Influencing Factors on the Degradation of PLA‐SPION Markers for Medical Devices in Magnetic Imaging Modalities—An In Vitro Study

Polylactic acid (PLA), with its degradable characteristics, is a versatile polymer used for various application scenarios. Coating medical instruments with a composite of PLA and superparamagnetic iron‐oxide nanoparticles (SPIONs) allows for their visualization in Magnetic Particle Imaging and Magnetic Resonance Imaging, which could enable functional diagnostics in medicine. This study investigates the influencing factors on the degradation of PLA‐SPION markers. The influence of the SPION mass fraction, surrounding medium/pH, carrier material, and initial coating mass on the hydrolytic degradation is monitored at 37°C for up to 4 weeks. It is shown that the addition of SPIONs generally decreases the degradation rate compared to neat PLA. However, within the composites, a higher SPION mass fraction increases the degradation rate. The markers degrade relatively quickly at a physiological pH of 7.4, while a more acidic environment reduces the degradation rate. A lighter initial coating mass also facilitates degradation, while the carrier material seems to have a marginal effect on the degradation rate. These results allow for a better understanding of the influencing factors on the degradation of PLA‐SPION markers and support the feasibility of functional imaging with these markers.