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Background: Glioma is the deadliest brain cancer in adults because the blood-brain-barrier (BBB) prevents the vast majority of therapeutic drugs from entering into the central nervous system. The development of BBB-penetrating drug delivery systems for glioma therapy still remains a great challenge. In this study, we aimed to design and develop a theranostic nanocomplex with enhanced BBB penetrability and tumor-targeting efficiency for glioma single-photon emission computed tomography (SPECT) imaging and anticancer drug delivery., Results: This multifunctional nanocomplex was manufactured using branched polyethylenimine (PEI) as a template to sequentially conjugate with methoxypolyethylene glycol (mPEG), glioma-targeting peptide chlorotoxin (CTX), and diethylenetriaminepentaacetic acid (DTPA) for 99m Tc radiolabeling on the surface of PEI. After the acetylation of the remaining PEI surface amines using acetic anhydride (Ac 2 O), the CTX-modified PEI (mPEI-CTX) was utilized as a carrier to load chemotherapeutic drug doxorubicin (DOX) in its interior cavity. The formed mPEI-CTX/DOX complex had excellent water dispersibility and released DOX in a sustainable and pH-dependent manner; furthermore, it showed targeting specificity and therapeutic effect of DOX toward glioma cells in vitro and in vivo (a subcutaneous tumor mouse model). Owing to the unique biological properties of CTX, the mPEI-CTX/DOX complex was able to cross the BBB and accumulate at the tumor site in an orthotopic rat glioma model. In addition, after efficient radiolabeling of PEI with 99m Tc via DTPA, the 99m Tc-labeled complex could help to visualize the drug accumulation in tumors of glioma-bearing mice and the drug delivery into the brains of rats through SPECT imaging., Conclusions: These results indicate the potential of the developed PEI-based nanocomplex in facilitating glioma-targeting SPECT imaging and chemotherapy.

This study was to investigate the synthesis and biological evaluation of [99mTc]Tc-labeled Buthus martensii Karsch Chlorotoxin ([99mTc]Tc-BmK CT) as a radiopharmaceutical for glioma single photon computed emission tomography (SPECT) imaging. The results showed that BmK CT peptide modified with a hexahistidine tag displayed good cytocompatibility in vitro, and could be efficiently radiolabeled with 99mTc via [99mTc]Tc-tricarbonyl chemistry. The [99mTc]Tc-BmK CT showed satisfactory radiochemical purity and stability in vitro, and could be developed as a probe for targeted SPECT imaging of glioma cells in vitro and in a tumor-bearing mouse model. Our data indicated that the synthesized [99mTc]Tc-BmK CT might be developed as a promising imaging agent for glioma diagnostic application. [ABSTRACT FROM AUTHOR]