Engineering healing with nanofiber antibiotic delivery

A new kind of bandage is taking shape in a Kraków laboratory, the perfect bandage. One that doesn’t just cover a wound, but actively delivers medicine right where it’s needed, slowly, steadily, and without the side effects of swallowing a pill. It looks like an ordinary piece of fabric, yet within its delicate fibers lies a system designed to fight infection with precision. This is the focus of a study published in [The Journal of Physical Chemistry B] by a team from the **Institute of Nuclear Physics of the Polish Academy of Sciences in Kraków**. Physicists Olga Adamczyk, Ewa Juszyńska-Gałązka, Aleksandra Deptuch, Tomasz Tarnawski, Piotr Zieliński, and Anna Drzewicz have engineered nanofiber mats that can deliver the antibiotic **metronidazole** directly to where it’s needed. Steadily, safely, and without the side effects of conventional treatments. Most of us take medicine in the form of pills, injections, or creams. But these “conventional” methods have a big drawback: they often flood the whole body with the drug, even when only a small area needs treatment. That can lead to side effects ranging from mild stomach upset to much more serious complications. Doctors have long dreamed of **drug delivery systems** (DDS) that could focus on one specific spot, releasing just the right amount of medicine over time. Think of it like a slow-release drip of healing directly where the body needs it most. Scientists have explored all sorts of carriers, tiny silica particles, metal-organic cages, carbon nanotubes, liposomes (little fat bubbles), and polymers. But one of the most versatile candidates is something called **electrospun fibers**. ### What exactly are electrospun fibers? Electrospinning sounds futuristic, but the principle is simple. Picture a syringe filled with a polymer solution. When a high voltage is applied, the liquid is pulled into ultra-thin jets that solidify in mid-air, forming fibers thousands of times thinner than a human hair. These fibers can be collected into mats that look like soft, delicate fabric. **What makes them special is that you can trap drugs inside them**. And because their properties, diameter, porosity, flexibility, can be tuned, you can adjust how fast or slow the medicine seeps out. These mats **could be used as wound dressings**, coatings for medical implants, scaffolds for tissue regeneration, or even as specialized filters. The team chose **metronidazole**, a widely prescribed antibiotic used to treat infections like gum disease, rosacea, bacterial vaginosis, and post-surgical infections. While effective, the drug often causes unpleasant side effects when taken orally or intravenously. A **localized delivery system could reduce those risks while keeping the treatment effective**. There’s another reason metronidazole is tricky: it’s poorly soluble in water. That makes it hard for the body to absorb efficiently. Encapsulating it in fibers could improve both its stability and how it’s released. To develop their bandage, the researchers worked with two types of polymers: **Polycaprolactone (or PCL) and Poly(2-vinylpyridine-co-styrene) (also calledP2VP-PS)**. The former polymer is a biodegradable, FDA-approved material already used in some medical devices. It’s flexible, hydrophobic (water-repelling), and safe inside the body. The latter one is a less common block copolymer with both water-friendly and water-resistant parts, giving it interesting versatility. They made three types of fibers, that is, PCL alone, P2VP-PS alone, and a core or shell structure, like a filled candy, with PCL in the middle and P2VP-PS as the outer shell. Using electrospinning, they created mats where the fibers were about 700–1300 nanometers thick (for comparison, a human hair is about 80,000–100,000 nanometers wide). Metronidazole was mixed in at different concentrations. And now it's time to look at their results. Microscopy showed that **the drug was evenly distributed**, with no clumps or crystals. That’s important because clumps can cause erratic drug release. Also, while normally, metronidazole forms crystals, inside the fibers, it became amorphous (non-crystalline), which can improve how easily the drug dissolves. The team found that this compound was stable over many months of storage. Furthermore, the fibers released metronidazole steadily into water in lab tests. High concentrations caused an initial “burst release” (too much drug too fast), but this was **suppressed in the core/shell designs**, where the shell slowed things down. Overall, **mathematical modeling confirmed diffusion control**: for most fibers, the release of the drug followed a predictable diffusion process, meaning it seeped out gradually rather than unpredictably. PCL mats soaked up little water, while P2VP-PS mats absorbed much more. This matters because wound dressings need to handle varying amounts of fluid from mild to heavily oozing wounds. This research can help reimagine how we heal, because electrospun mats with antibiotics could treat chronic gum infections like **periodontitis** without repeated pills, serve as **advanced wound dressings** for ulcers, bedsores, or surgical sites, protecting the area while delivering antibiotics, reduce the **risk of antibiotic resistance** by avoiding unnecessarily high systemic doses, and improve patient comfort by minimizing side effects. The best part is that, as the polymers used are biodegradable, the mats would break down naturally after doing their job. At this point, the work is still at the in vitro (lab) stage. That means the fibers were tested in controlled conditions, not yet in living organisms. The next steps would involve animal studies, and eventually clinical trials, to prove safety and effectiveness in real-world healing. But with their experiments, the research team has shown that electrospun fibers can be tuned to deliver antibiotics in a patient-friendly way. Their work also highlights the potential of combining “old” drugs like metronidazole with **new delivery technologies** to give them a second life in modern medicine. One of the biggest challenges in medicine involves rethinking treatment at the smallest scale to make the biggest difference. And what began in Kraków as a jet of polymer under high voltage may someday transform into a new standard of care, where healing is woven, quite literally, into the fabric of our treatments. If you want to learn more, read the original article titled "Electrospun Fiber Mats with Metronidazole: Design, Evaluation, and Release Kinetics" on [The Journal of Physical Chemistry] at . [The Journal of Physical Chemistry]: http://dx.doi.org/10.1021/acs.jpcb.5c00873

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