Controllable microstructure of Au nanoparticle-DNA oligonucleotide conjugates

The Au nanoparticle (AuNPs) and DNA oligonucleotide conjugates will have complicated microstructures because one AuNP can be conjugated to more than one single-stranded DNA (ssDNA) on its surface. In this paper, the AuNPs-DNA conjugates with controllable microstructure were prepared on SiO2 microsphere carriers. The reactions between AuNPs with ssDNA on SiO2 carriers were sterically restricted because only out part surface of AuNPs on carriers could react with ssDNA. When two kinds of AuNPs with different diameters, 15 nm and 50 nm, were conjugated with two complementary ssDNA, cleaved from carries and hybridized each other, the AuNPs-DNA conjugates were prepared. The TEM results indicated that when the particle size of AuNPs was about 50 nm, 1 AuNP could be conjugated to 2 ssDNA on its surface, while 1 AuNP (15 nm) particle was only conjugated to 1 ssDNA on its surface.