Synthesis and characterization of SPIONs@APTES conjugated with chlorin E6 via carbodiimide for photodynamic therapy

Abstract Glioblastoma multiforme is one of the most aggressive primary brain tumours and remains highly resistant to conventional therapeutic approaches. Photodynamic therapy has emerged as a promising alternative. However, the clinical application of many photosensitisers is limited by low stability, poor solubility, and non-specific distribution in biological systems. In this study, iron oxide nanoparticles (SPIONs) were synthesised by a coprecipitation method and subsequently functionalised with 3-aminopropyltriethoxysilane (APTES) to enable the conjugation of the photosensitiser Chlorin E6 (Ce6). The resulting SPIONs@APTES–Ce6 nanoprobes were characterised using dynamic light scattering, Zeta Potential analysis, UV–Vis spectroscopy, fluorescence spectroscopy, and Fourier Transform infrared spectroscopy, confirming successful surface functionalisation and preservation of the photophysical properties of Ce6. The photodynamic activity of the nanoprobes was evaluated in vitro using the M059J glioblastoma cell line. Cell viability was assessed through complementary assays, including MTT, Trypan Blue exclusion, and resazurin reduction. The nanoprobes exhibited low dark cytotoxicity under the tested conditions. Upon light activation at 660 nm, a significant reduction in cell viability was observed, demonstrating effective photodynamic activity. These findings suggest that SPIONs@APTES–Ce6 nanoprobes may represent a potential nanostructured platform for further investigation in glioblastoma photodynamic therapy.