Preparation, characterization and preliminary cytotoxic evaluation of 6-mercaptopurine-coated biotinylated carbon dots nanoparticles as a drug delivery system

In the treatment of acute lymphoblastic leukemia, 6-mercaptopurine (6-MP) is commonly used. Yet, short half-life in plasma, poor water solubility, severe side effects and variable bioavailability limit its use. GSH-responsive prodrugs (3&5) and biotin receptor targeted were made to enhance the intracellular accumulation related to 6-MP in the cancer cell. In compound 5, nanoparticles (NPs) have been prepared through conjugating 6-MP to carbon dots (nanocarriers) through GSH-sensitive carbonyl vinyl sulfide linkage, and surface decoration with biotin. Compound 3 was synthesized by direct conjugation of 6-MP to the biotin through GSH-sensitive linkage. In-vitro drug release study of NPs showed good stability in the phosphate buffer saline (PBS), which contains 100 µM GSH at (pH 7.40). Yet, the cumulative rate of the drug release that is associated with samples that contain the GSH medium of 10 mM reached 79.6% in acetate buffer at (pH 5.8). In vitro cytotoxicity study (MTT assay) demonstrated that compound 3 showed higher inhibition ratios on biotin receptor overexpressed cell lines (MCF-7, HepG2) and lower cytotoxicity on normal cell lines (CHO). Compound 5 showed good activity, comparable to 6-MP against (MCF-7, HepG2), and much lower cytotoxicity on (CHO).