Tunable doxorubicin release from polymer-gated multiwalled carbon nanotubes

Two pH and temperature controlled drug delivery systems for cancer therapy are here reported by using vapour phase and liquid phase functionalized multiwalled carbon nanotubes (MWCNT). Both oxidized MWCNT were functionalized at the carboxyl groups with a short hydrophilic polyethylene glycol (PEG) chain. The nanosystems were loaded with doxorubicin and covered with the biocompatible polymer polylactide, able to form hydrogen bonding with PEG and to entrape the drug inside the two polymeric chains. The different oxidative reaction conditions of MWCNT have demonstrated to deeply affect their agglomeration ability and the available reactive surface area for drug loading which in turn, affected the drug release abilities of the synthesized polymer-gated drug delivery systems. The in vitro release abilities as well as their antiproliferative effect on three different human cancer cell lines were evaluated and compared, highlighting the possibility to tune the amount of drug released by controlling the functionalization degree of the carbon nanotube based material. Biological tests highlighted the high biocompatibility of both systems and their ability to deliver doxorubicin to cancer cells.