Sodium hydroxide (naoh)

β-Galactosidase and the EDC required for the conjugation were purchased from MP Biomedicals (Irvine, CA, USA). Gel-like CDs were synthesized in the lab. For the synthesis of CDs, citric acid (99.5–100%) was purchased from VWR (Radnor, PA, USA), and EDA (99%) and quinine hemisulfate monohydrate from Alfa Aesar (Tewksbury, MA, USA). Hydrochloric acid, Sodium chloride (99%) and sodium hydroxide were obtained from MP Biomedicals (Irvine, CA, USA). Compressed argon gas with ultra-high purity (99.99%) was procured from Airgas (Radnor, PA, USA).

The day after post-treatment dynamic MRI, rats received 12.5 μCi of ¹⁴C-AIB (MW = 103 Da; American Radiolabeled Chemicals, St. Louis MO, USA) administered IV for assessment of unidirectional tracer leakage from the blood to brain tissue. A serum sample was collected 10 min after AIB administration followed by perfusion to clear the vasculature. The brains were harvested and four regions were dissected: tumor mass, tissue 1–2 mm brain around tumor (BAT), tissue 1–2 mm ipsilateral brain distant to tumor (BDT), and contralateral left hemisphere (LH) normal brain tissue. Each tissue sample was weighed, solubilized in 2 ml of sodium hydroxide overnight (MP Biomedicals, Solon, OH, USA) and radioactivity was determined by liquid scintillation counting in 20 ml of CytoScint ES (MP Biomedicals, Solon, OH, USA). Results were measured as percent injected dose normalized to 1 g of tissue.