Doxorubicin-carboxymethyl xanthan gum capped gold nanoparticles: Microwave synthesis, characterization, and anti-cancer activity.

An ultrafast (e.g. 75 s) synthesis of carboxymethyl xanthan gum (CMXG) capped gold nanoparticles (AuNPs) (CMXG@AuNPs) was developed using microwave irradiation (MWI) method. The synthesis of AuNPs was optimized by varying CMXG amount, gold ion concentration, and MWI time. The CMXG@AuNPs exhibited a spherical shape, high crystallinity, and narrow size distribution (i.e. 8-10 nm). The electrostatic interaction-mediated the loading of doxorubicin (DOX) onto CMXG@AuNPs. The release of DOX, loaded on CMXG@AuNPs was extensive in an acidic condition but negligible at physiological pH value. The in vitro anticancer efficacy of DOX loaded on CMXG@AuNPs (i.e. DOX@CMXG@AuNPs) in the presence of an ionophore (i.e. nigericin) was about 4.6 folds higher than that of free DOX. Flow cytometry revealed that DOX@CMXG@AuNPs exhibited a higher cellular uptake under an acidic condition than free DOX. CMXG@AuNPs showed unique excellence in the pH-responsive DOX-releasing property and the cancer cell-killing capability.