Development of cRGD-Functionalized Fe3O4 Nanoparticles for Glioblastoma Targeting and Evaluation of Magnetic Hyperthermia Using a Planar Coil in Tumor Spheroids

Background/Objectives: Glioblastoma multiforme (GBM) is the most aggressive primary tumor of the central nervous system and remains associated with poor prognosis despite current therapies. Magnetic hyperthermia (MHT) mediated by superparamagnetic iron oxide nanoparticles (SPIONs) is a promising therapeutic approach; however, improvements in tumor targeting, colloidal stability, and translational applicability are still needed. This study aimed to develop dopamine-functionalized SPION conjugated with the cyclic cRGD peptide (SPION-DOPA/cRGD) to promote preferential association with GBM cells and evaluate their physicochemical properties, cellular affinity, and therapeutic performance for MHT using a planar coil system. Methods: SPIONs were synthesized by thermal decomposition, functionalized with dopamine, and conjugated with cRGD. Their morphological, structural, magnetic, colloidal, and magnetothermal properties were characterized. Cellular affinity was evaluated in U87MG and HUVECs by Prussian Blue staining and Inductively Coupled Plasma Mass Spectrometry (ICP-MS), and free-cRGD competition was used to assess RGD–integrin-mediated association. Biocompatibility and therapeutic efficacy were assessed by bioluminescence assays in U87MG spheroids following MHT. Results: SPION-DOPA/cRGD exhibited quasi-spherical morphology, cores below 10 nm, superparamagnetic behavior, and relatively consistent hydrodynamic diameters over 120 min in both water and DMEM/F12. The cRGD-containing formulation exhibited enhanced cellular association with U87MG cells while maintaining low interaction with HUVECs; free-cRGD competition reduced nanoparticle association, supporting RGD–integrin interactions. Under a 300 G field, nanoparticles reached 42–45 °C, with a specific absorption rate of 210 ± 19 W g−1. The nanoformulation showed low cytotoxicity from 20 to 5000 μg Fe mL−1, with viability above 96%. SPION-DOPA/cRGD-mediated MHT reduced U87MG spheroid viability to 14.76 ± 1.02%, whereas AMF alone did not affect viability compared with controls. Conclusions: SPION-DOPA/cRGD combines preferential cellular association with U87MG cells, efficient magnetic heating, and a substantial reduction in spheroid viability in a three-dimensional tumor model. Together with a planar coil, these findings support the translational potential of this nanoplatform for preclinical MHT applications in GBM.