Novel Difolate Targeting Nano-Level Ultrasound Contrast Agent for Therapy of Breast Cancer Tumor Cells
ABSTRACT A new type of difolate targeting nano-level ultrasound contrast agent ((folate molecule, FOL)2-TUAs) was prepared, so as to investigate its targeted binding effect with human breast cancer mammary carcinoma cells (MCF-7) in vitro. L-2-aminoadipic acid (L-2-AD) as a branch unit was inserted at the hydroxyl end of distearoyl phosphatidylethanolamine (DISP)-PEG2000-COOH to construct a tree structure. At this time, the free hydroxyl group in the distearoyl phosphatidylethanolamine (DISP)-PEG2000-COOH structure modified the FOL with the help of N-Hydroxysuccinimide/N,N'-dicyclohexylcarbodiimide (NHS/DCC). Each 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[methoxy(polyethylene glycol)-2000] (DISP-PEG2000) connected two FOLs to generate difolate targeted nanomaterials. Nano laser particle size (PS) and Zeta potential analyzer (ZPA) were applied to analyze the physical characteristics of the material such as PS and dispersion, and the enhanced development effect in vitro was detected by the ultrasonic diagnostic instrument. Besides, the targeted binding ability of the contrast agent based on this material to folate receptor (FR) overexpressing MCF-7 cells was analyzed by flow cytometry (FCM) and fluorescence microscope. In the experiment, hydrogen-1 nuclear magnetic resonance (1H NMR) demonstrated that (FOL)2-TUAs was successfully synthesized. The surface of this material was round and uniformly distributed without aggregation. According to the relative number of FOL molecules, non-targeted nano-agent (U-TUA), monofolate targeted nano-agent (FOL-TUA), and difolate targeted nano-agent ((FOL)2-TUA) were obtained. The in vitro imaging showed that different materials exhibited enhanced imaging effects in ultrasonic diagnostic equipment. FCM and fluorescence microscopy both indicated that the difolate TUA could achieve a good binding to MCF-7 cells. Most of the nano-agents were attached to the cell membrane, surrounded by red fluorophore, namely increasing the FOL content of DISP-PEG2000 chain could enhance the targeted binding ability of tumor cells.
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