposed. For the CuO-modified
copper/carbon nanozymes, the released Cu2+ caused membrane
damage, lipid peroxidation, and DNA degradation of Gram-negative bacteria,
whereas, for Cu-modified copper/carbon nanozymes, the generation of
reactive oxygen species (ROS) via peroxidase-like catalytic reactions
was the determining factor against both Gram-positive and Gram-negative
bacteria. Lastly, we established two bacterially infected animal models,
i.e., bacteria-infected enteritis and wound healing, to confirm the
antibacterial ability of the copper/carbon nanozymes. Our findings
provide a deeper understanding of metal state-dependent enzyme-like
and antibacterial activities and highlight a new approach for designing
novel and selective antibacterial therapies based on metal–carbon
nanozymes.
The use of natural substance to ward off microbial infections has a long history. However, the large-scale production of natural extracts often reduces antibacterial potency, thus limiting practical applications. Here we present a strategy for converting natural organosulfur compounds into nano-iron sulfides that exhibit enhanced antibacterial activity. We show that compared to garlic-derived organosulfur compounds nano-iron sulfides exhibit an over 500-fold increase in antibacterial efficacy to kill several pathogenic and drug-resistant bacteria. Furthermore, our analysis reveals that hydrogen polysulfanes released from nano-iron sulfides possess potent bactericidal activity and the release of polysulfanes can be accelerated by the enzyme-like activity of nano-iron sulfides. Finally, we demonstrate that topical applications of nano-iron sulfides can effectively disrupt pathogenic biofilms on human teeth and accelerate infected-wound healing. Together, our approach to convert organosulfur compounds into inorganic polysulfides potentially provides an antibacterial alternative to combat bacterial infections.
Infections caused by bacteria are a growing global challenge for public health as bacteria develop resistance, which will cause the failure of anti-infective treatment eventually. An effective alternative strategy to traditional antibacterial therapy is utilizing reactive oxygen species (ROS) to kill bacteria. Here, we report a simple route to prepare PEGylated nitrogen-doped carbon capsules (PEG-N-CCs) as an antibacterial agent. The PEG-N-CCs can translate near-infrared light (NIR) into heat and produce a high concentration of ROS triggered by NIR irradiation. Both heating and ROS are critical to destroy the outer membranes and rupture cell bodies, causing DNA fragmentation and glutathione oxidation both in Gram-negative Escherichia coli, Gram-positive Staphylococcus aureus, and their multidrug-resistant strains. Moreover, PEG-N-CCs plus NIR irradiation can efficiently scavenge the existing biofilms and prevent the formation of new biofilms, killing planktonic bacteria as well as those within the biofilm. Our studies prove that the PEG-N-CCs plus NIR irradiation can provide a simple and effective platform for combating bacteria, employing carbon nanomaterials as an antibacterial alternative for treatment of infectious diseases.
Cerebral
ischemic stroke stimulates excessive reactive oxygen species,
which lead to blood–brain-barrier disruption, neuron death,
and aggravated cerebral infarction. Thus, it is critical to develop
an antioxidant strategy for stroke treatment. Herein, we report a
dietary strategy to promote stroke healing using iron oxide (Fe3O4) nanoparticles with intrinsic enzyme-like activities.
We find that Fe3O4 nanozymes exhibit triple
enzyme-like activities, peroxidase, catalase, and superoxide dismutase,
thus potentially possessing the ability to regulate the ROS level.
Importantly, intragastric administration of PEG-modified Fe3O4 nanozymes significantly reduces cerebral infarction
and neuronal death in a rodent model following cerebral ischemic stroke. Ex vivo analysis shows that PEG-modified Fe3O4 nanozymes localize in the cerebral vasculature, ameliorate
local redox state with decreased malondialdehyde and increased Cu/Zn
SOD, and facilitate blood–brain-barrier recovery by elevating
ZO-1 and Claudin-5 in the hippocampus. Altogether, our results suggest
that dietary PEG-modified Fe3O4 nanozymes can
facilitate blood–brain-barrier reconstruction and protect neurons
following ischemic stroke.
Inspired
by the particularity of tumor microenvironments, including
acidity and sensibility to reactive oxygen species (ROS), advanced
and smart responsive nanomaterials have recently been developed. The
present study synthesized tumor-targeted and pH-sensitive supramolecular
micelles that self-assembled via host–guest
recognition. The micelles consumed intratumoral glucose and lactate via loading with glucose oxidase (GOD) and lactate oxidase
(LOD). Intratumoral glucose and lactate were converted into hydrogen
peroxide (H2O2) and were sequentially reduced
to highly toxic hydroxyl radicals (•OH) via the peroxidase (POD)-like activity of the loaded C-dot
nanozymes. Tumor-killing effects were observed via cascade catalytic reactions. After an intravenous injection, the
nanocomposite exhibited an excellent tumor-targeted ability with good
biocompatibility, which demonstrated its effective antitumor effect.
The nanocomposite effectively combined starvation and catalytic therapies
and exerted a synergistic anticancer effect with minimal side effects
and without external addition.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.