Independent thesis Advanced level (professional degree), 20 credits / 30 HE credits
Immunoassays are a very sensitive molecular diagnostics technique
that uses biochemical reactions to measure concentration of
biomolecules in a solution. ELISA is one of the most commonly used
type, based on fluorescence, in routine medicaldiagnostics. It is
time consuming and requires relatively large sample volumes.
Immunoassays based on magnetic detection are being developed. They
are faster, able to be made into point of care devices with
biological samples often lacking magnetic background. This project
focuses on developing an magnetic bioassay based on a high-Tc
SQUID with magnetic nanoparticles as tags. The expected
performance maybe two orders of magnitude better than ELISA
techniques, while not requiring several washing steps and being
able to perform in real time. Method of detection is based on
utilizing a padlock DNA probe-based recognition mechanism to
enhance the size ofviral flu RNA, binding the nanoparticles to the
padlocks and measuring the change in amplitude of the Brownian
relaxation peak of the unbound nanoparticles.
This thesis has been focused on developing a microfluidic sample
holder. Mircofluidics offer an advanced way to handle liquid
samples, with preparation, dilution, mixing and incubation on the
same chip, so called lab on a chip. During this thesis,
microfluidic channels made of PDMS were created. PDMS is a
suitable material because it is relatively cheap, easy to
manufacture and particles or padlocks do not bind to it.
Measurements of the real and imaginary parts of the AC
susceptibility as a function of concentration of both non
functionalized and functionalized magnetic nanoparticles
were performed in the microchannel with a volume of about 3 micro
liter. Extrapolating the results showed an equivalent iron content
sensitivity of 2*10^5 particles at 10 Hz. This result is about one
order of magnitude better than obtained in bulk samples of larger
2016. , 59 p.