Relation of Photochemical Internalization to Heat, pH, and Ca2+ Ions

In this study, we examined the relation of PCI to heat, pH and Ca2+ ions using cell penetrating peptide (CPP) ‐cargo‐photosensitizer (Alexa546 or Alexa633) conjugates. A cell temperature changing experiment demonstrated that heat (thermal mechanism) does not significantly contribute to the photoinduced endosomal escape. Inhibition of V‐ATPase proton pump activity and endosomal pH upregulation indicate d that PCI‐mediated endosomal escape needs endosomal acidification prior to photoirradiation. Imaging of the CPP‐cargo‐photosensitizer and Ca2+ ions during photostimulation showed that intracellular calcium increase is not the cause of the endosomal escape of the complex. The increment is mainly due to Ca2+ influx. These findings show the importance of extra ‐ and intracellular milieu conditions in the PCI mechanism and enrich our understanding of PCI‐related changes in cell.
Source: Photochemistry and Photobiology - Category: Science Authors: Tags: Research Article Source Type: research
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