reactive oxygen species

Overview

Reactive oxygen species (ROS) are chemically reactive, oxygen-derived molecules and radicals, including superoxide, hydrogen peroxide, hydroxyl radical, and singlet oxygen. They arise endogenously as byproducts of aerobic metabolism — principally from electron leak at complexes I and III of the mitochondrial respiratory chain — and are also generated deliberately by NADPH oxidases and by peroxisomal and cytochrome P450 reactions. The species interconvert along a defined path: superoxide dismutase converts superoxide to hydrogen peroxide, which is either reduced to water by catalase, glutathione and glutathione peroxidases including GPX4, and the thioredoxin system, or, in the presence of ferrous iron, converted by Fenton chemistry to the hydroxyl radical. Because they differ in reactivity and diffusion range, hydrogen peroxide acts as a comparatively stable second messenger while the hydroxyl radical reacts near-indiscriminately at its site of formation, and only the antioxidant network standing between them keeps the first from becoming the second.

At physiological levels ROS are signals: they reversibly oxidize cysteine residues on phosphatases, kinases, and transcriptional regulators, shaping proliferation, differentiation, hypoxic adaptation via HIF-1α, and antimicrobial killing by phagocytes. The Nrf2/HO-1 axis is the principal adaptive response, inducing heme oxygenase 1 and related cytoprotective enzymes. When production outstrips clearance, the resulting oxidative stress oxidizes lipids, proteins and nucleic acids, activates NF-κB and the NLRP3 inflammasome with downstream caspase-1 and proinflammatory cytokine release, impairs mitochondrial function, and triggers regulated cell death — notably ferroptosis, in which iron-dependent lipid peroxidation proceeds once GPX4 activity or glutathione supply is insufficient. These mechanisms underpin the involvement of ROS in diabetes and diabetic wound healing, sepsis and organ injury, drug-induced liver injury, ischemia-reperfusion injury, fibrosis, neurodegeneration including Alzheimer's and Parkinson's disease, and tumor progression within the tumor microenvironment.

The same chemistry is used therapeutically, in both directions. Generating ROS where they are wanted is the effector mechanism of three related modalities: photodynamic therapy excites a photosensitizer with light of a specific wavelength to transfer energy to molecular oxygen, yielding singlet oxygen; sonodynamic therapy excites a sonosensitizer with ultrasound in the same way; and chemodynamic therapy needs no external energy at all, delivering transition metals that convert the hydrogen peroxide already abundant in tumors into hydroxyl radicals through Fenton or Fenton-like reactions. All three are used against tumor cells and against bacterial biofilms formed by organisms such as Staphylococcus aureus and Escherichia coli, and all three are limited by the glutathione of the target tissue, which motivates paired GSH-depletion strategies. Ionizing radiation kills partly by the same route, through radiolysis of water. Conversely, antioxidant and ROS-scavenging agents, including polyphenols and flavonoids such as kaempferol, are investigated to limit oxidative injury — an approach whose record is mixed, since indiscriminate scavenging removes the signaling species along with the damaging ones. ROS-responsive chemistry — thioketal linkers that cleave in oxidative environments, for example — is meanwhile used to build prodrugs, nanocarriers, hydrogels, and microneedle systems that release drugs such as paclitaxel or doxorubicin selectively where oxidative stress is high.

Recent Publications Summary (latest 30 papers)

Recent publications have extensively investigated reactive oxygen species (ROS) as both a therapeutic mechanism and a target for disease intervention, revealing dual therapeutic strategies across diverse pathologies. In cancer therapy, multiple studies exploited ROS-generating modalities including photodynamic therapy, sonodynamic therapy, and chemodynamic approaches. These investigations demonstrated that organelle-targeted photosensitizers could concentrate ROS at critical subcellular sites to enhance therapeutic efficacy; for example, lysosome-targeted photosensitizers showed superior photocytotoxicity against pancreatic cancer cells 42186767May. ROS-generating nanoparticles based on coassembled small molecules integrated light-controlled nitric oxide release to synergistically inhibit tumor growth and suppress epithelial-mesenchymal transition 42579410Aug. In glioma models, self-assembling peptide fibers that generate ROS in mitochondria were delivered via exosomes to preferentially disrupt cancer cell energy metabolism, achieving 3.7-fold higher ROS production in the assembled state compared to monomers 42455661Jul. Long-acting X-ray-induced dynamic therapy using organic nanoparticles achieved persistent ROS generation and luminescence for deep-tissue tumor treatment beyond conventional light penetration limits 42175828May.

Recognizing that elevated ROS is a hallmark of many disease microenvironments, researchers extensively developed ROS-responsive drug delivery platforms that leverage pathological oxidative stress to trigger therapeutic release. A ROS-triggered disassembly strategy using nanoparticle-networked hydrogels enabled dynamic modulation of corneal tight junctions for enhanced antifungal drug delivery in fungal keratitis, where the hydrogel consumed ROS while releasing loaded nanoparticles 42587441Aug. Similar ROS-responsive mechanisms were employed in thioketal-linked prodrugs for cancer chemotherapy; near-infrared imaging nanoparticles with ROS-triggered release of paclitaxel created a positive feedback loop in which treatment-generated ROS amplified drug release within the tumor microenvironment 42269794Jun42202709May. In diabetic wounds, nanoparticle-cross-linked hydrogels utilized dual-stage ROS responsiveness to sequentially disassemble and release epigallocatechin gallate for ROS scavenging and tobramycin for antibacterial action 42479468Jul. ROS-responsive liposomes were similarly engineered for acute kidney injury treatment, where elevated ROS from ischemia-reperfusion injury triggered release of farnesoid X receptor agonists to suppress ferroptosis 42018446Apr.

Emerging applications targeted ROS within specific disease-related signaling pathways and cellular mechanisms. High-frequency spinal cord stimulation downregulated the ROS/p38 MAPK/NF-κB signaling pathway to reduce microglial activation and proinflammatory cytokine release, thereby alleviating neuropathic pain and promoting spinal cord injury repair in rat models 42596832Aug. In glioma cells, the phytochemical cryptotanshinone targeted ferroptosis through the EGFR/ROS signaling pathway, promoting ROS accumulation, mitochondrial membrane potential loss, and ferroptosis-mediated cell death 42348047Jun. Structure-property relationship analysis revealed that α-keto ester prodrugs of monomethyl fumarate exploit elevated pathological ROS to trigger Baeyer-Villiger oxidation, enabling site-selective NRF2 activation for treating oxidative stress-driven peripheral neuropathy 42412905Jul. In viral infections, arbovirus-induced excessive ROS generation was identified as a mechanism that enhances viral replication and dysregulates immune responses, suggesting ROS control as a therapeutic intervention point 41986933Apr.

Complementary approaches leveraged engineered antioxidant nanomedicines and ROS-scavenging catalysts to protect tissues from oxidative damage in acute injury and chronic disease contexts. Metal-organic complex-engineered artificial metalloenzymes with Mn-Ru clusters demonstrated cascade ROS elimination for protecting against cerebral ischemic-reperfusion injury through synergistic SOD-like and catalase-like activities 42089182May. Cerium oxide nanoparticles exploiting Ce³⁺/Ce⁴⁺ redox cycling mimicked both SOD and catalase enzymatic functions; when co-loaded with antimicrobial peptides and bilirubin, these nanoparticles improved sepsis survival from 0% to 60% and ameliorated sepsis-related encephalopathy by maintaining blood-brain barrier integrity 42031058Apr. In diabetic wound therapy, MXene nanosheets integrated into self-healing hydrogels provided photothermal antibacterial activity while glutathione moieties scavenged ROS and promoted neovascularization, achieving 96% wound closure 42024460Apr. Injectable self-healing bioadhesive hydrogels incorporating kaempferol demonstrated ROS scavenging and antibacterial activities against Staphylococcus aureus and E. coli, accelerating oral ulcer healing through enhanced re-epithelialization 41995139Apr. Lipid-conjugated manganese Salen catalysts delivered via liposomes provided sustained Intracellular ROS reduction in acetaminophen-challenged hepatic cells 42275385Jun. Additionally, a biocompatible glycine-modified and amylase-responsive bilayer film with catechol-zinc nano-enzymes provided sustained SOD-mimicking ROS scavenging and macrophage polarization in oral ulcer models 41989817Apr.

Recent studies also explored ROS-generating mechanisms in specialized therapeutic applications. A GSH-scavenging microneedle patch incorporating copper tetrakis(carboxyphenyl)porphyrin combined ROS generation with glutathione synthesis inhibition to enhance photodynamic eradication of diabetic wound biofilms 42300219Jun. glutathione-triggered in situ formation of oxygen vacancies in iron oxyhydroxide nanospindles enhanced sonocatalytic therapy through improved charge separation, concurrent Fenton reaction-mediated ROS generation, and ferroptosis induction in tumors 42261917Jun. Mechanically enhanced nanoparticle-networked hydrogels responsive to the inflammatory microenvironment of diabetic wounds achieved antimicrobial, anti-inflammatory, and antioxidant effects through sequential ROS-responsive disassembly 42479468Jul. In retinoblastoma, a dimeric cabazitaxel prodrug linked via a thioketal bridge and co-assembled with photosensitizer chlorin e6 generated a burst of ROS upon near-infrared illumination that triggered prodrug release in a positive feedback loop 42269794Jun. Mitochondria-targeted zwitterionic nanogels induced photopyroptosis in cancer cells through ROS amplification and activation of the caspase-3/gasdermin E pathway, achieving 99.3% tumor inhibition 42143709May. In type 1 diabetes, biomimetic nanoparticles combining cerium oxide cores with NLRP3 inflammasome inhibitors effectively eliminated Intracellular ROS and reduced pancreatic β-cell apoptosis in streptozocin-induced diabetic mice 42144245May. Furthermore, multicolor mechanoluminescent nanoparticles generating tunable ROS-responsive chemiluminescence enabled ultrasound-triggered neuromodulation for deep-brain applications 41974592Apr.

What Changes, What Holds

1. Subcellular ROS localization enhances therapeutic efficacy in cancer models
REINFORCES Organelle-targeted photosensitizers and self-assembling peptide fibers concentrate ROS generation at mitochondrial or lysosomal sites to amplify photocytotoxicity and achieve higher efficacy than non-targeted approaches 42186767May42455661Jul. The Overview establishes photodynamic, sonodynamic, and chemodynamic therapy as established modalities; this work sharpens the principle through subcellular compartmentalization and integration with complementary mechanisms without displacing the core ROS-generating approach.

2. ROS-responsive delivery consumes pathological oxidative stress to trigger drug release across diverse diseases
REINFORCES Nanoparticles and hydrogels exploit elevated ROS at injury sites to sequentially release therapeutics including paclitaxel in tumors, farnesoid X receptor agonists in acute kidney injury, and antimicrobial agents in diabetic wounds 42269794Jun42018446Apr. The Overview already identifies thioketal linkers and ROS-responsive systems; this work validates and extends the principle across multiple pathologies without changing the underlying mechanism.

3. ROS regulation in specialized pathways offers therapeutic benefits through suppression rather than scavenging
NEW DIRECTION High-frequency spinal cord stimulation suppresses neuropathic pain by downregulating the ROS/p38 MAPK/NF-κB pathway 42596832Aug, and cryptotanshinone exploits EGFR/ROS signaling to promote ferroptosis in glioma 42348047Jun. The Overview establishes ROS as pathogenic at high levels; these studies identify therapeutic benefit from specific upstream pathway suppression and identify novel regulators (p38 MAPK, EGFR) that extend beyond the established Nrf2/HO-1 adaptive axis.

4. Engineered nanozymes achieve robust antioxidant catalysis that addresses the mixed efficacy of chemical scavengers
REINFORCES Artificial metalloenzymes and cerium oxide nanoparticles demonstrating SOD-like and catalase-like activities achieved 60% sepsis survival and ameliorated ischemic-reperfusion injury by synergistic cascade ROS elimination 42031058Apr. The Overview notes antioxidant agents have mixed clinical records; engineered biomimetics of natural antioxidant enzymes extend that established approach through synthetic catalysis rather than relying on chemical scavenging.

5. ROS modulation enters specialized neurological and autoimmune disease contexts
NEW DIRECTION Biomimetic nanoparticles reduce pancreatic β-cell apoptosis in type 1 diabetes-related pathology, and mechanoluminescent particles enable ultrasound-triggered neuromodulation for deep-brain applications 42144245May41974592Apr. The Overview addresses ROS roles in cancer, infection, and wound healing; these applications extend ROS control to neuroinflammatory and autoimmune-mediated diseases where underlying pathogenic mechanisms differ from established contexts.

Overview update candidates: Subcellular ROS targeting in photodynamic therapy; ROS suppression in neuropathic pain; engineered nanozymes with catalytic activity; acute kidney injury treatment via ROS-responsive delivery; type 1 diabetes β-cell protection.