Particle-based immunoassays

BMP-IA bacterial magnetic particle-based immunoassay FIIA flow-injection immunoassay PFIA polarization fluoroimmunoassay. b BDD12AC benzyldimethyldodecylammonium chloride DDAC didecyldimethylammonium chloride. 

Gascon, J., G. Durand, and D. Barcelo (1995b). Pilot survey for atrazine and total chlorotriazines in estuarine waters using magnetic particle-based immunoassay and gas chromatography-nitrogen phosphorous detection. Environ. Sci. Technol., 29 1551-1556. 

Lawruk, T.S., C.E. Lachman, S.W. Jourdan, et al. 1996. Quantitative determination of PCBs in soil and water by a magnetic particle-based immunoassay. Environ. Sci. Technol. 30 695-700. 

J.A. Itak, M.Y. Selisker, D.P. Herzog, J.R. Fleeker, E.R. Bogus, R.O. Mumma, Determination of Captan in Water, Peaches, and Apple Juice by a Magnetic Particle-based Immunoassay , I. AOAC Int, H, 86-91 (1994). 

FIGURE 14.4 (a) Particle-based electrochemical immunoassay protocol (i) introduction of antibody-... 

JA Itak, Y Selisker, DP Herzog. Development and evaluation of a magnetic particle based enzyme immunoassay for aldicarb, aldicarb sulfone and aldicarb sulfoxide. Chemosphere 24 11-21, 1992. 

Fig. 38.2. Particle-based electrochemical immunoassay protocol. (A) Introduction of antibody-modified magnetic beads to magnet/carbon paste electrochemical transducer surface (B) binding of the IgG antigen to the antibodies on the magnetic beads (C) capture of the gold nanoparticle labelled secondary antibodies (D) electrochemical stripping detection of AuNPs. Reprinted with permission from Ref. [72].

McNally et al. have applied supercritical fluid extraction chromatography to the determination of diuron and linuron in soil [442]. Schlaeppi et al. [443] have described an automated magnetic particle-based chemiluminescent immunoassay for the determination of trisulfuron in soil [462]. 

Hottenstein, C.S., F.M. Rubio, D.P. Herzog, J.R. Fleeker, and T.S. Lawruk (1996). Determination of trace atrazine levels in water by a sensitive magnetic particle-based enzyme immunoassay. J. Agric. Food Chem., 44 3576-3581. 

Of particular note has been the development and use of particle-based flow cytometric assays. With this technology, a flow cytometer is combined with microspheres that are used as the soHd support for conventional immunoassay, affinity assay, or DNA hybridization assay. The resultant system is very flexible and has led to the development of multiplexed assays that simultaneously measure many different analytes in a small sample volume. 

In addition to these electrokinetic phenomena, electrostatic interactions among the microparticles due to their induced dipole are also observable [23]. The electrostatic interaction force, Fdipoie = r Sm Q fcM E [44], can make the particles form a structure like perl chain by attractive forces in the direction of an electric field, and a crystalline structure with a regular distances among the particles by repulsive forces in the plane perpendicular to the electric field. These electrostatic attractive and repulsive interactions can interfere with the precise control of microparticles using lab-on-a-display. On the other hand, we can utilize these phenomena for several applications such as a manufacture of self-assembled micropattem structures, a study about interactions between two cells, and a bead-based immunoassay. 

C.S. Hottenstein, S.W. Jourdan, M.C. Hayes, E.M. Rubio, D.P. Herzog, T.S. Lawruk, Determination of Pen-tachlorphenol in Water and Soil by a Magnetic Particle-based Enzyme Immunoassay , Environ. Sci. Technol, 29, 2754-2758 (1995). 

J.M.A. Schlaeppi, A. Kessler, W. Fory, Development of a Magnetic Particle-based Automated Chemiluminescent Immunoassay for Triasulfuron , I. Agric. Food Ghem., 42,1914-1919 (1994). 

Still using the same two-step procedure, monodisperse and thermoresponsive magnetic latex particles based on PNIPAM were prepared [157, 158], Anionic iron oxide nanoparticles were first adsorbed onto preformed cationic particles of various compositions [PS, poly(styrene-co-NIPAM) core-shell, or PNIPAM], The obtained heterocoagulates were then encapsulated with crosslinked PNIPAM through seeded precipitation polymaization (Fig. 24). The magnetic content varied from 6 to 23 wt%. These particles were successfiiUy used for the covalent immobilization of antibodies, and the resulting conjugates were tested as solid phases in immunoassays [159]. 

Core-and-shell composite particles based on inorganic cores with a polymer shell have also been investigated by several researchers, but do not seem to have reached industrial products. The reason for this is probably the high cost and possibly limited benefits of this type of latexes compared to existing products. A similar type of product is composite particles based on pre-emulsified polymers such as epoxies or polyesters (alkyds) with a subsequent addition of new monomers and polymerisation. This technique is partly connected to the process of miniemulsion polymerisation described in Section 1.2.2. A type of core-and-shell particles or at least multiphase particles may be obtained in this type of process. However, industrial applications of this type of products are not found on a large scale yet. Applications of polymer particles, mainly made by emulsion polymerisation, in the biomedical field was concentrated initially in the areas of blood flow determination and in vitro immunoassays. Microspheres have been employed for the determination of myocardial, cerebral and other blood flow and perfusion rates. Polymer particles and lattices, in particular, have been extensively used in immunoassays, starting in 1956, with the development... 

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