Fluorescent carbon dot gated hollow mesoporous carbon for chemo-photothermal synergistic therapy.

An efficient and intelligent nano-carrier that combines cell imaging with near infrared (NIR) light and redox dual-responsive drug delivery was successfully prepared. The hollow mesoporous carbon (HMC) nanoparticles with high photothermal conversion ability were developed to increase the drug loading efficiency and realize chemotherapy and photothermal synergetic therapy. The photo-stable and luminescent carbon dots (CDs) were prepared from branched polyethyleneimine (PEI) by hydrothermal reaction. The PEI CDs (CDPEI ) were grafted on the openings of HMC as the "gatekeepers" via disulfide units (HMC-SS-CDPEI ) to prevent the premature release of doxorubicin (DOX). In the presence of GSH, the CDPEI separated from HMC due to the breakage of disulfide bonds, thus triggering the rapid release of the encapsulated drug. In addition, the release rate of DOX could be further accelerated by NIR light irradiation due to the increased temperature which would decrease the interaction between HMC and DOX. The fluorescence of the CDPEI is quenched when being attached to the HMC, while it is recovered when the CDPEI breaking away from HMC. Hence, the fluorescent CDPEI not only act as a gatekeeper to control drug release but also play a vital role in monitoring the process of the drug delivery. The developed HMC-SS-CDPEI showed dual-responsive drug release property and could be used as visible nano-platforms for chemo-photothermal synergistic therapy.