Glucosamine-conjugated graphene quantum dots as versatile and pH-sensitive nanocarriers for enhanced delivery of curcumin targeting to breast cancer.

Applying multifunctional nanocarriers, comprising specifically traceable and tumor targeting moieties, has significantly increased in cancer theranostics. Herein, a novel targeted, trackable, and pH-responsive drug delivery system was fabricated based on glucosamine (GlcN) conjugated graphene quantum dots (GQDs) loaded by hydrophobic anticancer agent, curcumin (Cur), to evaluate its targeting and cytotoxicity potential against breast cancer cells with overexpression of GlcN receptors. The biocompatible photoluminescent GQDs were synthesized from graphene oxide through the green and facile oxidizing method. The structural and spectral characterizations of the as-prepared GQDs and Cur/GlcN-GQDs were investigated. The GQDs sizes were within 20-30 nm and showed less than ten layers. A pH-sensitive and sustained release behavior was also observed for the Cur loaded nanocarrier with a total release of 37% at pH 5.5 and 17% at pH 7.4 after 150 h. In vitro cellular uptake studies through fluorescence microscopy and flow cytometry exhibited stronger fluorescence for the targeted nanocarrier against MCF-7 cells compared to the non-targeted one, owing to higher cellular internalization via GlcN receptor-mediated endocytosis. Furthermore, the MTT assay results demonstrated the nontoxicity of the bare nanocarrier with the cell viability of above 94% even at concentrations as high as 50 μg·ml, while the Cur/GlcN-GQDs exhibited much more cytotoxicity against MCF-7 cells compared to Cur/GQDs. It is reasonable to conclude that this advanced multifunctional nano-assembly offers superior potential for breast cancer cell-targeted delivery.