Self-assembled Janus graphene nanostructures with high camptothecin loading for increased cytotoxicity to cancer cells

The sequential functionalization of graphene (Gr) with oleylamine (ODA) and diethanolamine (DEA) was performed to produce amphiphilic Janus-type graphene nanosheets (DEA- f -Gr- f -ODA). The Janus graphene was self-assembled in 3D superstructures with hydrophilic external surface and hydrophobic internal space. The DEA- f -Gr- f -ODA nanoparticles were investigated as platforms for the hydrophobic anticancer drug camptothecin (CPT). The colloidal stability, drug loading and drug release properties of the DEA- f -Gr- f -ODA nanoparticles were determined. The viability of A549 cancer cells in the presence of increasing concentrations of free CPT and blank and drug-loaded DEA- f -Gr- f -ODA nanoparticles was assessed with MTT accompanied with PI/Annexin-V apoptosis assessment with flow cytometry. The uptake of DEA- f -Gr- f -ODA nanoparticles by the A549 cells was also evaluated with flow cytometry. The hemocompatibility of DEA- f -Gr- f -ODA nanoparticles was assessed with a hemolysis assay. The Janus graphene nanoparticles could host an exceptionally large amount of CPT, achieving more than double CPT loading compared to graphene-based CPT platforms reported so far, and released it in a slow biphasic fashion. The cytotoxicity and hemolysis assays provided evidence for the biocompatibility of the DEA- f -Gr- f -ODA nanoparticles and the CPT-loaded DEA- f -Gr- f -ODA nanoparticles were more cytotoxic against a human cancer cell line than free CPT, inducing a higher degree of apoptosis to the cancer cells.