Magneto-Optical Biosensing Platform Based on Light Scattering from Self-Assembled Chains of Functionalized Rotating Magnetic Beads Sang Yoon Park Hiroshi Handa Adarsh Sandhu 10.1021/nl9030488.s001 https://acs.figshare.com/articles/journal_contribution/Magneto_Optical_Biosensing_Platform_Based_on_Light_Scattering_from_Self_Assembled_Chains_of_Functionalized_Rotating_Magnetic_Beads/2793136 We describe a simple protocol for the rapid, highly sensitive, and quantitative measurement of the concentration of biomolecules in a solution by monitoring light scattered by self-assembled chains of functionalized superparamagnetic beads (SBs) rotating in the solution. A rotating external field (<i>H</i><sub>ex</sub>) applied to an aqueous solution containing 250 nm diameter biotinylated SBs produced linear chains of SBs rotating in phase with Hex due to magnetically induced self-assembly. At constant Hex, the addition of avidin to the solution led to the formation of longer SB-chains than without the presence of avidin. The generation of longer SB-chains was revealed by increases in the amplitude of the oscillating optical transmittance signal of the magnetic colloid solution. Monitoring changes in the amplitude of the optical transmittance of the solution enabled quantitative determination of the concentration of avidin added to the solution with a sensitivity of 100 pM (6.7 ng/mL) and a dynamic range of at least 3 orders of magnitude. The rotating chains acted as biomolecule probes and micromagnetic mixers, enabling detection of biomolecular recognition in less than 30 s. This approach offers a rapid, highly sensitive, inexpensive, and homogeneous means for detecting biorecognition processes. 2010-02-10 00:00:00 Hex biomolecular recognition Functionalized Rotating Light Scattering monitoring light functionalized superparamagnetic beads Monitoring changes biorecognition processes colloid solution biomolecule probes transmittance signal 3 orders avidin 250 nm diameter biotinylated SBs micromagnetic mixers