Ultra-sensitive measurements of magnetically labelled RCA products in a microfluidic channel using a high-Tc SQUID
Licentiate thesis, 2018
diameter of 100 nm.
Two different assay protocols are investigated for a magnetic nucleic acid biosensor. Padlock probes with suitable sequences are used as bioreceptors and circularize upon target recognition. The rolling circle amplification (RCA) provides the gain to the target molecule by copying the circularized padlock probe into a large concatemer. The specific binding of the MNPs to these large DNA coils changes their relaxation dynamics. These large DNA molecules can also digest into short monomers. The monomers can induce an agglutination if two MNP with matching sequence motifs to the two ends of the monomer are introduced. The agglutinated clusters would have large hydrodynamic size, thus, a different relaxation dynamics. The bioassay
has shown higher sensitivity using large DNA coils. Extrapolated sensitivity of the sensor to target analyte is estimated to be 66 fM of RCA coils. This is limit is equivalent to 1.0e5 target DNA molecules.
The method and instruments that are adopted and presented here are not limited to the Vibrio cholera bioanalyte and are generic and could in principle be used for other DNA or RNA viruses. The ultra-high magnetic sensitivity combined with the microfluidic sample handling is a critical step towards a magnetic bioassay for rapid detection of diseases at the point-of-care (POC). Future developments include implementation of all steps of the bioassay on a disposable lab-on-chip and eliminating the liquid nitrogen by operating the SQUID on a micro-cooler platform. These would make the magnetic bioassay promising for applications as a future nano-diagnostics unit.
rolling circle amplification
Chalmers, Microtechnology and Nanoscience (MC2), Quantum Device Physics
Volume-amplified magnetic bioassay integrated with microfluidic sample handling and high-Tc SQUID magnetic readout
APL Bioengineering,; Vol. 2(2018)
Areas of Advance
Nanoscience and Nanotechnology (2010-2017)
Life Science Engineering (2010-2018)
Biochemistry and Molecular Biology
Other Medical Engineering
Other Industrial Biotechnology
Technical report MC2 - Department of Microtechnology and Nanoscience, Chalmers University of Technology: 384
Chalmers University of Technology
Fasrummet, MC2, Kemivägen 9, Chalmers
Opponent: Professor Fredrik Höök, Department of Physics, Chalmers.