A comparison between mesoporous and nonporous polydopamine as nanoplatforms for synergistic chemo-photothermal therapy

Photothermal therapy (PTT) combined with chemotherapy can break through the limitations of monotherapy and enhance the therapeutic efficacy. Polydopamine (PDA), an organic material with excellent photothermal conversion property and degradability, has broad application prospects in PTT. In this paper, PDA nanoparticles and mesoporous polydopamine (MPDA) nanoparticles were prepared with similar and uniform particle size to compare the photothermal performance, degradability, drug loading efficiency and release behavior. Polyethylene glycol (PEG) was coated on the surfaces of PDA and MPDA to boost their dispersion stability and biocompatibility. In vitro experimental results revealed that the two vehicles had satisfactory photothermal effect, drug storage capacity, and multi-responsive release properties of near-infrared (NIR) light /pH/H2O2/glutathione (GSH) for doxorubicin (DOX), while MPDA-PEG had superior photothermal performance, drug loading efficiency and longer-lasting release due to the mesoporous structure and higher surface area. Degradation experiments showed that MPDA degraded more quickly than PDA. The degradation behaviors of MPDA under different conditions were observed, and the possible degradation process was illustrated. Furthermore, the cell viability tests verified that DOX/MPDA-PEG had more eminent synergistic therapeutic effects in thermo-chemotherapy with a lower combination index (CI) of 0.313 compared with DOX/PDA-PEG (0.497). Therefore, MPDA has a broader application prospect for thermo-chemotherapy.