Magnetic nanoparticles for high-sensitivity detection on nucleic acids via superconducting-quantum-interference-device-based immunomagnetic reduction assay

In this work, we investigate the feasibility of detecting quantitatively DNA molecules utilizing the technology named after the immunomagnetic reduction (IMR) assay. Magnetic nanoparticles dispersed in a phosphate buffer saline solution were bio-functionalized with probing single-strand DNA. A superconducting quantum interference device (SQUID) ac magnetosusceptometer was employed to detect IMR signals related to the concentration of the target DNA. The results reveal that use of IMR assay had merits such as a high convenience level, e.g. wash-free processes and high sensitivity, down to pM, for DNA detection. ►The feasibility of assaying DNA molecules utilizing immunomagnetic reduction (IMR) is investigated. ►The sensitivity of the SQUID-based IMR was 0.03 fmol or 1.6 pM. ►It is also demostrated that SQUID-based IMR is able for the detection of single-nucleotidepolymorphism.