Experimental Approach Using Covalently Attached Fluorophore for Quantification of Oligonucleotide Immobilization on Gold Nanoparticles

In order to control the process of oligonucleotide immobilization on the surface of citrate-stabilized gold nanoparticles, an experimental approach for evaluation of the amount of immobilized oligonucleotides was proposed. This approach is based on using thiolated oligonucleotides with covalently attached fluorophore Cy3 and on comparison of the oligonucleotides concentration before and after immobilization procedure (initial concentration and concentration of unbound oligonucleotides). Their difference gives an unambiguous amount of immobilized oligonucleotides. Application of the proposed experimental approach showed that the efficiency of oligonucleotide immobilization on the surface of gold nanoparticles is strongly dependent on the ionic strength of the medium, oligonucleotide concentration and the temperature of immobilization. The proposed experimental approach for determination of the level of oligonucleotide immobilization on the surface of gold nanoparticles is simple, fast and does not use any toxic chemicals.

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