The established treatment of primary brain tumors includes an initial tumor resection in a surgical procedure using fluorescence-supported tumor tissue visualization . For this purpose, the patient is administered a fluorescent dye, capable of passing the disrupted blood-brain-barrier that selectively accumulates in the cancerous tissue. Precise tumor removal is then aided by the use of intermittent dyespecific illumination, which allows better contrast between healthy and cancerous brain tissue . The application of 5-aminolevulinic acid (5-ALA), as a precursor dye, is currently considered the gold standard for primary brain tumor surgery . This molecule exhibits high water-solubility, which facilitates its implementation as pharmaceutical formulation, and thus its administration to the patient. After accumulating in the brain tumor, 5-ALA is enzymatically transformed into Protoporphyrin IX (PPIX) , which is the fluorophore used for tumor visualization. The brain tumor surgery is followed by radiochemotherapy to reduce residual tissue and thus improve the overall tumor removal . However, these therapies do not selectively affect cancerous tissue and result in collateral damage of healthy, surrounding brain cells.