NEMS are nanometric electromechanical systems. In this case we take as basis the structure of a resonator which are engineered to make a conversión between energy, such as electric, magnetic, or vibrational into mechanical response.

How exactly do NEMS come into play in our project?

Well, by combining an inorganically synthesized nanoparticle, called magnetite and DNA into what we call BioNEMS drill.

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The first part of the synthesis of our magnetite was trying out different methods and characterizing them, to note which method had given us the smallest size nanoparticles. Our first method was synthesis by coprecipitation, of which we prepared nine samples with different concentrations of iron(II) chloride and ammonium hydroxide; from this method we consistently obtained nanoparticles rounding 0.9 to 1nm. Our following method was very similar, but included water in the synthesis: the size of our particles would vary greatly, from 3.89 micrometers to 171 nanometers in size.

After choosing the best method possible, it was time to silanize our magnetite in order for it to be biocompatible with DNA and be able to tie them together. In order for the silanization to take place, we used a solution of TEOS (tetraethoxysilane) dispersed in a medium of water and propanol and dripped this mix slowly onto our magnetite. Just like when we synthesized our particles, we tested different concentrations of TEOS and magnetite, as well as different addition rates in order to observe which combination would give us the smallest possible nanoparticles.

Our results were then characterized by DLS (dynamic light scattering), for which we observed a peak at 39 nm, once coated with TEOS, the peak was moved toward 60 and 80 nm. We also ran our two samples in the IR, comparing the spectra of the pure magnetite and silanized magnetite, we were able to distinguish a peak at 990.2 cm^-1 corresponding to a Si-O bond, confirming the correct silanization of the magnetite.

Having done this, we then prepped our protein by resuspending it in a mix of Tris/acetate and EDTA in order to be able to combine it with our DNA. Then we dispersed our magnetite in anhydric toluene and we added the resuspended protein and we added as well some glutaraldehyde as a coupling agent. We also made some batches without any glutaraldehyde, to compare the comparable strength of their bonds.

We then needed to grow and then extract from E. Coli the DNA we were to use for the rest of our project. We tested two different methods: one of which was the well-known mini prep and the other was very similar but without using an enzyme. Using the DNA we have extracted, we then needed to transform these cells to make competent cells.

These cells we had transformed, we then had to purify, by precipitating in presence of ethanol and centrifugation to eliminate supernatant. We did different dilutions of DNA and combined them with our protein, HU. These as well were divided again in gluteraldehyde and no gluteraldehyde and subsecuently in DNA and not DNA. We did some UV characterization for all samples. We discovered that the solutions with glutaraldehyde had stronger bonds between DNA and HU. We prepared some samples: one with glutaraldehyde and DNA-Hu, another just with glutaraldehyde and DNA, the third one just with DNA-HU and the last one just with DNA and prepared them with nanoparticles and ran them through UV.