Interaction between poly(amidoamine) dendrimers and DNA studied by spectroscopic methods

The interaction between amino-terminated, and ethylenediamine core poly(amidoamine) (PAMAM) den-drimers and herring sperm DNA was investigated by various spectroscopic methods including UV spectroscopy, fluores-cence spectroscopy, microscopic FTIR- and circular dichro-ism (CD-) spectroscopy. Ethidium bromide (EB) is used as a nucleic acid probe for this study. Experimental results show that PAMAM dendrimers can form stable complexes with DNA and the dendrimers bind to DNA sufficiently strong which cannot be displaced by EB, and we also found that the formation of the complexes can cause the conformation change of the DNA secondary structure. According to the Scatchard analysis, the association constant of PAMAM to DNA is calculated to be 2.53 × 104 mol/L?1.