Self-Fueling Hydrogel Heals MRSA-Infected Diabetic Wounds in Mice

Diabetic wounds are among the most stubborn problems in modern medicine, and a new study from Materials Today Bio offers a creative attack on them. Researchers have built an injectable hydrogel that scavenges the very molecules produced by infected wounds and converts them into bacteria-killing weapons. In experiments on mice with methicillin-resistant Staphylococcus aureus (MRSA) infected wounds, the material closed nearly 98 percent of the wound area by day 18, while untreated wounds remained open and inflamed. The work combines materials chemistry, nanotechnology, and immunology into a single dressing-like system, and although it remains far from the clinic, it illustrates how the hostile chemistry of a chronic wound can be turned against the bacteria that thrive there.

The clinical backdrop is sobering. According to the researchers, roughly a quarter of people with diabetes develop slow-healing wounds during their lifetime, and in 60 to 80 percent of cases those wounds become infected by bacteria. MRSA is particularly dangerous in this setting, since it resists conventional antibiotics and can form protective biofilms on the wound surface. Existing hydrogel dressings, often based on polyvinyl alcohol or polyethylene glycol, have static structures that cannot respond to the shifting acidity and reactive oxygen chemistry of an infected wound, and enzyme-loaded materials so far have mostly relied on single-step catalytic reactions or externally supplied drugs.

The team’s answer is a material they call CPONM, built from two natural polymers and a synthetic nanoparticle. The first polymer is chitosan, a sugar-derived substance from crustacean shells that is naturally antibacterial and biocompatible, modified with phenylboronic acid groups. The second is oxidized dextran, a sugar polymer whose oxidation creates aldehyde groups. When mixed, these two polymers form two kinds of reversible chemical links at once: boronate ester bonds and Schiff base bonds. This dual dynamic network gives the gel its remarkable properties, including the ability to flow through a syringe needle, to heal itself after being cut, and to stick firmly to wet tissue with a measured adhesive strength of 13.43 kilopascals.

Embedded within this network are nanoparticles made from naringenin, a flavonoid from citrus fruits, coordinated with manganese ions. Naringenin has long attracted interest for its anti-inflammatory effects, but its extreme insolubility and instability have limited its use. By binding it to manganese, the researchers created stable nanoparticles roughly 15 nanometers in diameter that carry two enzyme-like activities. They mimic superoxide dismutase, converting superoxide anions into hydrogen peroxide, and they mimic peroxidase, converting hydrogen peroxide into hydroxyl radicals, which are among the most destructive oxidants known to biology. Because infected diabetic wounds accumulate excess superoxide and hydrogen peroxide naturally, the nanoparticles can use these endogenous molecules as fuel, which the authors describe as a self-fueling cascade catalytic reaction requiring no external input.

Laboratory characterization confirmed the design. Electron microscopy showed a porous sponge-like structure with an average pore size of 111.46 micrometers, and porosity measurements using ethanol displacement found pore volumes of 85 to 87 percent, features that support gas exchange and cell migration. Spectroscopic analysis confirmed the formation of both boronate ester and Schiff base bonds, and showed that the nanoparticles were evenly dispersed in the polymer matrix. The gel swelled to over twelve times its original weight in water, remained mechanically stable over time, and degraded faster in acidic conditions, which is precisely the environment of an infected wound. In self-healing tests, cut halves of the gel fused back together within five minutes of contact.

Release experiments demonstrated that the material responds intelligently to wound chemistry. At a pH of 5.5, simulating an infected acidic wound, nearly 79 percent of the naringenin was released over 48 hours, compared with about 52 percent at an alkaline pH of 8.0. Adding hydrogen peroxide at 100 micromolar accelerated release further, reaching 85.22 percent, because the oxidant cleaves the boronate bonds. Manganese ions were released more slowly and less completely, reflecting their tighter coordination within the nanoparticles. The researchers interpret this as a targeted delivery system that dumps its cargo precisely where inflammation and bacterial activity have made the tissue acidic and oxidizing, and holds it back elsewhere.

Antimicrobial testing showed the payoff. Against E. coli, the complete hydrogel inhibited 93.15 percent of bacterial growth, and against MRSA it inhibited 94.74 percent, roughly 35 to 45 percentage points better than a hydrogel containing only the polymer network. Crystal violet staining confirmed that the material also disrupted bacterial biofilms, with inhibition rates above 90 percent for both species. In live mice with streptozotocin-induced type 2 diabetes and MRSA-infected full-thickness skin wounds, the bacterial counts in wound tissue dropped dramatically by day 9, with a measured bacteriostatic rate of 93.85 percent for the complete hydrogel. By day 18, the wound area in the treated group had shrunk by 97.47 percent, compared with only 70.69 percent in untreated controls, and histological staining showed mature epidermis, organized collagen, and active new blood vessel formation rather than necrotic tissue and inflammatory infiltrate.

The immunological results may be equally important. Macrophages, the immune cells that dominate chronic wounds, often get stuck in a pro-inflammatory state in diabetes, preventing healing. In laboratory tests with inflammatory macrophage models, the hydrogel significantly reduced production of iNOS and IL-6, markers of the destructive M1 state, and pushed the cells toward the reparative M2 phenotype. Western blot analysis of wound tissue revealed that the treatment suppressed the NF-κB inflammatory signaling pathway, blocking the phosphorylation of IκB-α, while simultaneously activating the Nrf2 antioxidant pathway and its target genes NQO1 and HO-1. Immunohistochemistry confirmed increased CD206, a marker of reparative macrophages, along with elevated VEGF and α-SMA, both associated with blood vessel maturation. The authors attribute this dual effect to the naringenin component, which is known to influence these pathways, working alongside the nanoparticle’s catalytic activity.

Biocompatibility data are encouraging but preliminary. Hemolysis rates stayed below 3 percent, under the 5 percent international safety threshold for biomedical materials, and fibroblast cells exposed to the gel extracts remained fully viable. Cell migration assays showed that the complete hydrogel increased scratch closure rates in fibroblast cultures to nearly 59 percent, far above the untreated control’s 25 percent. The material also showed strong antioxidant activity in standard chemical assays, scavenging both ABTS and DPPH radicals in a dose-dependent manner.

The authors are candid about the road ahead. Long-term biocompatibility and the fate of manganese ions in the body remain untested, including whether the metal accumulates in organs or disrupts metal homeostasis. The material was only evaluated against MRSA and E. coli, leaving other clinically important pathogens unexamined. The mouse model involved small-area skin defects, and larger wounds or deep tissue injuries may behave differently. Scaling up synthesis of the modified polymers while maintaining reproducibility is another hurdle. Still, the study demonstrates a compelling principle: that the very chemistry which makes diabetic wounds hostile, an excess of reactive oxygen molecules and acidic pH, can be exploited as fuel for a self-sustaining catalytic cycle that kills bacteria, calms inflammation, and promotes tissue repair, all from a single injectable material.

Subject of Research: A self-fueling naringenin-manganese hydrogel for treating MRSA-infected diabetic wounds

Article Title: Naringenin-Mn self-fueling dual-dynamic hydrogel with cascade catalysis and immunomodulation properties for repairing MRSA -infected diabetic wounds

Article References: Qi, M., Li, T., Chen, G., Wang, G., Dai, G., Xue, J., & Zhang, C. (2026). Naringenin-Mn self-fueling dual-dynamic hydrogel with cascade catalysis and immunomodulation properties for repairing MRSA-infected diabetic wounds. Materials Today Bio, 41, Article 103787. https://doi.org/10.1016/j.mtbio.2026.103787

Image Credits: AI Generated

DOI: 10.1016/j.mtbio.2026.103787

Keywords: diabetic wounds, MRSA, hydrogel, nanozyme, naringenin, manganese, cascade catalysis, reactive oxygen species, macrophage polarization, wound healing, biofilm, NF-kB signaling