Poly-tannic acid coated paclitaxel nanocrystals for combinational photothermal-chemotherapy

Combinational photothermal-chemotherapy offers great advantages for the treatment of cancer. To achieve this goal, the poly-tannic acid (pTA) coated paclitaxel nanocrystals (PNC) were prepared, which was denoted as PNC-pTA. Herein, paclitaxel (PTX) was prepared as nanocrystals acting as chemo-agent for chemotherapy. And the tannic acid formed a pTA layer coated on PNC in the presence of Fe³⁺ serving as a potential agent for photothermal therapy (PTT). PNC-pTA was around 470 nm in rod shape and the pTA content was determined to be 11.50 ± 0.48 wt% by mass ratio. pTA exhibited photothermal effect upon laser irradiation of 808 nm, and this effect could be strengthened with the increased amount of Fe³⁺ in pTA. Moreover, pTA showed excellent photostability under repeated laser irradiation. And with the aid of pTA, the cellular uptake of PNC-pTA was greatly enhanced for different cancerous cell lines. PNC-pTA plus laser irradiation showed much stronger cytotoxicity against the 4T1 cell line compared with that without laser irradiation. And the result of animal experiments showed that PNC-pTA exhibited mild photothermal effect in vivo and the strongest tumor inhibition effect upon laser irradiation compared with single photothermal therapy or chemotherapy. These results confirmed the combinational chemo-photothermal effect of PNC-pTA. Our study provided a versatile platform to achieve combined photothermal-chemotherapy with enhanced therapeutic efficacy.