Paramagnetic-particle detection in lateral-flow assays Paramagnetic labeling offers an alternative method for analyte detection. Ronald T. LaBorde and Brendan O'Farrell The idea of using magnetic nanoparticles as analyte labels is not new. Researchers in the ferrofluid field have developed a variety of technologies and intellectual properties that use magnetic particles. Ranging from a few nanometers to several hundred nanometers in diameter, these colloids have been used in a wide range of applications. In the medical field, magnetic nanoparticles have been used in blood detoxification, biochemical separations, drug delivery, nucleic acid separation and detection, and as MRI contrast agents, and tamponades in retinal surgery. When employed to facilitate biochemical separations, colloidal paramagnetic-particle labels utilize the ability of antibodies to link selectively the analyte of interest to the magnetic nanoparticle. Whether it is a molecule, cell fragment, or complete cell, the analyte is then "labeled" with magnetic particles. Such particles must have the property of being superparamagnetic, meaning that they are only magnetic when placed in a very strong magnetic field. This is critical to their success as labels for separation or analyte detection. If the individual particles possessed a remnant magnetic field, each particle would act as a small dipole magnet, resulting in aggregates or chains as well as destabilization and precipitation of the colloid. To have practical utility, each paramagnetic particle (PMP) should also have surface properties that allow antibodies or recognition units to be linked to the particles. Such conjugated particles with the appropriate recognition units are then bathed with a fluid containing the analyte. After a relatively short incubation time due to the rapid diffusion of colloidal particles and the binding energies of antibodies, the analyte is magnetically labeled, and with the application of a magnetic field, the isolation or separation is performed. A simple extension of analyte labeling
Mass spectrometers separate ions by their mass-to-charge (m/z) ratios. They are used to identify compounds by the mass of one or more elements in the compound. They are also used to determine the isotopic composition of one or more elements in a compound.
Magnetic particle testing, sometimes called mag particle, MPI, or MT, is ideal for identifying surface or near-surface discontinuities in parts and assemblies whose materials have a certain degree of...