This elegant nanoflower adds antioxidant, antibacterial and antibiofilm properties when applied to electrospun nanofiber bandages. (Credit: Adapted from ACS Applied Bio Materials 2025, DOI: 10.1021/acsabm.4c00788)
In a nutshell
- Scientists created flower-shaped nanomaterials from copper and tannic acid that can kill bacteria, reduce biofilm formation, and neutralize harmful free radicals—key challenges in wound healing. These “nanoflowers” combine three essential healing functions in a single material, potentially offering a powerful alternative to antibiotics.
- The nanoflowers were embedded into a fiber-based wound dressing that’s safe for human cells, blood-compatible, and effective against common wound-infecting bacteria like Staphylococcus aureus, E. coli, and Pseudomonas aeruginosa.*
- This green, low-energy synthesis method uses natural plant compounds and may offer a sustainable, customizable solution for treating chronic or antibiotic-resistant wounds in the future.
GENOA, Italy — The next generation of wound dressings might bloom like a flower. Scientists have developed microscopic “nanoflowers” that combine copper and tannic acid into structures resembling tiny carnations with remarkable healing properties. These flower-shaped particles can kill bacteria, break down protective biofilms, and soak up harmful free radicals, offering a triple-threat approach to wound healing when antibiotic resistance is on the rise.
Whether from burns, surgeries, or accidents, damaged skin needs proper care to heal correctly. Bacteria like Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa often infect these wounds, making them harder to treat. Doctors typically prescribe antibiotics, but overuse has led to resistant bacteria that no longer respond to these medications.
From Plant Compounds to Powerful Medicine
The study, published in ACS Applied Bio Materials, took an eco-friendly approach by using natural ingredients to create wound-healing technology. Rather than harsh chemicals, they used tannic acid, a compound found in tree bark, tea, and wine. This substance organized copper ions into flower-shaped structures measuring about 15 micrometers across.
Tannic acid works well for this purpose because of its molecular structure. Thanks to its natural composition, it can bind to metal ions like copper. In plants, tannic acid serves various functions including defense against predators and pathogens. When mixed with copper in a phosphate solution, these molecules organize themselves into intricate, flower-shaped structures.
These copper-tannic acid nanoflowers (Cu-TA NFs) effectively neutralize harmful reactive oxygen molecules that form during inflammation. These unstable molecules, called reactive oxygen species (ROS), can damage cells if they accumulate in excess. By scavenging these molecules, the nanoflowers help create better conditions for healing.
Fighting Bacteria Where They Hide
To make a practical wound dressing, the team incorporated their nanoflowers into a specially designed material. They created fibers from natural and synthetic materials (a plant-derived gum and a water-soluble polymer), coated them with a biodegradable plastic layer, and then added the nanoflowers. This composite material combines the best properties of each component.
In lab tests, the nanoflower-enhanced dressings fought off both major types of bacteria: the thick-walled kind (like staph infections) and the thin-walled kind (like E. coli) that cause most wound infections. They also disrupted biofilms, which are communities of bacteria that form a protective shield making them extremely hard to kill with conventional antibiotics.
The researchers also tested whether their material would harm human cells. They found it didn’t damage red blood cells, showing good blood compatibility. The material also supported the growth of fibroblasts, cells that help repair damaged tissue, and worked well with human skin cells called keratinocytes.
A Multi-Functional Approach to Wound Healing
This approach tackles multiple wound-healing challenges at once. The dressings protect against external contamination, kill existing bacteria, prevent treatment-resistant biofilm formation, neutralize harmful oxygen molecules, and create conditions that promote healing.
The team found they could increase the effectiveness of their dressings by adding more nanoflowers. When they raised the concentration from 10% to 20%, both the antibacterial activity and antioxidant properties improved, suggesting doctors could potentially adjust the formulation to suit different types of wounds.
The production method itself is remarkably simple and environmentally friendly. The nanoflowers form spontaneously in a room-temperature solution without energy-intensive processes or harmful chemicals. This green chemistry approach makes the technology more sustainable and potentially easier to scale up for commercial production.
Future Potential for Difficult-to-Treat Wounds
Patients with diabetes, vascular diseases, or weakened immune systems often develop wounds that won’t heal with standard treatments. The combination of antimicrobial, anti-biofilm, and antioxidant properties in these new dressings could offer a better solution for cases like these.
This research fits into a growing trend of using natural compounds in advanced medical materials. Plants have developed sophisticated chemical defenses over millions of years of evolution. As more bacteria outsmart our antibiotics, these tiny copper-tannic acid flowers represent a powerful alternative drawn from nature’s own defenses.
Paper Summary
Methodology
The nanoflowers were created by mixing copper sulfate with tannic acid in a phosphate buffer solution and allowing it to incubate at room temperature for 72 hours. During this period, copper ions interacted with phosphate to form crystals, while tannic acid bound to these crystals through hydroxyl groups, creating the flower-like structure. For the wound dressing, the team electrospun nanofibers from gum arabic and poly(vinyl alcohol), coated them with poly(caprolactone), and then incorporated the nanoflowers through an adsorption process in isopropanol.
Results
The copper-tannic acid nanoflowers demonstrated strong antioxidant properties, effectively scavenging harmful free radicals. When incorporated into nanofiber wound dressings at concentrations of 10% and 20%, they showed significant antibacterial activity against both Gram-positive (S. aureus) and Gram-negative bacteria (E. coli and P. aeruginosa). They inhibited biofilm formation by up to 47%, displayed excellent blood compatibility, and promoted the growth of fibroblasts and keratinocytes, which are essential for wound healing.
Limitations
This study was limited to laboratory testing rather than clinical trials on actual wounds. The long-term stability of the nanoflowers in the dressings wasn’t investigated, which would affect shelf life and sustained effectiveness. No comparisons were made with existing commercial wound care products, making relative advantages difficult to assess. The potential release of copper ions over time and its implications for safety and efficacy weren’t examined.
Discussion and Takeaways
These nanoflower dressings address multiple aspects of wound healing simultaneously: infection control, antioxidant protection, and creation of favorable conditions for tissue regeneration. Their effectiveness against biofilms is particularly valuable since biofilm-related infections represent about 65% of bacterial infections and typically resist conventional treatments. The use of natural compounds aligns with increasing interest in eco-friendly medical materials, while the ability to adjust nanoflower concentration offers potential for customized wound treatments.
Funding and Disclosures
This research was supported by the Ministry of University and Research in Italy as part of the FSE REACT-EU-PON 2014-2020 program, with additional support from Italy’s National Institute of Nuclear Physics (Genoa Unit) for specialized equipment access. The researchers declared no competing financial interests.
Publication Information
The study “Self-Assembled Nanoflowers from Natural Building Blocks with Antioxidant, Antibacterial, and Antibiofilm Properties” was published in ACS Applied Bio Materials (Volume 8, pages 152-165) on January 6, 2025. The research team included scientists from the University of Genoa, Italy, and Tarbiat Modares University in Iran.
