Evaluation of cerium release and antioxidant effect in electrospun polycaprolactone/gelatin scaffolds for articular cartilage regeneration

Abstract

Introduction: Persistent inflammation and oxidative stress play a critical role in the progression of articular cartilage damage and significantly impair its regenerative capacity. In this context, cerium oxide nanoparticles (CeO₂ NPs) have attracted considerable attention due to their ability to scavenge reactive oxygen species (ROS) and mitigate oxidative stress. Their antioxidant activity is attributed to the coexistence of Ce³⁺ and Ce⁴⁺ oxidation states on their surface, allowing them to reversibly switch between both states and mimic the activity of antioxidant enzymes such as superoxide dismutase and catalase. Incorporating these nanoparticles into electrospun scaffolds may provide biomaterials capable of offering structural support while simultaneously exerting sustained antioxidant activity within the local microenvironment.

Objective: To evaluate cerium release from electrospun polycaprolactone/gelatin scaffolds containing different concentrations of cerium oxide nanoparticles and to determine their ability to modulate cellular oxidative stress.

Methodology: Electrospun polycaprolactone/gelatin scaffolds containing different concentrations of cerium oxide nanoparticles (1, 2, 4, 7, and 10 wt.% relative to polycaprolactone) were fabricated. Cerium release was evaluated at different incubation times using inductively coupled plasma mass spectrometry (ICP-MS). In parallel, the antioxidant capacity of the scaffolds was assessed through reactive oxygen species (ROS) kinetic studies in cell cultures subjected to oxidative stress. Intracellular superoxide production was induced using antimycin A, an inhibitor of mitochondrial respiratory chain complex III, and quantified with dihydroethidium (DHE). The obtained data were used to compare the performance of the different formulations and to establish the relationship between nanoparticle concentration, cerium release, and biological response.

Results: ICP-MS analysis confirmed cerium release from the scaffolds into the surrounding medium, with release profiles varying according to the initial nanoparticle concentration. ROS kinetic studies revealed that scaffolds containing lower nanoparticle concentrations (1 and 2 wt.% CeO₂) exhibited superior antioxidant performance, reducing intracellular oxidative stress more effectively than formulations with higher CeO₂ content. These findings suggest that antioxidant activity is not exclusively dependent on nanoparticle loading, but also on their availability and behavior within the scaffold system.

Conclusions: Electrospun scaffolds containing cerium oxide nanoparticles demonstrated the ability to release cerium and modulate cellular oxidative stress. Formulations with lower nanoparticle concentrations exhibited the most favorable performance, suggesting the existence of an optimal concentration range for maximizing antioxidant effects. These findings highlight the importance of nanoparticle dose optimization in scaffold design. Ongoing studies are focused on surface functionalization with extracellular matrix proteins to enhance cell-material interactions and further improve the regenerative potential of the scaffolds.