ICG-PDA-TPZ Nanoparticles For Enhancing Antitumor Efficiency By Combined Phototherapy And Chemotherapy

Cancer incidence has been increasing worldwide in recent years,and the therapeutic efficacy can be efficiently enhanced by combination therapies.Hence,we developed acid-and photothermal-sensitive CaCO3-polydopamine(PDA)nanoparticles,with load of indocyanine green(ICG,a near-infrared photosensitizer)and tirapazamine(TPZ,a hypoxia-activated prodrug).The NPs were then modified with D-a-Tocopheryl polyethylene glycol 1000 succinate(TPGS)and c(RGDfK)peptide to fabricate the multifunctional nano-drug delivery system(NDDS)with long-circulating property and integrin αvβ3 receptor targeting ability.Physicochemical properties,antitumor effects and safety of the NPs were assessed to provide theoretical and experimental bases for combined antitumor photodynamic,photothermal and chemo-therapy.The TPZ-loaded CaCO3-PDA nanoparticles(PDA-TPZ NPs)were firstly prepared.Fourier transform infrared spectra and electron spin resonance spectra characterization verified the successful synthesis of PDA.ICG was then loaded onto the PDA NPs by π-π stacking,with modification of amphipathic TPGS and TPGS-RGD after that.The obtained ICG-PDA-TPZ NPs were 178.5± 1.8 nm in diameter and the zeta potential were-23.7±0.3 mV.They showed spherical particles in TEM analysis.Loading efficiency values of the NPs were 5.6%for ICG and 1.1%for TPZ,and TPZ showed acid-sensitive in-vitro release property.Singlet oxygen generation and photothermal effects of the NPs were evaluated in vitro,and the results revealed that both photodynamic and photothermal effects of ICG-PDA NPs were superior than free ICG or PDA NPs.Effective reactive oxygen species(ROS)generation of ICG-PDA NPs was proved in U87MG cells utilizing DCFH-DA.Cellular uptake experiment showed that RGD modification and photothermal effect could significantly increase U87MG cellular uptake of the NPs.MTT assays revealed enhanced tumor cells killing of ICG-PDA-TPZ NPs(IC50=0.15 μg/mL).compared with ICG-PDA NPs and free TPZ(IC50 values were 6.96 and 125.14μg/mL,respectively).Results of cell apoptosis experiment also indicated increased apoptotic efficacy of ICG-PDA-TPZ NPs.Subcutaneous U87MG tumor-bearing mice and orthotopic B16F10 tumor-bearing mice were selected as in-vivo tumor models,to evaluate blood circulation,distribution,antitumor efficacy and safety of the NPs in vivo.The pharmacokinetics experiment,in-vivo distribution experiment and in-vivo photothermal effect evaluation indicated prolonged blood circulation time,better targeting effect and increased tumor temperature of the c(RGDfK)and TPGS-decorated NPs.In-vivo tumor inhibition experiment,bodyweight variation during treatments and histopathological analysis revealed better antitumor efficacy(inhibition rate of tumor growth was-87.3%)and safety of the ICG-PDA-TPZ NPs.Thus,the NPs combined photodynamic,photothermal and chemo-therapy developed in this study can provide a good theoretical basis for the development of NDDS in tumor treatment.