Advancing Phototherapies in Glioblastomas: Plasma Membrane Damage by Single-Point Laser Irradiation Using Clinical Cancer Markers.

Purpose: This study aimed to present a novel phototherapeutic approach by inducing plasma membrane damage and cell death in glioblastoma cells using single-point laser irradiation rather than larger area irradiation. Methods: Glioblastoma cells were cultured in 2D monolayers and 3D spheroid models. Fluorescent markers like 5-aminolevulinic acid (5-ALA), the precursor of Protoporphyrin IX (PPIX), and Sodium Fluorescein (NaF) aid in tumor visualization during surgery are being explored for photodynamic therapy (PDT). 5-ALA and NaF were applied to induce PPIX production or dye uptake, respectively. Fluorescence microscopy confirmed dye localization—PPIX on the plasma membrane and NaF in the extracellular space. Cells were irradiated with a focused laser, and the resulting plasma membrane damage was assessed through viability assays and membrane integrity markers. Cell death was quantified in both monolayers and spheroids. Results: PPIX was localized on the plasma membrane, while NaF remained in the extracellular space, contacting the membrane. Single-point laser irradiation induced plasma membrane disruption in both conditions, resulting in selective cancer cell death. Both dyes led to significant cell death, even at the center of spheroids, demonstrating the effectiveness of this method in 3D structures. Conclusions: This study presents a novel approach using focused laser irradiation and clinically approved dyes to induce precise, targeted cell death in glioblastoma models, suggesting a promising potential for theranostic applications in tumor eradication.