Polydopamine-carbon dots functionalized hollow carbon nanoplatform for fluorescence-imaging and photothermal-enhanced thermochemotherapy.

The low power photothermal therapy can reduce the tissue damage caused by laser irradiation, thus the near-infrared (NIR) absorbing vehicles with high photothermal conversion efficiency are demanded in the low power treatment. Herein, the NIR-absorbing agent polydopamine (PDA) and carbon dots (CDs) were gated on the openings of hollow mesoporous carbon (HMC) to construct a photothermal enhanced multi-functional system (HMC-SS-PDA@CDs). Interestingly, the fluorescence emission wavelength of HMC-SS-PDA@CDs was red-shifted by FRET effect between PDA and CDs, which solved the dilemma of fluorescence quenching of carbon-based materials and was more conducive to cell imaging. The modification of PDA@CDs not only acts as the gatekeepers to realize multi-responsive release of pH, GSH and NIR, but also endows the HMC vehicle with excellent photothermal generation capacity, the possibility for bio-imaging as well as the enhanced stability. Naturally, both the cytological level and the multicellular tumor sphere level demonstrate that the delivery system has good low-power synergistic therapeutic with combination index (CI) of 0.348 and imaging effects. Meanwhile, the combined treatment group showed the highest tumor inhibition rate of 92.6% at 0.75 W/cm2. Therefore, DOX/HMC-SS-PDA@CDs nano-platform had broad application prospects in low power therapy and convenient imaging of carbon-based materials.