engleski

Surface-enhanced Raman study of the interactions between pyrene derivative of polyamine and double- stranded polynucleotides

Antitumor drugs, which bind as ligands to the double helix of deoxyribonucleic acid (DNA), are often structurally related to polyamines [1]. Since tumor cells use biogenic polyamines in much larger quantities than healthy cells, polyamines seem to be good candidates to synthesize new drugs or improve the activity of existing ones [2]. In this work surface-enhanced Raman scattering (SERS) was used to study interactions between a new pyrene derivative of tripodal polyamine and double-stranded polynucleotides: poly dA – poly dT, poly dG – poly dC, poly rA – poly rU and calf thymus DNA. Citrate-reduced silver colloid was used as the metal substrate. Mixtures of polyamine with polynucleotides were prepared in [polyamine]/[polynucleotide] molar ratios of 1/1, 1/5 and 1/10, while concentration of polyamine was 5×10–6 mol/dm3. Polynucleotides bands were missing from the obtained SERS spectra of all prepared polyamine/DNA mixtures, while weak bands, originating from polyamine molecules, appeared in the SERS spectra of all complexes, even at large excess of polynucleotides. Pyrene rings probably intercalated between the base pairs of DNA analoges, while unbonded part of the molecules remained close to the metal surface. SERS spectra of polyamine/poly rA – poly rU mixtures showed negligible changes in intensity of polyamine bands, if compared to the SERS spectrum of free polyamine, probably due to lack of interactions between polyamine molecules and RNA.

polyamine ; pyrene ; SERS ; polynucleotides

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