Glioblastoma (GBM) remains one of the most lethal cancers due to its high recurrence rates after surgical resection, radiotherapy and systemic chemotherapy. Medical-grade graphene oxide (GO) with its large surface area available for bioactive molecule loading, high dispersibility in biological fluids, and biocompatibility serves as a promising carrier platform for medical use. This thesis explores novel 2D nanoscale platforms, using different approaches that could enhance localized immunomodulation and immunotherapy treatments. The first part of the thesis focuses on the development of GO flat-shaped, thin nanosheet platforms as complexes with immunomodulating small molecules. GO nanosheets were non-covalently complexed with resiquimod (R848), a synthetic and clinically approved (not for oncology applications) TLR7/8 agonist, yielding stable flat-shaped nanoconstructs for intratumoral administration. Physicochemical characterization confirmed successful complexation, while biological studies in a GL261 mouse model explored immunomodulation via macrophage reprogramming. The R848 molecule preserved its bioactivity after complexation with the GO nanosheets, effectively reprogrammed M2-like to M1-like macrophages, and inhibited tumor growth via modulation of the tumor microenvironment. Building on this, a cancer nanovaccine platform was then designed by incorporating GBM cell (GL261) lysate onto GO and GO:R848 nanosheets, followed by thorough physicochemical and colloidal analysis. The developed platform successfully loaded GBM-derived antigens and R848, displaying robust physicochemical and colloidal stability, selective protein interaction, and promising potential for immune activation, pending further in vivo validation. Next, the engineering of localized technologies aiming to eliminate remaining tumor cells post-resection is described. FDA-approved (for wound healing use) fibrin gels were explored in two strategies: a) as sealants of the GO nanosheet platforms; and b) as matrices for local delivery of the GO nanosheet platforms in the resection marginal zone. Gel systems were fully characterized in terms of mechanical, morphological and physicochemical properties. Proof-of-concept biological investigations in a GL261 post-resection mouse model were performed. Fibrin gels proved effective as intracavitary sealants, retaining GO nanosheets at the post-resection site and preventing washout, offering a promising platform for local post-surgical immunotherapy. In contrast, when used as delivery matrices, the gels failed to release GO into surrounding tissue, making them unsuitable for controlled nanosheet release. Finally, the GO nanosheet surface properties were engineered using coatings to enhance tissue diffusion and adhesion, and tested in a brain phantom model. Sprayable strategies were explored in parallel, to improve GO deposition within the GBM post-resection cavity. Surface-coated GO demonstrated effective adhesive and diffusive properties in brain phantoms, suggesting a viable strategy to enhance GO nanosheet retention in the post-resection cavity, especially when paired with spray delivery, which enabled a uniform and controlled material deposition. Overall, this thesis explored different approaches in the design and characterization of GO nanosheet platforms aimed at improving GBM therapeutic use by enhancing tissue immunomodulation in bulk and post-surgical resection.
Engineering of graphene oxide-based hybrids as platforms for glioblastoma therapy
Despotopoulou, D. (Author). 4 Sept 2025
Student thesis: Doctoral thesis
Student thesis: Doctoral thesis