Abstract
DNA nanotechnology offers the possibility to rationally design structures with emergent properties by precisely controlling their geometry and functionality. Here, we demonstrate a DNA-based plasmonic metamolecule that is capable of sensing human thrombin proteins. The chiral reconfigurability of a DNA origami structure carrying two gold nanorods was used to provide optical read-out of thrombin binding through changes in the displayed plasmonic circular dichroism. In our experiments, each arm of the structure was modified with one of two different thrombin-binding aptamers—thrombin-binding aptamer (TBA) and HD22—in such a way that a thrombin molecule could be sandwiched by the aptamers to lock the metamolecule in a state of defined chirality. Our structure exhibited a Kd of 1.4 nM, which was an order of magnitude lower than those of the individual aptamers. The increased sensitivity arose from the avidity gained by the cooperative binding of the two aptamers, which was also reflected by a Hill coefficient of 1.3 ± 0.3. As we further exploited the strong plasmonic circular dichroism (CD) signals of the metamolecule, our method allowed one-step, high sensitivity optical detection of human thrombin proteins in solution.
Highlights
Since its introduction in 1990, single-stranded DNA and RNA aptamers have become important targets of diagnostic and clinical studies because of their cost effectiveness, stability, affinity, and small size [1,2,3,4,5,6,7,8]
The 3D plasmonic metamolecules were designed as in the previous paper [25], with the only difference being that the staple strands “arm a” were replaced with “arm a thrombin-binding aptamer (TBA)”, “arm b (57 nt)” with “arm b2 HD22” and “arm b (86 nt)” with “arm b blank” (Table 1)
We demonstrated that our plasmonic metamolecule reliably detected human alpha thrombin in solution at concentrations of 100 pM and above
Summary
Since its introduction in 1990, single-stranded DNA and RNA aptamers have become important targets of diagnostic and clinical studies because of their cost effectiveness, stability, affinity, and small size [1,2,3,4,5,6,7,8]. By using specially designed nanostructures, the detection limit has been pushed towards the single-molecule level. Another method to increase overall sensitivity relies on gaining avidity by using two aptamers that bind to one target molecule but on different epitopes. Connecting two thrombin-binding aptamers with a single-stranded DNA linker increased binding affinity up to 10-fold, when compared to individual aptamers [20]. We used the DNA origami technique [21,22,23,24,25,26,27,28,29,30], which enables us to build dynamic
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
