Magnetic microparticle

Technologies to purify cells from white cell concentrates are in the research stage. Principles used include antibodies covalently bound to a surface, antibody-coated microbeads in a column, magnetic microparticles that have been coated with antibodies, and hoUow fibers that have been coated with antibodies. 

The effects of cytoplasmic viscosity are widely unexplored. This may be attributed to the relatively difficult measurement methods available. In the cytoplasm, magnetic microparticles were predominantly used to obtain information on viscoelastic properties [125-127]. Clearly, the use of magnetic microparticles demands the use of very expensive equipment the observation of the particles is time-consuming, thus limiting temporal resolution, and the interaction between the particles and the cellular environment may also cause measurement artifacts. 

Whenever the commercially available particles do not match the operator s requirements, a variety of possibilities exist in order to modify the particles from company suppliers. Similarly to other doped beads the dyes [92] or quantum dots [107, 108] can be physically entrapped into magnetic beads by swelling or are covalently bound to the surface of the particles. If localization of the dye on the particle surface is desired or if the polarity of dye and/or matrix polymer does not allow the irreversible entrapment of the dye in the bulk polymer, a covalent attachment of the dye is preferable [109, 110]. Even the covalent binding of whole fluorescent nanoparticles to magnetic microparticles is possible, as shown by Kinosita and co-workers who investigated the rotation of molecular motors [111]. 

To overcome the nonspecific interactions between ssDNA-C and CCP, Fan et al. introduced a magnetic microparticle assisted assay [54], which allows DNA detection in human serum with 0.1 nM sensitivity. In addition, DNA intercalating dyes were introduced for DNA detection as shown in Scheme 5. These special dyes have much higher fluorescence quantum yields upon intercalation with dsDNA relative to those in the presence of ssDNA or in their free states. As a result, when complementary ssDNA strands (target and probe) are present, the intercalating dye... 

Kaminski, M.D. Nunez, L. Cesium extraction from a novel chemical decontamination process solvent using magnetic microparticles, Sep. Sci. Technol. 37 (2002) 3703-3714. 

Smith C, Kapsner K. A heterogeneous competitive assay for cortisol using magnetic microparticles and... 

Other microfluidic applications based on the manipulation of magnetic microparticles with external permanent magnets have been shown. One example is the ifee-flow magnetophoresis [108, 109], which can be utilized to sort magnetic microparticles by size. 

Figure 6. Merge, mix, split, and transport were the main manipulation steps used for on-chip droplet-based DNA purification. The system was able to extract genomic material from dilute raw cell samples by using the actuation of magnetic microparticles within the droplet using a matrix of coils [50],...

Additional examples of functionalized magnetic materials described in the literature for specific appHcations are summarized in this section. Magnetic microparticles with embedded silicotitanate have shown excellent adsorption ability for radioactive cesium isotope ( Cs) from HEDPA (l-hydroxyethane-l,l-diphosphonic acid), although dissolution of magnetite in acidic solutions in the regeneration step leads to a decrease in magnetic susceptibility (Kaminski and Nunez, 2002). 

Figure 12.12 Biobarcode assay for DNA detection. Magnetic microparticles (Mag) hybridize to specific targets. AuNPs functionalized with target-specific barcode strands are then added. After magnetic separation, the barcodes are released from the surface of the AuNPs by DTT. Subsequently the barcodes are detected using the scanometric method. (Reproduced with permission fi om C. S. Thaxton et al., Anal. Chem. 2005, 77, 8174-8178. Copyright 2005 American Chemical Society.) (See color insert.)...

Hamoudeh, M. and Fessi, H. (2006) Preparation, characterization and surface study of poly-epsilon caprolactone magnetic microparticles. /. Colloid Interface ScL, 300, 584-590. 

Magnetic beads (Glucose oxidase) Figure 7.13 Enzyme-immobilized magnetic microparticles. 

Further applications, such as isolation and purification of biomolecules, separation of biochemical products, or cell labeling and sorting, have been performed using magnetic microparticles. 

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