Instruments
Transmission Electron Microscope (TEM)
TEM uses electron shots to project onto a very thin sample, in which the electrons collide with atoms. After collision, the trajectory of the electrons changes, resulting in solid angle scattering. With the scattering of different angles, different brightness could be observed, which creates the images we see under TEM.
Imaging- forming consequence
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Absorption image:
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For samples of high mass and density, the main phase-forming effect is scattering. The thicker the mass, the larger the scattering angle of electrons. Thus, there are fewer electrons passing through the mass, resulting in a dark image.
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Diffraction image:
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After the electron beam is diffracted by the sample, the amplitude of the diffraction wave at different positions corresponds to different diffraction ability of each part of the sample. The amplitude distribution of the diffracted waves is not uniform, thus constructing the images.
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Phase image:
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When the sample is as thin as 100Å or less, electrons can pass through the sample. The imaging comes from the phase change.
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Why choose TEM?
＊ Most powerful magnification compared to other micro spectroscopy.
＊ Provide high-quality and detailed information on molecule structure.
＊ Clear images on surface features, shape, size and structure.
＊ Easy to operate with proper training
To conclude, TEM is the best choice for us to verify the structure of our works.
Sample Observation
After the copper grid is properly loaded with our sample, we use Hitachi H-6750 for the sample observation.
Agarose Electrophoresis
Electrophoresis refers to the phenomenon that charged molecules move in a fluid under the action of a uniform electric field. DNA is negatively-charged, so we use electrophoresis to perform the separation on PCR products.
Going through lots of trial and error, we have found the most suitable concentration of agarose for each component combination tested. This way we can make sure that the result of agarose electrophoresis is credible.
Most importantly, agarose electrophoresis allows us to examine the result of PCR and make preliminary deductions on our DNA origami combinations.
PCR Machine (Polymerase Chain Reaction)
Normally, PCR is used to amply specific DNA samples. However, in our experiment, we utilize its consecutive change in temperature to carry out various combinations of our DNA origami components.
Steps
The procedure for the DNA origami combination using PCR apparatus is as follows:
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Heat up to 80°C and then incubate for 10 mins.
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Cool down from 80°C to 61°C at the rate 4 min / °C.
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Further cool down from 60°C to 25°C at 20 min / °C.
The whole procedure lasts approximately 13 hours and it is conducted inside Bio-rad T100 PCR apparatus.
Ultrasonic Oscillator
Used to suspend and disentangle the DNA staples and the later-added DNA origami components with the ultrasonic oscillation created by machine.
Instruments Gallery
