Superparamagnetic beads

Superoxide dismutase copper containing, 7 776 Superoxide, photooxidation by, 9 386 Superoxide radicals, 17 772 Superoxides, 13 416-417 Superparamagnetic beads... 

Rgure 2.13. Superparamagnetic beads observed under an optical microscope (x40 objective) (a) under magnetic field (b) after field removal. (Reproduced from [37], with permission.)... 

As a flnal example, it should be pointed out that it is also possible to circumvent the need of immobilization of the biorecognition element in the microchannel system. Instead, it can be immobilized on superparamagnetic beads, silica beads, latex particles, etc. [79-81]. These beads are applied together with the sample into the microchannel system and can be collected on or near the transducer via magnetic or membrane separation. 

Superparamagnetic beads, with covalently linked streptavidin, are also commercially available (Dynal, Inc., Oslo, Norway, or Great Neck, NY Advanced Magnetics, Inc., Cambridge, MA Promega). Hornes and Korsnes (1990) found that hybridization is complete within a few minutes and that it is not necessary to have a large excess of capture probe (even at 1 1, the efficiency is close to 100%). A typical hybridization procedure, excluding detection step, takes... 

Ko PJ, Ishikawa R, Takamura T, Sohn H, Sandhu A (2012) Porous silicon based protocol for the rapid and real-time monitoring of biorecognition between human IgG and protein A using functionalized superparamagnetic beads. IEEE Trans Magn 48 2846... 

All superparamagnetic beads with radius a and magnetic susceptibility x subject to a homogeneous external magnetic field B develop a dipole moment with identical orientation and strength. 

In an external magnetic field of field strength B, a superparamagnetic bead with radius i p will have a magnetic moment of... 

Wang, D., He, J., Rosenzweig, N. and Rosenzweig, Z. (2004) Superparamagnetic Fe203 beads-CdSe/ZnS quantum dots core-shell nanocomposite particles for cell separation. Nano Lett., 4, 409—413. 

In another study, magnetic chitosan-alginate core-shell beads were developed for oral administration of small molecules to increase bioavailability level. The beads were found to be resistant in acidic media (stomach pH) and bioadhesive, presenting a superparamagnetic behavior and a very high entrapment efficiency [105]. 

Bead Based Microfluidic Platforms, Figure 4 Proposed detection principle. Microbead conjugated with superparamagnetic nanoparticles ( ). Unconjugated microbead (o) [4]... 

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