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Enhanced photodynamic therapy efficacy by encapsulation of photosensitizes in tyrosine-derived nanospheres

机译：通过封装酪氨酸衍生的纳米球中的光敏剂增强光动力疗法的功效

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Introduction: Photodynamic Therapy (PDT) uses photo-active drugs, which are also called photosensitizer (PS). PS produces reactive oxygen species (ROS) that are responsible to cause cell death. Although many literature data shows convincing results, clinical trials have shown limited therapeutic efficiency due to the low solubility of PS in aqueous media limiting PDT efficacy, deactivation reactions, and poor cellular uptake. Nanocarriers have been successfully used to enhance the therapeutic efficacy of PS by improving PS availability, protecting PS from deactivation reactions and increasing PS uptake. In here we present results of porphyrin encapsulation in tyrosine-derived nanospheres (TyroSpheres) demonstrating intracellular deliver of the PS and improved photo-toxicity to Hela cells compared to free PS. Materials and Methods: Photosensitizers were encapsulated into TyroSpheres as described. The hydrodynamic diameter and polydispersity of the nanospheres was obtained by dynamic light scattering (DLS). Binding efficiency and loading were calculated as in referenced. The amount of PS-TyroSpheres uptaken into HeLa cells was evaluated by absorbance spectrum of PS. Phototoxicity was determined by MTT method. The release of PS from the polymer inside HeLa cells was measured as described. Results and Discussion: Both porphyrins as shown in Figure 1 were encapsulated into TyroSpheres with ～65-70% binding efficiency, while loading values were around 0.5% (w/w). Size distributions and polydispersity index were around 60 nm and 0.2, respectively. Encapsulation of PS within the polymeric micelle results in nanospheres with zeta potential of approximately zero. The uptake of PS-TyroSpheres in HeLa cells was lower than that of free PS (Figure 2A), and both PS were released in the intracellular environment, as suggested by the different intracellular localizations observed for the labelled-polymer and PS (Figure 2C). None of PS showed cytotoxicity in the dark under conditions used, and both showed phototoxicity that increased with PS concentration (Figure 2B). Note that IC_(50) values of PS-TyroSpheres are approximately a third compared with the free PS. Also, IC_(50) values were not the same to TPPS2a-TyroSpheres and CisDiMPyP-TyroSpheres, in agreement with the release of PS from the TyroSpheres in the intracellular environment. The reasons for the better efficiency of PS-tyroshphere compared with the free PS are under investigation. Conclusion: TyroSpheres seems to be a very efficient nanocarrier to deliver PDT PS in the intracellular environment.
机译：简介：光动力疗法（PDT）使用光敏药物，也称为光敏剂（PS）。 PS会产生导致细胞死亡的活性氧（ROS）。尽管许多文献数据显示出令人信服的结果，但是由于PS在水介质中的溶解度低，限制了PDT的功效，失活反应和不良的细胞吸收，临床试验显示出有限的治疗效果。纳米载体已通过改善PS的利用率，保护PS免受失活反应和增加PS的吸收而成功地用于增强PS的治疗功效。在这里，我们介绍了在酪氨酸衍生的纳米球（TyroSpheres）中卟啉封装的结果，证明了PS的胞内递送和与游离PS相比对Hela细胞的光毒性有所改善。材料和方法：如前所述，将光敏剂封装到TyroSpheres中。纳米球的流体动力学直径和多分散性是通过动态光散射（DLS）获得的。结合效率和负载按参考方法计算。通过PS的吸收光谱评估摄取到HeLa细胞中的PS-TyroSpheres的量。通过MTT法测定光毒性。如所述测量PS从HeLa细胞内部的聚合物中的释放。结果与讨论：如图1所示，两种卟啉均以约65-70％的结合效率封装在TyroSpheres中，而负载量约为0.5％（w / w）。尺寸分布和多分散指数分别为约60nm和0.2。 PS在聚合物胶束中的封装会导致纳米球的Zeta电位约为零。 HeLa细胞中PS-TyroSpheres的吸收低于游离PS（图2A），并且两种PS均在细胞内环境中释放，这是由标记聚合物和PS观察到的不同细胞内定位所暗示的（图2C） 。在使用条件下，PS在黑暗中均未显示出细胞毒性，并且均显示出随PS浓度增加的光毒性（图2B）。请注意，与免费PS相比，PS-TyroSpheres的IC_（50）值约为三分之一。同样，IC_（50）值与TPPS2a-TyroSpheres和CisDiMPyP-TyroSpheres不同，这与细胞内环境中TyroSpheres释放PS一致。与免费的PS相比，PS酪氨酸的效率更高的原因正在研究中。结论：TyroSpheres似乎是在细胞内环境中传递PDT PS的非常有效的纳米载体。

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