MGMT and glioblastoma: Theproduction of the TMZ+BTZ PLGA NPs was optimized by experimentaldesign, and to further increase the brain targeting ability of theproposed NPs, these were conjugated with transferrin (Tf) since theTf receptor (TfR) is overexpressed in the blood–brain barrier(BBB) and GBM cells.19,20 After physicochemical characterization,the therapeutic effect of the developed NPs was evaluated by usinghuman GBM cells with different MGMT expressions.