During our Experiments we used abreviations to simplify the results annotation. MN = Microneedle FD = Flavescence Dorée BN = Bois Noir EC = Endogeneous Control (DNA from grapevines)
DNA Extraction
To test our method of extraction, we used non-infected grapevine leaf.
To detect the product of the extraction, we performed an amplification by PCR. We compared the extraction by microneedles
to a traditional kit-based extraction. The control is synthetic endogeneous control DNA sequence (EC sequence).
We amplified different EC DNA by PCR and ran a gel electrophoresis to analyze the results.
We loaded the gel from left to right as following, the ladder, synthetic EC DNA sequence,
DNA extracted with a microneedle patch, DNA extracted with a standard kit, control with primers but no DNA.
Bands are observed in all the lanes containing DNA, no band is present in the control. This shows that the
microneedle patch successfully extracted DNA from the plant, which was then amplified by PCR.
We used the Nanodrop to analyze the DNA extracted with a microneedle patch (red).
The positive control (green) is EC synthetic DNA sequence and the negative control (blue)
is the elution buffer applied on an unused microneedle patch.
As expected, the negative control absorption at 260nm is close to zero, no DNA is present in the microneedle patch.
In contrast, the positive control has the typical DNA Nanodrop readout.
The DNA extracted by microneedle patch shows significant absorption at A260. Its line higher than the negative control
but lower than the positive control. This means that some DNA was extracted but that it is not pure,
which is normal since, as mentioned previously, the patch extracts DNA and other molecules on the leaf.