Biomedical Engineering Reference
In-Depth Information
Magnetic particles can be efficiently used for the detection and determination of
target analytes in clinical biochemistry. Many devices have been developed such as
electrochemical immunoassay systems for the simultaneous measurements of several
proteins, flow injection analysis (FIA) employing enzymes immobilized on mag-
netic particles, magnetic separation immunoassay for digoxin with flow injection
fluorescence detection, sequential injection analysis with a chemiluminescence
detector for the determination of vitellogenin or immunoassay for sequential injection
analysis (SIA) (Aguilar-Arteaga et al.
2010
). Efficient preconcentration of target
analytes from large volumes of water or biological samples can be achieved using
Magnetic solid phase extraction (Šafaříková and Šafařík
1999
).
4.2
In Vivo Application of Magnetic Particles
Magnetic drug targeting employs magnetic biocompatible nanoparticles containing
a drug which could be injected intravenously, transported to a site of action (e.g.,
cancerous tumor or arterial blockage) and be retained at the site by application of a
magnetic field gradient. This form of drug delivery is advantageous in that a spe-
cific site in the body can be targeted by the magnetic field gradient, the doses
required for systemic drug delivery are reduced, localized drug levels can be
increased significantly with reduced potential toxic side effects at non-targeted
tissues, and a prolonged release of high localized drug concentrations at a required
site can be obtained (Vatta et al.
2006
).
Magnetic fluid hyperthermia, based on the fact that subdomain biocompatible
magnetic particles produce heat through various kinds of energy losses during
application of external AC magnetic field, is a promising approach to cancer therapy
due to the heating of the target tissue to the temperatures between 42°C and 46°C
that generally reduces the viability of cancer cells and increases their sensitivity to
chemotherapy and radiation. Unlike chemotherapy and radiotherapy, hyperthermia
itself has fewer side effects. Different types of magnetic biocompatible nanocom-
posites such as dextran-stabilized magnetic fluid, other types of biocompatible
magnetic fluids, aminosilane-modified nanoparticles, cationic magnetoliposomes
or affinity magnetoliposomes have been used for hyperthermia treatment (Goya
et al.
2008
; Safarik and Safarikova
2009b
).
Superparamagnetic particles are used as magnetic resonance imaging (MRI)
contrast agent in diagnostics applications. Particulate magnetic contrast agents
include ultrasmall particles (USPIO - “Ultrasmall superparamagnetic iron oxides”;
diameter between 10 and 40 nm), small particles (SPIO - “Small superparamag-
netic iron oxides”; diameter between 60 and 150 nm), and oral (large) particles
(diameter between 300 nm and 3.5 mm). Commercially available iron oxides based
contrast agents are usually stabilized by dextran, carboxymethyl dextran, carboxy-
dextran or styrene divinylbenzene copolymer (Laurent et al.
2008
).
A crucial aspect of successful cell transplantation is tracking and monitoring the
grafted cells in the transplant recipient. To screen cells
in vivo
, superparamagnetic
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