Core-shell structured polypyrrole/mesoporous SiO2 nanocomposite capped with graphene quantum dots as gatekeeper for irradiation-controlled release of methotrexate

Abstract A core-shell structured nanocomposite of polypyrrole/mesoporous SiO 2 (PPy/mSiO 2 ) is rationally designed as the nanocarrier for methotrexate (MTX), a chemotherapeutic drug for cancer treatment. Graphene quantum dots (GQDs) are introduced to the outer surface of PPy/mSiO 2 , and it functions as a gatekeeper for the loaded MTX through the formation of H-bonds with the functionalized mSiO 2 . In the proposed nanocarrier for MTX, the mesopores in mSiO 2 are beneficial for the accommodation of MTX, resulting in enhanced encapsulation capacity of the nanocarrier; on the other hand, PPy can effectively convert the near-infrared (NIR) light to heat. Under the irradiation of NIR light, the H-bonds between GQDs and mSiO 2 are broken due to the gradually increased temperature, and therefore the GQDs cap is removed and consequently the encapsulated MTX is released from the nanocarrier. In this study, NIR irradiation-controlled drug delivery is achieved successfully owing to the synergistic effects of PPy, mSiO 2 and GQDs, which opens a new window for the construction of smart drug delivery systems.