<p>Prion
diseases are a group of fatal transmissible neurological conditions caused by
the change in conformation of the normal intrinsic cellular prion protein (PrP<sup>C</sup>)
in to the highly ordered insoluble amyloid state conformer (PrP<sup>SC</sup>). We present a rapid assay using Aptamers and Resistive Pulse
Sensing, RPS, to extract and quantify proteins from complex sample matrices, demonstrate
with the quantification of PrP<sup>c</sup>. We functionalise the surface
of superparamagnetic beads, SPBs, with a DNA aptamer. First SPB’s termed
P-Beads, are used to pre-concentrate the analyte from a large sample volume.
The PrP<sup>c</sup> protein is then eluted from the P-Beads before aptamer
modified sensing beads, S-Beads, are added. The velocity of the S-Beads
through the nanopore reveals the concentration of the PrP<sup>c</sup> protein. The
process is done in under an hour and allows the detection of picomol’s of
protein. The technique could be easily adopted to the mutated version of the
protein and integrated into clinical workflows for the screening of blood
donations and transfusions. </p>
The influence of sample matrix on the accuracy of nitrite N and O isotope ratio analyses with the azide method