PNA–Rose Bengal Conjugates as Efficient DNA Photomodulators

Abstract

Selective photoinduced modulation of DNA may provide a powerful therapeutic tool allowing spatial and temporal control of the photochemical reaction. We have explored the photoreactivity of peptide nucleic acid (PNA) conjugates that were conjugated to a highly potent photosensitizer, Rose Bengal (RB). In addition, a short PEGylated peptide (K-PEG8-K) was conjugated to the C-terminus of the PNA to improve its water solubility. A short irradiation (visible light) of PNA conjugates with a synthetic DNA resulted in highly efficient photomodulation of the DNA as evidenced by polyacrylamide gel electrophoresis (PAGE). In addition, a PNA-RB conjugate replacing K-PEG8-K with four l-glutamic acids (E4) was found to be photoinactive. Irradiation of active PNA-RB conjugates with synthetic DNA in D20 augments the photoactivity; supporting the involvement of singlet oxygen. PAGE, HPLC, and MALDI-TOF analyses indicate that PNA-DNA photo-cross-linking is a significant pathway in the observed photoreactivity. Selective photo-cross-linking of such PNA-RB conjugates may be a novel approach to selective photodynamic therapy (sPDT) as such molecules would be sequence-specific, cell-permeable, and photoactivated in the visible region.

Visible-Light-Mediated Modification and Manipulation of Biomacromolecules

“…In 2015, Wang and co-workers incorporated a pentafluoroazobenzene-based click amino acid (F−PSCaa, 360) into calmodulin (CaM), a calcium-binding messenger protein, in E. coli via genetic code expansion (Scheme 104). 623 Following expression of the functionalized protein, F−PSCaa (360) reacted with a strategically placed cysteine residue to generate the azobenzene bridge in situ without any further treatment. The resultant bridge was reversibly switched between its trans and cis isomers using green and blue light, respectively.…”

“…Shemesh and Yavin reported an approach to target cross-linking to specific DNA sequences (Scheme ). Using a 10-mer peptide nucleic acid (PNA) modified with rose bengal ( 44 ) at the N-terminus and a C-terminal PEG 8 -spaced bis­(lysine) unit (K-PEG 8 -K), they observed relatively poor hybridization with a complementary ssDNA sequence. Nevertheless, monitoring the reaction under irradiation with polyacrylamide gel electrophoresis showed that the target ssDNA band was reduced as a new nonmigrating residue accumulated in the wells.…”

Near-infrared photodynamic and photothermal co-therapy based on organic small molecular dyes

“…For example, the photoreactive peptide nucleic acid (PNA) can be used to conjugate the PS Rose Bengal (RB) with PNA–RB, which exhibits sequence specificity, cell permeability, and photoactivation in the visible region. PNA–RB conjugates with synthetic DNA show enhanced photoactivity and support the involvement of 1 O 2 and may provide useful approach for selective PDT [ 102 ]. Moreover, the encapsulation of PSs into PEG is conducive for enhancing phototoxicity.…”

A Photosensitized Singlet Oxygen (1O2) Toolbox for Bio-Organic Applications: Tailoring 1O2 Generation for DNA and Protein Labelling, Targeting and Biosensing

“…Yavin and colleagues proposed an alternative approach to the strategies illustrated above. Taking advantage of the high sensitivity of guanine towards 1 O 2 -mediated photo-oxidation, they synthesized peptide nucleic acids (PNAs) bearing a strong PS (RB) on a complementary G-rich DNA target [ 185 ]. The group illustrated the possibility to selectively induce oxidation of the target strand, with the subsequent formation of ICL products, presumably due to the reaction of 8-oxo-dG with the nucleophilic lysine introduced on the PNA strand (as described above in Section 2.2 ) [ 63 , 186 ].…”

“…An example can be found in the use of synthetic probes complementary to an oligonucleotide target, decorated with a PS. A valuable example is reported by the Yavin group (see above Section 3.2 ), in which PNA probes, decorated with RB, could effectively and selectively target the DNA of choice [ 185 ]. Several methodologies featuring the conjugation of PS to oligonucleotides and analogues were reported in the literature, exploiting the principle of selective recognition to limit ROS generation to the targeted strand, leading to high levels of selectivity.…”