Scientists from the AGH University of Science and Technology in Kraków and the Jagiellonian University found that the collagen-chitosan hydrogel, enriched with superparamagnetic iron oxide nanoparticles (SPIONs), strongly absorbs water, is non-toxic to bone-forming cells and responds to a static magnetic field. The findings were published in the journal Sustainable Materials and Technologies.

The researchers say the material could serve as a scaffold for bone tissue engineering—a temporary structure that fills bone defects and provides an environment in which cells can attach, survive, multiply and gradually rebuild damaged tissue.

Unlike permanent implants, tissue-engineering scaffolds are designed to degrade over time as new bone forms. To be effective, they must match the shape of the defect, retain water, remain non-toxic and break down in a controlled manner.

The hydrogel developed by the team consists of the naturally occurring biopolymers collagen and chitosan, combined with SPIONs—iron oxide nanoparticles that become magnetised when exposed to a magnetic field but lose their magnetism once the field is removed.

According to the researchers, the nanoparticles could make it possible to influence bone regeneration using a non-invasive external magnetic field. Previous studies have shown that static magnetic fields can affect the proliferation, migration and differentiation of cells involved in bone formation.

To evaluate the material, the team examined whether it was stable, flexible, highly hydrated and compatible with living cells. Using nuclear magnetic resonance techniques, they analysed how water behaved within the hydrogel, providing insight into its internal structure, porosity and stiffness.

The hydrogels could be moulded into different shapes without losing their structural integrity and absorbed between 10,000 and 13,000 percent of their weight in water after 24 hours in a buffer solution.

The researchers said this high water-binding capacity is important because it influences nutrient transport, the environment surrounding cells and the scaffold's rate of degradation, which varied depending on its composition.

Initial biological tests using MG-63 osteoblast-like cells, commonly used in bone regeneration research, found that adding magnetic nanoparticles did not reduce cell viability or prevent cells from attaching to the hydrogel surface. After three days, cells were growing on all of the tested materials, with no evidence of toxic effects from the nanoparticles.

The researchers then exposed the magnetic hydrogels to a static magnetic field and found that both the nanoparticles and the magnetic field influenced cell numbers and the expression of proteins associated with cell proliferation and differentiation. The effects were most pronounced after seven days of cell culture.

The team cautioned that the findings are preliminary and require further investigation, including longer-term cell culture studies, analysis of the underlying molecular mechanisms and testing under more complex biological conditions.

However, the results suggest that future bone scaffolds could do more than simply fill defects, instead actively responding to external stimuli to create conditions that encourage new bone tissue to form. (PAP)

PAP - Science in Poland

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