This paper describes an aptamer-based optomagnetic biosensor for detection of a small molecule based on target binding-induced inhibition of magnetic nanoparticle (MNP) clustering. For the detection of a target small molecule, two mutually exclusive binding reactions (aptamer-target binding and aptamer-DNA linker hybridization) are designed. An aptamer specific to the target and a DNA linker complementary to a part of the aptamer sequence are immobilized onto separate MNPs. Hybridization of the DNA linker and the aptamer induces formation of MNP clusters. The target-to-aptamer binding on MNPs prior to the addition of linker-functionalized MNPs significantly hinders the hybridization reaction, thus reducing the degree of MNP clustering. The clustering state, which is thus related to the target concentration, is then quantitatively determined by an optomagnetic readout technique that provides the hydrodynamic size distribution of MNPs and their clusters. A commercial Blu-ray optical pickup unit is used for optical signal acquisition, which enables the establishment of a low-cost and miniaturized biosensing platform. Experimental results show that the degree of MNP clustering correlates well with the concentration of a target small molecule, adenosine triphosphate (ATP) in this work, in the range between 10. μM and 10. mM. This successful proof-of-concept indicates that our optomagnetic aptasensor can be further developed as a low-cost biosensing platform for detection of small molecule biomarkers in an out-of-lab setting.
Bibliographical noteFunding Information:
This work was financially supported by the ERC Advanced Grant no. 320535 -HERMES, the Danish Strategic Research Council project MUSE and EU FP7 Grant no. 604448 -NanoMag. J.Y. acknowledges the financial support from the Raymond and Beverly Sackler Program at the Interfaces of Biophysical and Medical Sciences at Columbia University . M.D. gratefully acknowledges financial support from the Ørsted Postdoctoral Grant. P.V. acknowledges the Basque Government (Program no. PI2012-47 ) and the Spanish Ministry of Economy and Competitiveness (Project no. MAT2012-36844 ). G.H.L. acknowledges support from Basic Science Research Program (NRF- 2014R1A1A1004632 ) through the National Research Foundation (NRF) funded by the Korean Government Ministry of Science, ICT and Future Planning and in part by the Yonsei University Future-Leading Research Initiative of 2014. T.S. acknowledges support from the ERC Starting Grant no. 209842-MATRIX .
All Science Journal Classification (ASJC) codes
- Biomedical Engineering