Systematic rheological investigation of chitosan-modified magnetite-reinforced thermosensitive Pluronic F127/chitosan hybrid hydrogels.

Polymer-modified magnetite nanoparticles hold great promise for diverse biomedical applications, including drug delivery, magnetic hyperthermia, and tissue engineering. However, ensuring their long-term functionality and stability for in vivo applications remains a significant challenge. In this work, chitosan-modified magnetite nanoparticles of different concentrations (0-4% w/v) were incorporated into a Pluronic F127/chitosan thermosensitive hydrogel matrix. All hydrogel formulations exhibited a temperature-induced sol-gel transition in the range of 27-28.94 °C, with viscosity increasing with increasing temperature, confirming their thermoresponsive behaviour. Furthermore, all the hydrogels displayed non-Newtonian shear-thinning behaviour. Incorporation of 4% (w/v) chitosan-modified magnetite nanoparticles into the neat hydrogel enhanced the viscosity and yield stress by 28% and 56%, respectively. The storage modulus exceeded the loss modulus for all hydrogels across the oscillatory strain range within the linear viscoelastic region and over the entire frequency range with no crossover points, validating their structural integrity and suitability for long-term in vivo applications. Thixotropic studies revealed excellent structural recovery in these hydrogels upon removal of the applied shear stress. These rheological findings position chitosan-modified, magnetite-incorporated thermoresponsive hydrogels as a structurally resilient and stable system that exhibits both magnetic and thermoresponsive behaviour, making them suitable for multifunctional biomedical applications such as magnetic hyperthermia, targeted drug delivery, and regenerative medicine.