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A comparative study has been done on the drug loading efficacy of different surface functionalized Fe3O4 magnetic nanoparticles (MNP) and their effect toward ovarian cancer cell line (HeLa) in vitro. The surface coating was done with carboxyl group enriched organic ligands such as succinic acid, L-arginine, oxalic acid, citric acid and glutamic acid. A maximum of similar to 62 wt.% drug has been loaded in oxalic acid coated MNP whereas least (similar to 35 wt.%) in arginine coated MNP due to variation in the chemistry of surface active agents. The cytotoxicity of functionalized MNP and doxorubicin loaded MNP were studied. The functionalized MNP are quite biocompatible whereas they show cytotoxic effect in HeLa cells e.g., around 35% cell death when treated with oxalic acid coated MNP at a concentration of similar to 100 mu g/ml. The cell death was triggered in drug loaded particle and almost complete cell death i.e., >90% was observed in oxalic acid coated MNP followed by similar to 80% and similar to 70% death in arginine and succinic acid coated MNP, respectively.

Designing bioresponsive nanocarriers for controlled and efficient intracellular drug release for cancer therapy is a major thrust area in nanomedicine. With recent recognition by the US FDA as a safe material for human trials, mesoporous silica nanoparticles (MSNPs) are being extensively explored as promising theranostic agents. Green fluorescent carbon quantum dots (CQDs), though known as possible alternatives for their more toxic and relatively less efficient predecessors, are less known as gate keepers for drug release control. We report for the first time an efficient bioresponse of CQDs when judiciously designed using glutathione cleavable (redox responsive) disulphide bonds. When the anticancer drug doxorubicin loaded MSNPs are capped with these CQDs, they display promising drug release control on exposure to a mimicked intracellular cancer environment. Their dual functionality is well established with good control on preventing the premature release and exceptional bio-imaging of HeLa cancer cells. Fluorescence images prove selective targeting of HeLa cells by overexpression of folate receptors from the surface functionalised folic acid ligand. Extensive characterisation using XRD, TEM, BET analysis, drug loading tests, drug release kinetics, MTT assay and fluoroscence cell imaging helps in understanding the multi-functionalities of the successful design, extending its scope with exciting prospects towards non-invasive targeted drug delivery and bio-imaging for effective cancer diagnosis and treatment.