Background
Nowadays, targeted drug-delivery, biosensing, and nanodevices has been increasingly gaining popularity. Among these fields, the design of nanodevices has been the talk of the town in medicine, owing to its ability to reach deep parts of the body and carry out specific tasks. Though promising, there are still two main problems waiting to be solved. One is biocompatibility, the other is the precise manipulation of nanodevices.
Introduction to DNA Origami
Fortunately, with the advent of DNA Origami technique, we can now kill two birds with one stone. But what is DNA Origami actually? DNA is the language of life, which utilizes base pairs to preserve essential messages. “Origami” is a Japanese word that means the folding of a plain sheet into an arbitrary form having a specific dimensions. Recently, scientists have gotten the best of both worlds via a fascinating technique called DNA Origami. Using the simple pairing nature of four bases as the folding force, we can easily design the sequence needed to form the specific 3D origami structure in nanoscale. This most recent technique has immense potential in a wide range of fields. Since DNA is biocompatible, it is an ideal material to make nanodevices sent into human bodies. Additionally, the simple pairing nature of DNA's four bases makes the movements of DNA nanodevices relatively easy to control.
Motivation
Over the years, scientists and the former Biomod contestants have been striving to bring basic forms of mechanical movements down to the nanoscale. We have seen linear and rotational motions being successfully carried out. However, our team wants to take simple mechanical movements up a notch. In the past, it is relatively rare to see a device that can change its outer surface property at will, or to rotate at a fixed position. Therefore, our idea is born.
Idea
Our inspiration comes from our childhood memories — paper fortune teller. It is an origami akin to the shape of a flower. Normally, we draw various colors or numbers on the outside of the origami, while concealing the "fortune" on the inside. The hiding function of the paper fortune teller inspires us to design a nano-device capable of changing its surface identity, revealing different sides. That's when we decided to call it "NANO FACE-OFF".
Figure 1: Paper fortune teller (image source)
In the slideshow below, we can see our three-component DNA origami structure. The bottom piece, being conveniently called the "base”, serves as a platform with three sets of “pillars” to precisely control the rotation of two upper pieces, called the "lids”. Due to toehold-mediated strand displacement, the specifically designed DNA sequences can act either as linker or anti-linker to change the structure of our nanodevice. For more detail on structural information and mechanism, please check out our design page.
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To change its face, our structure can switch “identity” by turning out the inner surface of the lid, while hiding the original identity on the outside when supplied with specific DNA fragments. The so-called “identity” can be determined via chemical modifications on each surface with certain ligands of interest.
Project Goals
There is a trade-off between setting realistic goals to be achieved within the timeframe of BIOMOD and setting goals that are scientifically thrilling and significant. Though the development of our "NANO FACE-OFF" may be explored in various directions, we decided to choose primary goals that enable us to test out the core concept and the feasibility of our mechanisms.
There are three goals that we hope to achieve as a proof of concept for our mechanism:
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To constuct 3 individual components: the base, and the two lids.
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To successfully assemble the components together.
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To check if our "face-changing" mechanism can work.
Prospect
This structure holds the potential for several innovative future applications. This device can serve as a platform for us to coat different molecules on each surface, and when it encounter certain signals (such as ssDNA), it can change its surface property. Furthermore, the changing of distance between surfaces can also induce desired reaction if we modify the edges of each surface with proper reagents.
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Using the two essential ideas, rotation and hiding function, there are countless opportunities for us to discover.