UCN-SiO 2 -GO: a core shell and conjugate system for controlling delivery of doxorubicin by 980 nm NIR pulse.

Herein, graphene oxide (GO) has been attached with core-shell upconversion-silica (UCN-SiO 2 ) nanoparticles (NPs) to form a GO-UCN-SiO 2 hybrid nanocomposite and used for controlled drug delivery. The formation of the nanocomposite has been confirmed by various characterization techniques. To date, a number of reports are available on GO and its drug delivery applications, however, the synergic properties that arise due to the combination of GO, UCNPs and SiO 2 can be used for controlled drug delivery. New composite UCN@SiO 2 -GO has been synthesized through a bio-conjugation approach and used for drug delivery applications to counter the lack of quantum efficiency of the upconversion process and control sustained release. A model anticancer drug (doxorubicin, DOX) has been loaded to UCNPs, UCN@SiO 2 NPs and the UCN@SiO 2 -GO nanocomposite. The photosensitive release of DOX from the UCN@SiO 2 -GO nanocomposite has been studied with 980 nm NIR laser excitation and the results obtained for UCNPs and UCN@SiO 2 NPs compared. It is revealed that the increase in the NIR laser irradiation time from 1 s to 30 s leads to an increase in the amount of DOX release in a controlled manner. In vitro studies using model cancer cell lines have been performed to check the effectiveness of our materials for controlled drug delivery and therapeutic applications. Obtained results showed that the designed UCN@SiO 2 -GO nanocomposite can be used for controlled delivery based therapeutic applications and for cancer treatment.