Thermo-sensitive graphene oxide–polymer nanoparticle hybrids: synthesis, characterization, biocompatibility and drug delivery

We report the covalent interaction mediated assembly of thermo-sensitive polymer nanoparticles (PNPs) on functionalized graphene oxide (GO) nanosheets to create novel GO-PNP hybrids for drug delivery. To this end, thermo-sensitive PNPs with an average diameter of about 50 ± 12 nm were first synthesized with the free radical polymerization reaction, and GO nanosheets were noncovalently modified with a bifunctional linker to provide reactive sites for the binding of PNPs. Finally, GO-PNP hybrids were successfully synthesized by the covalent interaction mediated assembly of PNPs on GO nanosheets. Multi-characterization techniques were utilized to identify the formation of PNPs, the modification of GO nanosheets, and the formation of GO-PNP hybrids. Cell culture experiment with the mouse osteoblast-like MC3T3-E1 cells indicates that the synthesized GO-PNP hybrids have satisfactory biocompatibility. The loading efficiency of drug molecules (Adriamycin, ADR) with GO-PNP (∼87%) is close to that with GO (∼91%), but significantly higher than that with PNPs (∼46%). The release efficiency of GO-PNP hybrids with the highest surface coverage of PNPs (∼85 PNPs per μm2) is about 22%, which is very close to that of PNPs (∼25%) and significantly higher than that of GO (∼11%). Our study indicates that this thermo-sensitive GO-PNP hybrid, when considering the drug loading and release comprehensively, has better performance than both PNPs and GO and thus can be used as a novel nanocarrier for temperature-controllable drug release. The GO-PNP hybrids with and without ADR were applied to kill cancer cells in vitro and the result shows that the GO-PNP hybrid with ADR has an obvious effect on killing cancer cells, and its performance is obviously better than both GO and PNPs. It is expected that this new hybrid material based on GO and PNPs will have great potential for in vivo applications such as to kill target cancer cells by modifying with specific antibodies.