Folate-conjugated nanodiamond for tumor-targeted drug delivery

An effective drug delivery system based on functionalized nanodiamond (ND) is constructed by layer-by-layer synthesis. Initially, ND is modified with PEG-diamine and conjugated with folate (FA) to obtain a ND-PEG-FA (NPF) nanocarrier. Then, doxorubicin (DOX) is physically attached to the NPF nanocarriers to prepare the drug system (ND-PEG-FA/DOX, NPFD), which exhibits excellent stability under neutral pH conditions, and releases large amounts of DOX in acidic extracellular fluids (pH 6.5 or pH 5.5). Relying on the role of folate and folate receptors, NPFD nanoparticles tend to discriminate between tumor cells and normal cells and enter the cells by clathrin-dependent and receptor-mediated endocytosis. Interestingly, an MTT assay found that the NPFD nanoparticles not only demonstrated a slow and sustained drug release profile, but also had tumor-targeted toxicity. This implies that the NPFD system is capable of targeted drug delivery and can act as a nanodrug with promising chemotherapeutic efficacy and safety.