A Fluorescence-Based Method for Determining the Surface Coverage and Hybridization Efficiency of Thiol-Capped Oligonucleotides Bound to Gold Thin Films and Nanoparticle

摘要

Using a fluorescence-based method, we have determined the number of thiol-derivatized single-stranded oligonucleotides bound to gold nanoparticles and their extent of hybridization with complementary oligonucleotides in solution. Oligonucleotide surface coverages of hexanethiol 12-mer oligonucleotides on gold nanoparticles (34 (+-) 1 pmol/cm~2) were significanlty higher than on planar gold thin films (18 (+-)3 pmol/cm~2), while the percentage of hybridizable strands on the gold naoparticles (1.3(+-)0.3 pmol/cm~2, 4%) was lower than for gold thin films (6(+-)2 pmol/cm~2, 33%). A gradual increase in electrolyte concentration over the courseof oligonucleotide deposition significantly increases surface coverage and consequently particle stability. In addition, oligonucleotide spacer seuences improve the hybridization efficiency of oligonucleotide-modified nanoparticles from approx 4 to 44