Magnetic capture hybridization

Amagliani, G., Omiccioli, E., del Campo, A., Bruce, I. ]., Brandi, G., and Magnani, M. (2006). Development of a magnetic capture hybridization-PCR assay for Listeria monocytogenes direct detection in milk samples. /. Appl. Microbiol. 100, 375-383. 

Identification, magnetic capture hybridization, cyanobacteria, photosynthetic bacteria, hydrogen production, double-phase reactor, oxygen effect... 

S rDNA targeted identification of cyanobacteria using magnetic capture hybridization... 

Magnetic capture hybridization has attracted considerable attention owing to the ease with which specific target DNA may be isolated from a heterogenous sample. This simple method furthermore permits rapid concentration of target DNA from a bulk sample. It would therefore allow sensitive detection of target DNA from environmental samples, blood or other clinical samples. 

Takeyama H, Tsuzuki H, Chow S, Nakayama H, Matsunaga T. (2000). Discrimination between Atlantic and Pacific subspiecies of the northembluefin tuna (Thunnus thynnus) by magnetic capture hybridization using bacterial magnetic particles. Mar. Biotechnol. 2,309. 

Magnetic capture hybridization offers several advantages among them are speed and strong binding between biotin and streptavidin. However, the high cost of magnetic beads and low recovery of the RNA are often the major draw-... 

Fig. 12 Description of the magnetic capture hybridization method. Hybridization is first performed between RNA and biotin-labeled probes. The hybridized RNA is separated from the unhybridized RNA using streptavidin-coated magnetic beads...

Within the last decade applications of new cidture-independent molecular tools based on PCR analysis of soil-extracted nucleic acids have provided unique insights into the conqiosition, richness and structure of microbial communities (58-61). Quantitative PCR methods will be used to estimate the abundance in soils of genes that encode atrazine-degradation enzymes, and by quantifying mRNA, their expression. Magnetic capture hybridization (MCH) followed by nested PCR could predict die potential of a soil to mineralize atrazine (62). In diis study, atzA gene copy number was quantified and found to be correlated... 

Bach, H.-J. et al.. Magnetic capture-hybridization method for purification and probing of mRNA for neutral protease ol Bacillus cereus. Journal of Microbiological Methods, 1999 37(2) 187-192. 

Figure 8 Chemiluminescent (A and B) and bioluminescent (C) detections for immobilized hybridizations of PCR product. Dg, digoxigenin Bt, biotin Ad, avidin. Procedure A [30] Biotin moiety is incorporated into PCR products during the amplification reaction, using one 5 -biotinylated primer. The product is hybridized with a Dg-labeled probe and is immobilized on streptavidin-coated magnetic beads. This capture reaction is carried out for 30 min at 37°C. A permanent magnet is used to sediment the beads during washing to remove unbound DNA. By incubation with the washed beads for 45 min at 37°C, anti-Dg antibody conjugated to HRP enzyme is bound to the Dg-labeled probe, and luminol reaction is performed for CL detection. Procedure B [31] Wells of apolystyrene microtiter plate are activated with l-ethyl-3-(3-dimethylaminopropyl)-carbodiimide, and then coated with a labeled cDNA probe complementary to an internal region of the target DNA.

Figure 3.24 Schematic representation of the analytical protocol (A) Capture of the ALP-loaded CNT tags to streptavidin-modified magnetic beads by a sandwich DNA hybridization (a) or Ab-Ag-Ab interaction (b). (B) Enzymatic reaction. (C) Electrochemical detection of the product of the enzymatic reaction at the CNT-modified glassy carbon electrode MB, Magnetic beads P, DNA probe 1 T, DNA target P2, DNA probe 2 Abl, first antibody Ag, antigen Ab2, secondary...

Chan and co-workers (73) generated the novel mtinchnone-sydnone hybrids 127-128 by cyclodehydration of the sydnone glycine (125) and alanine (126), respectively. Trapping with DMAD gave 129 and 130. Maleic anhydride and dimethyl maleate failed to capture these mtinchnone-sydnone hybrids. Exposure of 125 to trifluoroacetic anhydride gave acylated mtinchnone 131 [by nuclear magnetic resonance (NMR)]. Workup afforded the hydrolysis product 132 (Scheme 10.24). 

The same immobilization strategy based on avidin/biotin linkage can be achieved on magnetic beads. After their efficient modification, the magnetic beads can be easily captured on an m-GEC transducer for the electrochemical determination of the hybridization event. 

ECL has also been applied to the analysis of polymerase chain reaction (PCR) products [53,55], PCR is first used to amplify the specific genes by use of two primers, one of which is biotinylated. The double-stranded DNA is then captured on streptavidin-coated magnetic beads and washed with an alkaline solution to denature and separate the strands. The particle-bound, single-strand DNA is used to capture products hybridized with Ru-labeled complementary... 

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