金纳米粒子与单链DNA的相互作用

Interaction Between Gold Nanoparticles and ssDNA

研究了金纳米粒子与单链DNA在不同pH值时的相互作用以及金纳米粒子与不同碱基序列单链DNA的相互作用.结果表明,在pH为12.6的强碱性条件下,单链DNA能使金纳米粒子稳定分散在溶液中;在pH为1.4的强酸性条件下,单链DNA能保护金纳米粒子不发生融合,而只发生团聚,且团聚现象具有可逆性.不同寡核苷酸对金纳米粒子的亲和力按poly dA>poly dC>poly dT的顺序依次减弱.单链DNA对纳米金的保护作用强度与单链DNA的长度成正比.

The interaction between unmodified gold nanoparticles and single-stranded DNA （ssDNA） was studied at different pH value. And the sequence-dependent stability of ssDNA-GNPs complex was investigated. GNPs precipitated from red colloid solution in the form of aggregation after alkalization with NaOH or dissolve after acidification with HCl. Both processes were irreversible. If the same particles were incubated with ssDNA, ssDNA-GNPs complex were stable against NaOH-induced aggregation at pH = 12.6, and aggregated at pH = 1.4, while redispersed at pH = 12.6. It was concluded that unmodified GNPs could be coated by unmodified ssDNA, which protected GNPs dispersing in solution at pH = 12.6, and prevented GNPs from dissolving at pH = 1.4, as measured by TEM and UV-Vis absorption spectrum. The bindig affinities of oligonucle- otides to GNPs were different in the order of poly dA 〉 poly dC 〉 poly dT. Moreover, longer ssDNA had stronger protective effect to gold nanoparticles. HCl-induced GNPs aggregation could be an effective method to identify the diversity of deoxyribonueleotides in ssDNA sequences.