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Effective Photo-Enhancement of Cellular Activity of Fluorophore-Octaarginine Antisense PNA Conjugates Correlates With Singlet Oxygen Formation, Endosomal Escape and Chromophore Lipophilicity

Reza Yarani, Takehiko Shiraishi, Peter E Nielsen

Sci Rep. 2018 Jan 12;8(1):638.

PMID: 29330463

Abstract:

Photochemical internalization (PCI) is a cellular drug delivery method based on the generation of light-induced reactive oxygen species (ROS) causing damage to the endosomal membrane and thereby resulting in drug release to the cytoplasm. In our study a series of antisense fluorophore octaarginine peptide nucleic acid (PNA) conjugates were investigated in terms of PCI assisted cellular activity. It is found that tetramethylrhodamine and Alexa Fluor 555 conjugated octaarginine PNA upon irradiation exhibit more than ten-fold increase in antisense activity in the HeLa pLuc705 luciferase splice correction assay. An analogous fluorescein conjugate did not show any significant enhancement due to photobleaching, and neither did an Alexa Fluor 488 conjugate. Using fluorescence microscopy a correlation between endosomal escape and antisense activity was demonstrated, and in parallel a correlation to localized formation of ROS assigned primarily to singlet oxygen was also observed. The results show that tetramethylrhodamine (and to lesser extent Alexa Fluor 555) conjugated octaarginine PNAs are as effectively delivered to the cytosol compartment by PCI as by chloroquine assisted delivery and also indicate that efficient photodynamic endosomal escape is strongly dependent on the quantum yield for photochemical singlet oxygen formation, photostability as well as the lipophilicity of the chromophore.

Chemicals Related in the Paper:

Catalog Number Product Name Structure CAS Number Price
IAR424664 Ovalbumin-Atto 488 conjugate Ovalbumin-Atto 488 conjugate Price
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