Y(III) interactions with guanine oligonucleotides covalently attached to aqueous/solid interfaces

Area of Science:

• Biophysical Chemistry
• Nanotechnology
• Materials Science

Background:

• Understanding ion-nucleic acid interactions is crucial for developing novel nanomaterials and therapeutics.
• Previous studies focused on divalent metal ions, leaving interactions with trivalent ions less explored.
• Surface-immobilized oligonucleotides provide a controlled environment to study these interactions.

Purpose of the Study:

• To investigate the binding characteristics of Yttrium (III) ions to surface-bound guanine oligonucleotides (G(20)).
• To quantify the binding affinity and mechanism of Y(III) interaction with G(20).
• To compare Y(III) binding with previously reported divalent metal ion interactions.

Main Methods:

• Eisenthal χ((3)) technique to measure binding thermodynamics.
• Atomic Force Microscopy (AFM) to assess structural changes.
• Surface functionalization with single-stranded guanine 20-mers (G(20)).

Main Results:

• Yttrium (III) binding to G(20) exhibited a free energy of -39.5(8) kJ/mol.
• Yttrium binds significantly stronger to oligonucleotides than previously reported divalent metals.
• Y(III) ion densities ranged from one to three ions per strand, lower than Mg(II).
• AFM revealed no significant decrease in oligonucleotide height upon Y(III) binding.

Conclusions:

• Yttrium (III) ions bind to G(20) via an outer-sphere mechanism, likely involving fully hydrated ions.
• The stronger binding and lower ion density compared to Mg(II) may be due to Y(III)'s larger hydration sphere radius.
• Y(III) binding does not significantly reduce intrastrand Coulombic repulsions, as evidenced by the lack of height decrease.