Nanodiamonds with Surface Grafted Polymer Chains as Vehicles for Cell Imaging and Cisplatin Delivery: Enhancement of Cell Toxicity by POEGMEMA Coating

Nanodiamonds (NDs) are highly promising drug carriers due to their biocompatibility, manipulable surface chemistry, and nonbleaching flourescence. In this communication, we compare the cytotoxicity of three ND-cisplatin systems in which cisplatin was incorporated via direct attachment to the ND surface, physical adsorption within a poly(oligo(ethylene glycol) methyl ether methacrylate) POEGMEMA surface coating, or complexation to 1,1-di-tert-butyl 3-(2-methacryloyloxy)ethyl)butane-1,1,3-tricarboxylate (MAETC) groups of a POEGMEMA-st-PMAETC surface layer. The polymer layers were introduced by grafting from RAFT-functionalized ND particles. All three ND systems displayed lower IC50 values than free cisplatin in A2870 and A2870cis ovarian cancer cells. The two polymer-containing systems outperformed their naked counterpart, with the POEGMEMA-coated particles the most cytotoxic, displaying an IC50 of 1.5 mu M, more than an order of magnitude lower than that of cisplatin. The enhanced cytotoxicity is attributed to promotion of cellular uptake by the hydrophilic surface polymer.