The purpose of this study was to develop a nanocarrier system for codelivery of paclitaxel (PTX) and piperlongumine (PL) and investigate the therapeutic potential of improving efficacy and reducing toxicity. PTX and PL were formulated into poly lactic-co-glycolic acid and D-α-tocopheryl polyethylene glycol succinate via organic solvent evaporation method. The average diameter was 117.1 ± 1.9 nm , and the zeta potential was −43.25 ± 2.76 mV. PL facilitated the cellular uptake of PTX, and the increased cytotoxicity was similarly displayed. The formulation with the PTX/PL concentration ratio at 1:200 showed the best antitumor activity , the IC 50 of PTX were 5.10 ± 0.08 nM in HepG2 cells, and 3.79 ± 1.01 nM in Michigan Cancer Foundation–7 cells. Correspondingly, the combination index was 0.79 and 0.76. Furthermore, intracellular uptake of PTX toward HepG2 cells in coencapsulated nanoparticles was significantly more than free solution. In addition, the antitumor effect of PTX/PL-PTNPs in the HepG2 xenograft tumor model suggested that the nanoparticles showed a higher antitumor efficacy with reduced toxicity to other tissues compared with free PTX. In summary, the results indicated that PTX/PL-PTNPs processed well characteristics and enhanced its therapeutic efficacy; thus, this delivery system could be clinically effective for treatment of cancers.
Recently, nanomaterials with multiple functions, such as drug carrier, magnetic resonance imaging (MRI) and optical imaging, and photothermal therapy, have become more and more popular in cancer research. In this work, a novel redox-sensitive system constructed from hyaluronic acid (HA), single-walled carbon nanotubes (SWCNTs), doxorubicin (DOX), and gadolinium (Gd) was successfully developed. Herein, HA-modified SWCNTs (SWCNTs-HA) was first synthesized, and then DOX was conjugated with HA by disulfide bond (SWCNTs-HA-ss-DOX). Finally, MRI contrast agents, Gd3+-ion loading occurred through the sidewall defects of SWCNTs, whose cytotoxicity could be sequestered within the SWCNTs. In vitro release of DOX showed that this system accomplished much faster drug release under reducing condition. Confocal microscopy analysis confirmed that Gd/SWCNTs-HA-ss-DOX were capable of simultaneously delivering DOX and SWCNTs into Michigan Cancer Foundation-7 cells via HA receptor-mediated endocytosis followed by rapid transport of cargoes into the cytosol. Enhanced cytotoxicity of Gd/SWCNTs-HA-ss-DOX further proved that the sensitive system was more potent for intracellular drug delivery as compared with the insensitive control. Meanwhile, tumor cell killing potency was improved when Gd/SWCNTs-HA-ss-DOX were combined with near-infrared irradiation, with IC50 of 0.61 µg/mL at 48 hours. In vivo investigation demonstrated that Gd/SWCNTs-HA-ss-DOX could effectively accumulate in tumor sites and possessed the greatest synergistic antitumor efficacy, especially under the 808 nm laser irradiation. More importantly, this system could be used as a contrast agent for MRI to identify the location and extent of tumor tissues. These results suggested that Gd/SWCNTs-HA-ss-DOX might be a promising system for targeting chemo-photothermal therapy and MRI diagnosis in future clinical anticancer applications.