Microspinning: Local Surface Mixing via Rotation of Magnetic Microparticles for Efficient Small-Volume Bioassays

Abstract

The need for high-throughput screening has led to the miniaturization of the reaction volume of the chamber in bioassays. As the reactor gets smaller, surface tension dominates the gravitational or inertial force, and mixing efficiency decreases in small-scale reactions. Because passive mixing by simple diffusion in tens of microliter-scale volumes takes a long time, active mixing is needed. Here, we report an efficient micromixing method using magnetically rotating microparticles with patterned magnetization induced by magnetic nanoparticle chains. Because the microparticles have magnetization patterning due to fabrication with magnetic nanoparticle chains, the microparticles can rotate along the external rotating magnetic field, causing micromixing. We validated the reaction efficiency by comparing this micromixing method with other mixing methods such as simple diffusion and the use of a rocking shaker at various working volumes. This method has the potential to be widely utilized in suspension assay technology as an efficient mixing strategy.

Enhanced Microfluidic Sample Homogeneity and Improved Antibody-Based Assay Kinetics Due to Magnetic Mixing

“…Recently, the local effects of magnetic particle microspinning to protein–protein interactions were studied and the reaction efficiency was increased by 55% at 120 rpm. 28 Here, the MPS adds global phenomena that enhance fluid mixing, and the question is whether this effect is beneficial for accelerating biochemical sensing as well.…”

“…Our hypothesis is that good mixing will enhance the kinetics of the sensor–substrate and sensor–AB binding events, which will lead to faster sensor readout. Recently, the local effects of magnetic particle microspinning to protein–protein interactions were studied and the reaction efficiency was increased by 55% at 120 rpm . Here, the MPS adds global phenomena that enhance fluid mixing, and the question is whether this effect is beneficial for accelerating biochemical sensing as well.…”

Recent Advances on Nanocomposite Resists With Design Functionality for Lithographic Microfabrication

“…The authors used a digital micromirror device (DMD) as an efficient and versatile maskless lithography system. Following works of the same group showed the capabilities of such a NCPR in creating optical encoding particles and free-floating particles with multi-axis rotational magnetic control (Lee et al, 2010) and multiple magnetic microstructured actuators (Chung et al, 2011;Kim et al, 2011;Kim et al, 2013;Kim et al, 2020). Ge et al implemented structural coloring by coating the surface of superparamagnetic magnetite colloidal nanocrystal clusters with PLA or silica shells functionalized with alkoxysilanes for the further formation of reverse micelles.…”

The Fabrication of Amino Acid Incorporated Nanoflowers with Intrinsic Peroxidase-like Activity and Its Application for Efficiently Determining Glutathione with TMB Radical Cation as Indicator

“…Although these methods present the ideal sensitivity and selectivity for assaying the level of GSH in human cells or tissues, the application of a fluorometric assay suffers from the difficulties caused by the necessity for the derivatization procedures of the samples before measurement, the fact that the utilization of an electrochemical detector needs an operating electrochemical cell with a higher applied oxidation potential, resulting in its shortened life span, and high-performance liquid chromatography, capillary electrophoresis, mass spectrometry, magnetic resonance spectroscopy and surface-enhanced Raman spectroscopy require the use of the expensive, sophisticated and specialized apparatus as well as the requirement for experienced technicians, which severely confines the applications of these techniques in clinical chemistry [ 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 ]. Conversely, the colorimetric assay has received continuous attention as an attractive alternative strategy because it is a simple, convenient, sensitive and accurate route to accomplish the assessment.…”