Influence of PEG Molecular Weight on the Drug Release and In vitro Cytotoxicity of Single-Walled Carbon Nanotubes-PEG-Gemcitabine Conjugates

Background: Gemcitabine (GEM) is a highly hydrophil anticancer drug which extensively used in the clinic for the treatment of a range of solid tumors, including pancreatic and lung cancers. We have designed a drug delivery system based on single-walled carbon nanotubes (SWCNTs) for the anticancer drug GEM, which has limitations under biological conditions, by using polyethylene glycol (PEG) to obtain nanoconjugates with high loading capacity, controlled drug release and effective cytotoxicity. Methods: Raw SWCNTs were functionalized through carboxylation, acylation, PEGylation and finally GEM conjugation via a cleavable ester bond. Different characterization techniques such as Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance spectrometer (NMR) and differential scanning calorimetry analysis (DSC) were performed to confirm the successful functionalization. Next, the influence of molecular weight (MW) of PEG on the drug loading capacity, drug release and cytotoxicity was studied. Results: Experimental results showed that the drug loading capacity was dependent on the MW of PEG, but the drug release was independent. Also, the results revealed that the nanoconjugates with lower PEG MW caused higher cytotoxicity in A549 and MIA PaCa-2 cancer cells. Conclusion: Our studies indicated which of PEG MWs could be useful for this drug delivery system.