Comparison on the interaction of Al3+/nano-Al13 with calf thymus DNA /salmon sperm DNA

• Al3+ led to hypochromic effect and nano-Al13 caused hyperchromic effect.
• DNA combined with Al3+ on phosphate group but with nano-Al13 on double-helix.
• FTIR and Raman spectra showed different binding sites of Al3+ and nano-Al13 to DNA.

The conformation change, binding mode and binding site between Al3+/nano-Al13 and calf thymus DNA/salmon sperm DNA were investigated by UV–vis absorption, FTIR spectra, Raman spectroscopy and CD spectra, as well as melting curves measurement. The UV–vis spectra and circular dichroism spectra results suggested that the phosphate group structure was changed when Al3+ interacted with DNA, while the double-helix was distorted when nano-Al13 interacted with DNA. The FTIR and Raman spectroscopy revealed that the binding sites were Al3+ … PO2, Al3+ … N7/guanine PO2 … Al13 … N7–C8/guanine with calf thymus DNA, and Al3+ … N3–O2/cytosine, Al3+ … N7–C8/guanine, PO2 … Al13 … N7–C8/guanine, PO2 … Al13 … N1/adenine with salmon sperm DNA, respectively. The electrostatic binding was existed between Al3+ and DNA, and the electrostatic binding and complexing were found between nano-Al13 and DNA.

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