CLUSTER OF CARBON NANOSPHERES AS DRUG CARRIER

Abstract

Cluster of carbon nanospheres, or the so called oxidized carbon nanospheres (OCSs) were successfully synthesized. The use of OCSs as drug carrier was, then, investigated by comparison to the different shaped oxidized carbon particulates, oxidized carbon nanotubes (OCTs) and oxidized graphene sheets (OGShs). The result reveals that OCSs possessed highest ability to associate with lipid bilayer membrane and highest level of penetration into cell-sized liposomes, whereas OCTs showed the moderate adhesion with lipid membrane without liposome penetration and OGShs exhibited no adhesion to the membrane. Regarding lipid composition of the membrane, the OCSs more preferably adhere on the liquid-disordered (Ld) membrane (composes of high fluidity lipid molecules) as compared to the liquid-ordered (Lo) membrane (composes of less fluid lipid molecules), owning to the more favorable free energy of membrane curvature. OCSs could effectively deliver cargo, here curcumin was used as model cargo, into A549 lung cancer cells and allowed accumulation of curcumin in both cytoplasm and nucleus of the cells. OCTs could induce only moderate uptake of curcumin into the cytosol of the cells, whereas OGShs were rarely internalized into cells. Surface modification of oxidized carbon particulates by mPEG decreases their ability to associate with lipid bilayer membrane. In addition, the OCSs could deliver both hydrophobic and hydrophilic anti-cancer drugs into cancer cells, A549 and A549RT-eto. The results reveal that delivering of paclitaxel, which is a hydrophobic drug, by OCSs showed anti-cancer activity at the same level as use of the free drug in DMSO. This could be implied that delivery by OCSs improve cellular uptake ability of the water insoluble drug and avoid use of organic solvent.