Dual‐Stage‐Light‐Guided Tumor Inhibition by Mitochondria‐Targeted Photodynamic Therapy

In this paper, a self‐delivery system PpIX‐PEG‐(KLAKLAK)₂ (designated as PPK) is fabricated to realize mitochondria‐targeted photodynamic tumor therapy. It is found that the PPK self‐delivery system exhibited high drug loading efficacy as well as novel capacity in generation of intracellular reactive oxygen species (ROS). This study also indicated that the photochemical internalization effect of the photosensitizer protoporphyrin IX (PpIX) under a short time light irradiation improved the cellular internalization of PPK. On the contrary, PPK could target to the subcellular organelle mitochondria due to the presence of proapoptosis (KLAKLAK)₂ peptide. Importantly, the in situ generation of ROS in mitochondria enhanced the photodynamic therapy efficacy under another long time irradiation, leading to significant cell death with decreased mitochondrial membrane potential. Besides, relative high tumor accumulation, minimal systemic cytotoxicity and efficacious long‐term tumor inhibition in vivo are also confirmed by using a murine model. All these results demonstrated the self‐delivery system PPK with a dual‐stage light irradiation strategy is a promising nanoplatform for tumor treatment.     

A Tumor Targeted Chimeric Peptide for Synergistic Endosomal Escape and Therapy by Dual‐Stage Light Manipulation

In this study, a pH sensitive chimeric peptide is developed to codeliver a photosensitizer, protoporphyrin IX (PpIX), and plasmid DNA simultaneously. In the presence of matrix metalloproteinase‐2 (MMP‐2), the chimeric peptide undergoes the process of hydrolysis of PLGVR peptide sequence, exfoliation of PEG, and increase of positive charges. As a result, the chimeric peptide can be preferentially uptaken by MMP‐2 rich tumor cells. To realize synergistic effect of drug and gene delivery, a dual‐stage light irradiation strategy is developed, i.e., the short time light irradiation can efficiently enhance the endosomal escape of the chimeric peptide/PpIX/DNA complexes by the formation the reactive oxygen species (ROS), resulting in synergistic endosomal escape and improved DNA expression. In addition, due to the screened phototoxicity of PpIX, short time light irradiation does not lead to detectable changes in the cell viability. After the gene transfection, the screened phototoxicity of PpIX is subsequently stimulated by long time irradiation to achieve high synergistic efficacy of photodynamic and gene therapies. Both in vitro and in vivo studies confirm the chimeric peptide‐based nanocarrier with a good synergistic effect is a promising nanoplatform for tumor treatments.