Sequence-selective binding of oligonucleotides to superparamagnetic cobalt ferrite nanoparticles: a new way to fabricate functional nanoconjugates

Abstract

The interaction between homo-oligonucleotides and unmodified superparamagnetic cobalt ferrite nanoparticles has been investigated. It has been shown that the binding efficiency depends both on the nucleotide sequence and the chemical composition of the medium. According to the data obtained on the binding suppression of all oligonucleotides, apart from oligo(dG), with the surface in the presence of phosphate anions, an approach to magnetic nanoparticle-oligonucleotide nanoconjugate formation using dG₁₈T₂₅ has been implemented. In the obtained nanoconjugate, nanoparticle binding is realized due to the dG-region, whereas the thymine-containing region remains vacant. According to TEM data, the average nanoconjugate diameter is 6.3 nm; it possesses superparamagnetic properties, and its saturation magnetization is 15 emu g⁻¹. The nanoconjugate has been investigated by FTIR-spectroscopy and XRD-analysis. The hydrodynamic diameter and zeta potential of the nanoconjugate in suspension have been determined. Using fluorescently labelled oligonucleotides, it has been shown that the present nanoconjugate is able to hybridize with oligonucleotides containing a dA sequence at the 3′-end and a variable region at the 5′-end. The conjugate can be isolated from the solution and used for hybridization with the oligonucleotide complementary to the sequences at the 5′-end.