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Title
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Methods to functionalize gold nanoparticles with tandem-phosphorothioate DNA: role of physicochemical properties of the phosphorothioate backbone in DNA adsorption to gold nanoparticles
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Type
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JournalPaper
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Keywords
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Spheruical Nucleic Acids, Gold Nanoparticle, Freeze-thaw method, Salt-aging method, Low pH method
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Abstract
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Perception of the differences in the physicochemical properties of phosphorothioate DNA (PS-DNA) and phosphodiester DNA (PO-DNA) greatly aids in understanding the AuNP-DNA binding process. Replacing one non-bridging oxygen atom of the anionic phosphodiester backbone with a sulfur atom leads to a major change in the DNA adsorption mechanism of AuNPs. In this work, we investigated and compared salt-aging, low pH-assisted, and freeze–thaw methods for conjugating phosphorothioate- modified oligonucleotides to AuNPs. The results obtained clearly demonstrate that only the pH-assisted method can successfully bind tandem phosphorothioate DNA to gold nanoparticles and sufficiently maintain the colloidal stability of AuNPs. When a phosphate group is converted to a phosphorothioate group, the negative charge of the phosphate group is located on the sulfur atom. Due to the soft nature of sulfur (a very weak H-bond acceptor), the negative charge on the sulfur atom cannot be shielded even with the gradual addition of salt to increase the ionic strength, so, the pH-assisted based method is the best for the functionalization of AuNPs with tandem-PS DNA
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Researchers
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abbas karami (First Researcher), Masoumeh Hasani Mousavi (Second Researcher)
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