Polydopamine (PDA) has been widely
used in biomedical applications
including imaging contrast agents, antioxidants, UV protection, and
photothermal therapy due to its biocompatibility, metal-ion chelation,
free-radical scavenging, and wideband absorption, but its low photothermal
efficiency still needs to be improved. In this study, we chelated
near-infrared (NIR) sensitive carbon quantum dots on the surface of
polydopamine (PDA-PEI@N,S-CQDs) to increase its near-infrared absorption.
Surprisingly, although only 4% (w/w) of carbon quantum dots was conjugated
on the PDA surface, it still increased the photothermal efficiency
by 30%. Moreover, PDA-PEI@N,S-CQDs could also be used as the drug
carrier for loading 60% (w/w) of the DOX and achieved stimuli-responsive
drug release under lysosomal pH (pH 5.0) and 808 nm laser illumination.
For in vitro therapeutic experiment, PDA-PEI@N,S-CQDs
showed the remarkable therapeutic performance under 808 nm laser irradiation
for killing 90% of cancer cells compared with 50% by pure PDA nanoparticles,
and the efficacy was even higher after loading DOX owing to the synergistic
effect by photothermal therapy and chemotherapy. This intelligent
and effective therapeutic nanosystem based on PDA-PEI@N,S-CQDs showed
enhanced photothermal behavior after chelating carbon dots and promoted
the future development of a nanoplatform for stimuli-responsive photothermal/chemo
therapy.