Weronika Kotkowiak, Michał Kotkowiak, Anna Pasternak, Ryszard Kierzek and Alina Dudkowiak
Institute of Bioorganic Chemistry, Polish Academy of Science 61-074, Z., Noskowskiego 12/14 Poznan,
Photodynamic therapy (PDT) and photodynamic diagnosis (PDD) are important types of clinically approved therapeutic tools for cancer treatment. PDT is based on light excitation of a photosensitizer to produce highly reactive singlet oxygen (1O2) and free radicals. Recently, a new type of twodimensional molecular beacons i.e. RNA-activated cancer therapeutics have attracted more attention [1, 2].
Spherical nucleic acids (SNAs), firstly introduced by Mirkin in 1996 , are revolutionizing drug delivery, gene therapy and diagnostics [4, 5]. SNAs are defined as a structures, which are arranged of densely packed, highly oriented nucleic acids in a spherical geometry. In comparison to linear nucleic acids, SNAs are characterized by narrow melting transition, higher nuclease resistance and twice time higher binding affinity, furthermore transfection into the cells is not required .
In this work for the first of time we have presented application of SNAs for PDT and/or PDD. Furthermore, the influence of multiwavelength excitation of photosensitizers (pheophorbide a and hematoporphyrin) on the interactions with pegylated gold nanoparticle (Au-NPs) and the photophysical parameters of the dyes are studied. Synthetized Au-NPs were used for SNAs molecular beacons designing. We have observed different behavior of the mixtures on excitation with the wavelengths. Moreover, for certain concentrations of Au-NPs and for certain excitation wavelengths, an increase in singlet oxygen generation was observed .
Keywords: Chlorophylls, spherical nucleic acids, gold nanoparticles, photophysics, photodynamic therapy and diagnosis.
This work was supported by the National Science Center in Poland grant number 2013/11/N/NZ7/00738.
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