DNA Aptamer Folding on Gold Nanoparticles: From Colloid Chemistry to Biosensors

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• 作者：Weian Zhao ; William Chiuman ; Jeffrey C. F. Lam ; Simon A. McManus ; Wei Chen ; Yuguo Cui ; Robert Pelton ; Michael A. Brook ; Yingfu Li
• 刊名：Journal of the American Chemical Society
• 出版年：2008
• 出版时间：March 19, 2008
• 年：2008
• 卷：130
• 期：11
• 页码：3610 - 3618
• 全文大小：323K
• 年卷期：v.130,no.11(March 19, 2008)
• ISSN：1520-5126

文摘

We have investigated the effect of the folding of DNA aptamers on the colloidal stability of goldnanoparticles (AuNPs) to which an aptamer is tethered. On the basis of the studies of two different aptamers(adenosine aptamer and K⁺ aptamer), we discovered a unique colloidal stabilization effect associated withaptamer folding: AuNPs to which folded aptamer structures are attached are more stable toward salt-induced aggregation than those tethered to unfolded aptamers. This colloidal stabilization effect is moresignificant when a DNA spacer was incorporated between AuNP and the aptamer or when lower aptamersurface graft densities were used. The conformation that aptamers adopt on the surface appears to be akey factor that determines the relative stability of different AuNPs. Dynamic light scattering experimentsrevealed that the sizes of AuNPs modified with folded aptamers were larger than those of AuNPs modifiedwith unfolded (but largely collapsed) aptamers in salt solution. From both the electrostatic and stericstabilization points of view, the folded aptamers that are more extended from the surface have a higherstabilization effect on AuNP than the unfolded aptamers. On the basis of this unique phenomenon,colorimetric biosensors have been developed for the detection of adenosine, K⁺, adenosine deaminase,and its inhibitors. Moreover, distinct AuNP aggregation and redispersion stages can be readily operatedby controlling aptamer folding and unfolding states with the addition of adenosine and adenosine deaminase.