Mitochondria-Targeting Bimetallic Cluster Nanozymes Alleviate Neuropathic Pain through Scavenging ROS and Reducing Inflammation

Chemistry Medicinal Chemistry Nanoscience Neurology Life Sciences Cell Biology Immunology Medicine
mitochondria anti-inflammation neuropathic pain reactive oxygen species bimetallic nanozymes oxidative stress signaling pathways

Mitochondria-Targeting Bimetallic Cluster Nanozymes Alleviate Neuropathic Pain by Scavenging ROS and Reducing Inflammation

Background Introduction

Neuropathic pain is a complex and multifaceted public health issue, with its high incidence and significant negative impact on patients’ quality of life making it a critical area of medical research. Current treatment options for neuropathic pain are limited, with suboptimal efficacy and notable side effects of medications posing significant challenges. This situation drives researchers to continuously explore new therapeutic targets and methods to improve the management of chronic pain.

The formation mechanisms of neuropathic pain are highly complex. Activation of spinal cord glial cells, along with the accumulation of inflammatory mediators and reactive oxygen species (ROS) in the microenvironment, are among the primary pathogenic factors. Studies have shown that ROS generated in the central nervous system (CNS) can activate transcription factors such as nuclear factor-κB (NF-κB), leading to the expression of pro-inflammatory cytokines and chemokines that sustain and amplify pain perception in neurons. Furthermore, mitochondrial dysfunction is a critical factor, leading to abnormal oxidative stress and inflammatory responses that exacerbate neuropathic pain.

In recent years, nanozymes have garnered widespread attention. Nanozymes are nanoscale materials that mimic the catalytic function of natural enzymes and are widely used for disease treatment due to their high stability and biocompatibility. Among them, bimetallic nanozymes exhibit enhanced catalytic performance due to the synergistic effects of the metals. However, delivering these highly efficient nanozymes to disease-relevant subcellular structures, such as mitochondria, for precise treatment remains a challenge.

Against this background, this study introduces a mitochondria-targeted bimetallic cluster nanozyme (TPP-Au-Ru nanozyme) specifically designed for addressing neuropathic pain. The study focuses on reducing ROS levels and mitigating inflammation to improve pain perception, providing a novel direction for managing chronic pain.

Paper Information

This research was conducted by collaborative teams from the Affiliated Drum Tower Hospital of Nanjing University Medical School, the First Affiliated Hospital of Shandong First Medical University, and Zhengzhou University. The key researchers include Xiaolei Cheng and Xiaoping Gu, among others. The paper was published in the journal Advanced Healthcare Materials in 2025, with DOI: 10.1002/adhm.202401607.

Research Process

1. Nanozyme Synthesis and Characterization

In order to enable ROS scavenging and mitochondrial targeting, the research team synthesized a bimetallic Au-Ru nanozyme using ligand-interaction methods and further modified it for mitochondrial targeting by coupling with triphenylphosphonium (TPP). Through transmission electron microscopy (TEM), atomic force microscopy (AFM), dynamic light scattering (DLS), and Fourier-transform infrared (FT-IR) spectroscopy, the morphology, particle size, and surface chemistry of the nanozyme were analyzed. Results showed that the TPP-Au-Ru nanozyme exhibited good uniformity, with an average particle size of 3–5 nm. The addition of TPP successfully adjusted the surface zeta potential of the nanozyme from −35.46 mV to −13.086 mV, enhancing its dispersion.

In addition, enzymatic activity tests demonstrated that TPP-Au-Ru nanozyme exhibited superoxide dismutase (SOD)-like and catalase (CAT)-like catalytic capabilities, enabling it to scavenge superoxide radicals (•O2−), degrade hydrogen peroxide (H2O2), and promote oxygen production.

2. Evaluation of ROS Scavenging and Anti-inflammatory Performance

To verify the function of the nanozyme at the cellular level, the research team used BV2 microglial cells as a model, inducing ROS production and inflammation with lipopolysaccharides (LPS), then testing the effects of nanozyme intervention. Using flow cytometry and fluorescence microscopy, they observed that TPP-Au-Ru nanozyme significantly reduced intracellular ROS levels. Additionally, the nanozyme decreased the production of the lipid peroxidation biomarker 4-HNE and the concentration of malondialdehyde (MDA). Reverse transcription quantitative PCR (RT-qPCR) further revealed that LPS-induced increases in inflammatory mediators IL-1β, IL-6, and IL-8 were significantly downregulated following nanozyme treatment.

3. Improved Mitochondrial Function

Mitochondrial dysfunction is a key cause of ROS production and inflammatory responses. The research team further evaluated the impact of TPP-Au-Ru nanozyme on mitochondrial function. Using the JC-1 probe to measure mitochondrial membrane potential (ΔΨm), they found that the LPS-induced reduction in ΔΨm was reversed after nanozyme treatment. Additionally, TPP-Au-Ru nanozyme significantly restored mitochondrial ATP production.

In terms of regulating inflammatory signaling pathways, the nanozyme also suppressed the activation of MAPK and NF-κB signaling pathways, as evidenced by reduced phosphorylation levels of p65 and MAPK.

4. Pain Alleviation in Animal Models

Using a chronic constriction injury (CCI) mouse model, the TPP-Au-Ru nanozyme was successfully delivered to spinal cord and brain regions via tail vein injection. Behavioral tests showed that the nanozyme significantly alleviated pain perception in the CCI model mice, with analgesic effects lasting up to 36 hours. Histological analyses further confirmed that the nanozyme reduced ROS levels in the dorsal root ganglia (DRG), downregulated the expression of inflammatory factors, and inhibited the activation of p65 and MAPK.

Research Conclusions and Implications

Conclusions

The TPP-Au-Ru nanozyme developed in this study effectively scavenges ROS, mitigates inflammatory responses, and restores mitochondrial function. Its unique mitochondrial targeting delivery capability makes it a promising candidate for treating neuropathic pain. Additionally, the nanozyme’s high efficacy and safety profile suggest it could reduce reliance on current pharmacological and surgical interventions.

Scientific Significance

This study elucidates the pivotal role of ROS and inflammation in chronic pain and proposes a novel strategy that targets mitochondria for antioxidative and anti-inflammatory therapy. It provides an improved research direction for treating neuropathic pain.

Application Prospects

Beyond pain management, the antioxidative and anti-inflammatory properties of this nanozyme illuminate its potential application in areas like wound healing, cardiovascular diseases, and cancer therapy.

Highlights and Future Directions

  1. Innovation: This is the first instance of combining bimetallic nanozymes with mitochondrial targeting technology for neuropathic pain treatment.
  2. Sustained Efficacy: A single dose injection provides significant pain relief lasting up to 36 hours, outperforming traditional medications.
  3. Safety: The nanozyme demonstrates minimal biotoxicity and the ability to cross the blood-brain barrier, showcasing excellent application potential.

Future research could further investigate the metabolism, long-term safety, and repeated administration of TPP-Au-Ru nanozyme, as well as explore its therapeutic potential for other diseases.